Volvo RWD 140-160 Forum
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SAVE Random B18 engine anomalies 140-160 1968
posted by drj434343 on Wed Jul 29 23:04 CST 2009
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last visit: Wed Nov 18 20:34 CST 2009[RELATED]I thought I'd conclude this saga with a nice story.
After tearing into my carbs, I discovered that not only were my jets different lengths, they were also too small. This created havoc trying to tune things. Additionally, the primary butterfly valves were incorrect, and I had play in my primary throttle shaft.
Eventually I decided to have Rhys rebuild the carbs. The transaction was painless, and he went above and beyond to do an outstanding job. Carbs came back as if they were brand new, and every detail was taken care of. I put them on the car, and it started right up.
After some tuning, the car is like brand new. More power, better economy, smooth acceleration. It really is a pleasure to have fixed all those issues in one effort.
I would highly recommend Rhys to anyone considering a carb rebuild.
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SAVE Random B18 engine anomalies 140-160 1968
posted by drj434343 on Thu Jul 2 15:14 CST 2009
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last visit: Wed Nov 18 20:34 CST 2009[RELATED]Alright, I've had a chance to completely remove the intake and exhaust manifold. I removed the secondary butterflies as recommended, threaded the shaft holes, and plugged them.
Everything coming back together, however, during installation, I accidently pulled out the fuel line going into the bottom of the jet on the rear carb. The fuel drained out of the float chamber, then stopped. I figured it would refill when I restarted.
Restart comes, car starts up after a few cranks with full choke. Let it warm up, and start messing around. Engine is extremely rough, like running on 2 cylinders (or one carb). I'm guessing I may have done something more serious. I sat there babying the throttle for 15 minutes, hoping normal fuel flow would resume. Adjusting the jets right now appears to do nothing. Without the choke half way out, the car won't run below 1500 RPM and some petal feathering. I'm currently at 12 flats down. With the choke half way out, it idles, but roughly.
The roughness with or without the choke extends to any RPM; the engine vibrates something fierce, and it feels like when I was running full choke and flooding it. However, leaning out mixture even more doesn't to anything to alleviate the "chug chug chug" I'm getting. Neither does richening it.
What could I have done to my float or something else during reassembly?
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SAVE Random B18 engine anomalies 140-160 1968
posted by RNANS on Fri Aug 7 22:56 CST 2009
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last visit: Sun Aug 9 20:01 CST 2009[RELATED]There is one possibility with regards to the problems you faced after yanking out the tube to the float chamber, the plastic tube within the springy outer sheath can get kinked and folded especially if it is hardened with age and heat exposure, and it becomes slit like at this point,
have a look at it, exact same thing happened to me once, ended up replacing the jet and the attached tube
Good luck
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SAVE Random B18 engine anomalies 140-160 1968
posted by drj434343 on Thu Jul 2 17:31 CST 2009
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last visit: Wed Nov 18 20:34 CST 2009[RELATED]I think I've been able to confirm a few things, but unsure of the cause.
First, I can get the car to idle now with the choke all the way in. It's really rough, though, struggles a lot. 12 flats down still on both jets.
Started reading about the lifting pins, and how they raise the piston, but I'm not sure how to see the piston raise, like some tuning instructions reference.
Anyway, I lift the rear carb pin all the way, and absolutely nothing happens to the engine. Roughly idles along with no change. When I lift the pin of the front carb all the way, it dies immediately. Instructions say that means it's too lean. Should I not lift that pin all the way?
Does the lack of any response on the rear carb lifting pin mean I'm not using it at all, or no fuel is flowing to it at all?
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SAVE Random B18 engine anomalies 140-160 1968
posted by Rhys on Fri Jul 3 11:34 CST 2009
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last visit: Sun Nov 1 01:44 CST 2009[RELATED]The rear carb is not flowing any fuel. When you re-inserted the jet pipe into the float chamber, you may have pinched the sealing ring. You'll have to remove the pipe, and install a new ring. They are located in this order, nut, small steel washer, seal ring. Move the assembly about 1/8 inch back from the end, and install, tightening the nut only firmly.
If you look into the rear carb after running the engine, the throttle plate will be dry, unlike the front one which will be wet. This will confirm that no fuel is moving through the jet.
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SAVE Random B18 engine anomalies 140-160 1968
posted by drj434343 on Fri Jul 3 12:56 CST 2009
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last visit: Wed Nov 18 20:34 CST 2009[RELATED]Thanks for those tips. I ran the car again, then peeked at the throttle plates. Both appeared to be wet. I pulled the fuel line out of the bottom of the rear carb jet (not the float bowl connect), and fuel flowed freely, so I surmised that unless there was a clog in the fuel line to jet connection, that wasn't the issue.
Then I noticed something peculiar. With the air filters off, peeking inside each carb throat, I noticed that even though both jets were tuned 12 flats down, the rear carb's jet (from inside the throat), appeared to be much higher than the front, almost totally leaned out.
To test it, instead of tuning each jet height by nut turns, I tuned them visually from the jet height in the throat. I left the front carb at 12 turns down, and to get the rear carb's jet to the same visual height as the front, I had to turn it down 29 turns!
As soon as I started the car with that configuration, it ran super smooth. It's clear I was running way to lean on the rear. And before all this stuff, when I tuned just by the nuts alone, I had to tune them both down about 24 turns, basically running the rear carb about right, and running the front carb super rich. That would explain my fuel economy.
So the million dollar question. Why, when I lower both jets 12 flats, do they look exactly the same height on the outside, but on the inside, its clear the rear one is much higher, and in fact needs more than twice the number of flat turns to get to the same honest height as the front one. Do I have different jets? Is something sticking?
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SAVE Random B18 engine anomalies 140-160 1968
posted by Rhys on Fri Jul 3 16:31 CST 2009
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last visit: Sun Nov 1 01:44 CST 2009[RELATED]It's possible that the jets are not SU original, or that the large nut that retains the jet bearing is loose and the entire assembly is turning.
Level the jets with the bridge and lower them equally to 10-12 flats. Check needle height in the pistons. Check float levels. If you are positioning the needles pull them out and check the letter code stamped on the shank. I've seen all kinds of incorrect needles installed in these carbs over the years.
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SAVE Random B18 engine anomalies 140-160 1968
posted by drj434343 on Sat Jul 4 12:42 CST 2009
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last visit: Wed Nov 18 20:34 CST 2009[RELATED]I've torn apart both carbs in search of an answer. This is after messing with tuning for hours, and not getting good or repeatable results. I've read different things about how to tune the mixture. Some say the results of lifting the pin to raise the piston shows the mixture of the other carb. Some say lifting that pin shows the mixture on that carb. Either way, I wasn't able to get understandable or repeatable RPM change results to make heads or tails of anything. So I ripped them apart. Here's what I found.
Front SU Carb
Rear SU Carb
As you can see, the rear carb's jet is longer than the front. Both needles appear to be the same. Would different length jets make these carbs pretty much untunable?
Another observation not shown is that after running the car a long time, then shutting it off and removing the piston and needle assembly, I had fuel pretty violently percolating out of the jet. I had to keep the needle in there to keep from loosing lots of fuel. It would do this for 15 minutes after shutting off the car. The rear jet didn't percolate at all. Am I boiling my fuel in the float chamber?
I can't find any identifying marks on the needles or the jets.
I checked everything else I could think of. The float chambers and floats themselves look in good condition. Neither float was leaking, and they both appear set at the same level.
At this point getting matched jets seems the logical step, but I'm not sure how to proceed. I'm trying to assess the condition of everything and figure out how deep a rebuild I want to go. Should I consider a complete rebuild at this point?
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SAVE mail address 140-160 1968
posted by Rhys on Sat Jul 4 15:34 CST 2009
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last visit: Sun Nov 1 01:44 CST 2009[RELATED]Email me from my website - I got your first mail, but there is no return address.
Rhys
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SAVE You've found it, and should be saying VOILA! right about now! 140-160 1968
posted by Ron Kwas on Sat Jul 4 14:48 CST 2009
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last visit: Sat Nov 21 19:32 CST 2009[RELATED]drj;
That 0.122" difference is certainly a big part of the problem...it looks like perhaps just one jet was replaced and not with an exact equal...I don't know off-hand which one is correct (probably the shorty if the protrusion I'm seeing in the rear carb is any indication), but maybe someone with a known factory carb can take some measurements...I believe the color bands on the flex pipe connecting bowl to jet may designate jet type, but Rhys should be able to confirm this...
...but given that the jet heights are different, I would check their orifice diameter, that is definately the critical parameter (knowing now that they are different, you could even deal with this...but their orifice governs the fuelrate and so it MUST be equal and 0.100...if you remove the set-screw which secures metering needle into dashpot, and remove the needles, you could use the metering needles as a gauge...needles are 0.0990 at their fattest not counting the mounting diameter.
...once removed from dashpot (use no tools to pull out!) Gently insert them into jet (avoid scratching!) and confirm that mere 0.001" of clearance. You can now also verify needle type...it's embossed into mounting surface.
The protrusion of jet of rear carb is keeping dashopt from falling all the way to bridge at idle...if you tried to adjust idle and mixture with jet in this position, I expect it would be damn near impossible!
What I would do: Get both jets to be flush with their brass glans, then reassemble and tune...a "rebuild" is not necessary now that you've found and will undoutably correct the root cause.
See also:
http://sw-em.com/su_carbs.htm
http://sw-em.com/SU%20Carb%20Service.htm
Cheers
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SAVE You've found it, and should be saying VOILA! right about now! 140-160 1968
posted by drj434343 on Tue Jul 7 16:57 CST 2009
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last visit: Wed Nov 18 20:34 CST 2009[RELATED]Ron, I went back and measured the orifice of both jets, and they were actually 0.09" ID's, but coupled with needles that were 0.990" OD. Combine that with the fact that the rear jet was 0.125" longer than the front. Weird set of equipment in this thing!
There were several other issues that needed addressing on these carbs, including some play in the throttle shafts, and the wrong style throttle plates. I priced out various rebuild kits because it seemed like a good idea to just return everything to stock while I've got it apart now. In the end, I actually decided to send them to Rhys for a rebuild. Taking into account the hardware costs, I felt like his rates were very reasonable, and I've heard he does excellent work. So they're in the mail now.
I do feel very satisfied with having found the real problem, and as strange as it sounds to now have someone else do the fix for me, it just seems worth it. While they're gone, I'll have a chance to convert to my alternator and replace my parking brake cable.
The list goes on!
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SAVE You've found it, and should be saying VOILA! right about now! 140-160 1968
posted by Kentucky on Tue Jul 7 18:50 CST 2009
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last visit: Sat Nov 21 08:56 CST 2009[RELATED]Given that you had worn throttle shafts in addition to the other issues, I think you made a good decision. With all that you found, I doubt that your dashpot / pistons were very well balanced, and I wouldn't be surprised if it had mismatched springs as well.
Let us know how it performs when you get them back.
Charley
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SAVE Random B18 engine anomalies 140-160 1968
posted by Rhys on Sat Jun 27 17:38 CST 2009
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last visit: Sun Nov 1 01:44 CST 2009[RELATED]Take the hose from the PCV off at the manifold, and plug the manifold fitting. Use duct tape or a short piece of hose and a bolt. Prevent any air entering the engine except through the carbs.
Then tune the carbs as to factory spec. It ain't fuel needles, it's you compensating for false air through the PCV.
Also check the manifold stud nuts for tight and be sure those aren't loose too.
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SAVE Random B18 engine anomalies 140-160 1968
posted by drj434343 on Sun Jun 28 22:27 CST 2009
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last visit: Wed Nov 18 20:34 CST 2009[RELATED]The thing that's confusing about those instructions are that even if I could tune the carbs to factory specs with the PCV hose disconnected, and let's say it really took 12 flats. The car has still made it clear that as soon as I reconnect the hose, it won't run at all at that mixture. What about tuning the carbs without the hose connected helps them perform better with the hose connected?
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posted by Rhys on Sun Jun 28 23:47 CST 2009
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last visit: Sun Nov 1 01:44 CST 2009[RELATED]What's happening is that the PCV valve is either malfunctioning or the wrong one for these engines. Most modern ones are for big V-8's and they don't work on these engines.
So disconnecting the hose and plugging the fitting is a diagnostic trick - get it?
It proves the problem is the PCV. The extra air coming through the hose does not pick up fuel in the carbs and that has a drastic leaning effect that you are trying to compensate for with wild tuning adjustments on the carbs, trying to get the mixture rich enough. That won't work.
The PCV needs fixing, and fiddles with the carbs and hopeful wishes won't repair it. Vent the crankcase to the air filter if you wish - most of the blow-by will find it's way into the engine to be burned. If low emissions is your game, buy a new Honda because there is NO WAY a B18 Volvo will EVER be a low emission engine.
Fix or disregard the PCV system and the engine will accept a normal carb tune and you can drive the thing.
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SAVE Random B18 engine anomalies 140-160 1968
posted by aaron74 on Sun Jun 28 22:57 CST 2009
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last visit: Thu Aug 6 12:44 CST 2009[RELATED]well, you've got two problems here 1) the mixture is wrong and 2) the crankcase ventilation system is malfunctioning. To my thinking the environmentally conscious solution to crankcase gas formation (i.e. PCV) is secondary as it is nice but not absolutely necessary to the safe functioning of the car. Your car will run perfectly fine if vented to atmosphere. But, when the mixture is badly out (as sounds to be the case) the functioning of the car is compromised. In this case, it sounds like the mixture is out at least partially because of the 'spare' air getting in through the PCV. So, plug it off at the manifold and the crankcase is vented to atmosphere AND the crankcase system is no longer a source of air leaning out your mixture. You can get back to the environmental niceties of the PCV later. In the meantime, the combustion byproducts resulting from poor carburetion far outweigh the off-gasing of hot engine oil, etc. You still have to fix both problems independently but for now, the PCV problem is complicating the carburetion problem.
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posted by drj434343 on Mon Jun 29 14:13 CST 2009
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last visit: Wed Nov 18 20:34 CST 2009[RELATED]I've had a chance to mess with blocking off the PCV system and trying a tune. It made absolutely zero difference. I totally blocked off the manifold connection, and allowed the PCV to vent to atmosphere. I repositioned the jets back to 12 flats. Same issue as before, the car simply starves out of fuel. It will only run with the choke fully out. Went all the way to 18 flats, car will only run with the choke half out. Finally went back o 24 flats. Car runs just as before, pretty well, no choke needed when warm.
I may or may not still have an issue with my PCV. However, it doesn't appear to have been affecting my mixture. Am I looking at figuring out how to get the needles out now?
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posted by aaron74 on Mon Jun 29 17:25 CST 2009
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last visit: Thu Aug 6 12:44 CST 2009[RELATED]Hiya,
Before messing with the internals of the carbs I would make sure there are no other air leaks. My brake booster leaks so it is permanently disconnected - you can check yours by disconnecting and plugging it off too (you also do not 'need' power brakes; I can lock up all 4 tires without the booster and the boots are a lot wider than stock). As Rhys has mentioned you will want to check your intake manifold over very well to make sure you do not have leaks at the manifold to head or manifold to carbs. What manifold do you have? If you have the same as me (at least the one on the car right now) there are secondary butterflies in the middle of the cast iron intake. If you have these, they are likely leaking - mine were. Remove. tap and plug with 1/8 pipe plug (the inside of the throttle shaft already has a plug).
Last but not least, we are at the carbs. Long before I would discuss needles, I would disconnect the throttle springs and wiggle the throttle shafts. Some people swear by using propane, butane, WD40, etc. but I have found that spraying extra fuel around is not always a good indicator of potential vacuum leaks. If the shaft has very much wiggle at all it is likely too much and you are getting 'spare' air around the throttle shafts; they are 41 year old carburetors after all. If this is the case you will need a throttle shaft rebuild - I recommend Rhys.
This does not rule out spare air from the brake booster an/or PCV system. In all likelihood you have multiple sources of spare air. Such is often the case when you are the umpteenth owner of a 40+ year old car. So, in summary, plug off all possible sources of spare air like the PCV, brake booster, and manifold butterflies (if you have them), check throttle shaft play in carbs (WITHOUT throttle shaft spring preload) and only then will it be pretty likely that the problem is not extra air leaning the mixture.
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posted by drj434343 on Mon Jun 29 21:37 CST 2009
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last visit: Wed Nov 18 20:34 CST 2009[RELATED]I've done some more investigation. This afternoon I removed the carbs and began poking around in the manifold.
After inspecting the the gaskets between the carbs and manifold, then the manifold and the head, I noted that they all looked brand new. This is probably due to the head gasket being replaced by the previous owner about 6 months ago. I'm guessing he decided to replace those gaskets when the head was off. At any rate, all the gaskets looked good to my eyes.
However, as you can see from the manifold picture, it appears I have those secondary butterflies, as you call them. I noticed that there appeared to be quite a bit of play in both their shafts. Could these be letting in enough air to be all of my problem?
While playing around with everything, it seemed like those secondary butterflies would actually open up when the throttle was wide open. Can I really just totally remove them and plug the hole?
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posted by aaron74 on Mon Jun 29 22:27 CST 2009
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last visit: Thu Aug 6 12:44 CST 2009[RELATED]Yep, remove and plug. George Downs has said that he was confident with sawed off bolts and goop but I drilled (only barely bigger than the existing hole, tapped and plugged mine) - the only problem with this is that you will likely be unable to do that to the back hole with it in the car, mind you the intake/exhaust gasket is only worth $10 here. You will likely notice instant improvement as long as the carb throttle shafts are not in the same shape.
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SAVE Random B18 engine anomalies 140-160 1968
posted by Rhys on Tue Jun 30 15:42 CST 2009
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last visit: Sun Nov 1 01:44 CST 2009[RELATED]If blanking the PCV doesn't make that much difference, then check float levels are correct - about 1/8 to 3/16 inch when inverted, and NOT compressing the spring in the needle if one is fitted. Also check that the needles are inserted so that the shoulder is flush with the bottom of the piston.
Worn shafts will cause poor running, but that as bad as you describe.
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SAVE Random B18 engine anomalies 140-160 1968
posted by drj434343 on Sun Jun 28 23:18 CST 2009
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last visit: Wed Nov 18 20:34 CST 2009[RELATED]I can accept your idea that excess PCV air going into the manifold can lean out the mixture, and cause also sorts of issues. That makes me worried however.
I can tune the car without the PCV hose connected, and I'll see what that does, but I'm left with a big issue. What in the world could be causing so much positive crankcase pressure? That sounds really bad.
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posted by aaron74 on Sun Jun 28 23:39 CST 2009
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last visit: Thu Aug 6 12:44 CST 2009[RELATED]There need not be excessive positive crankcase pressure. It just happens that there is vacuum at the manifold end. Possible reasons are that there is not excessive pressure and 1) faulty PCV 2) hoses old, hard (or soft) and leaky 3) flame trap plugged 4) wrong nipple feeding PCV (i.e. non-reduced fitting and hoses switched from brake booster and PCV). There could be crankcase pressure too - it is a 41 year old car but I would lean more toward the idea that something else is wrong and the vacuum will simply draw air if the rest of the ventilation system is not in good order. I think somebody else mentioned that Volvo's crankcase ventilation system changed over the years - you have to figure out what your year was supposed to be and then make sure it is routed correctly.
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posted by drj434343 on Mon Jun 29 00:03 CST 2009
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last visit: Wed Nov 18 20:34 CST 2009[RELATED]Whoa, your post is making me realize I'm a bit over my head here.
First, the routing. There is a red metal box coming out of the driver's side of the block, forward of the distributor. I take that to be a flame trap of sorts, maybe with some sort of valving (is that the PCV?). Looks original. A 1/2" ID rubber hose comes straight up from that to a T fitting. From there, one side of the T goes to the brake booster, and the other goes to the manifold. That's the extent of the system best I can tell.
Observations: I've unplugged the hose from the brake booster. It pulled a wicked vacuum.
Is the idea that the manifold should pull a vacuum under normal conditions? What is the flow of air past the PCV valve? Is there normally a slight crank case vacuum? The source of my question is trying to figure out where and how that PCV valve functions. Is it in that red box?
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SAVE Random B18 engine anomalies 140-160 1968
posted by
sdewolfe
on
Mon Jun 29 03:29 CST 2009
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last visit: Sat Nov 21 06:01 CST 2009[RELATED]
POSITIVE CRANKCASE VENTILATION
The B18A engine is provided with positive crankcase ventilation, see Fig. 14.
This arrangement prevents crankcase gases from being released into the atmosphere. They are instead sucked into the engine through the intake manifold and take part in the combustion process. The residue is blown out through the exhaust pipe together with the other combustion residues.
Between the engine crankcase and intake manifold there is a connection which consists of an oil trap (8) attached to the valve inspection cover on the right-hand side of the engine (viewed from the front), and two rubber hoses (5 and 7) between which there is a control valve (6). The rubber hose (5) is connected to a nipple (2) screwed centrally in the equalizing pipe of the intake manifold.
The partial vacuum which occurs when the engine is running causes the crankcase gases combined with the fresh air to flow from the crankcase to the intake manifold. The amount of flow is regulated by the control valve. Fresh air is supplied to the crankcase through the carburettor air filter via a nipple (1), rubber hose (3) and oil filler cap (4) to the rocker arm casing, which is connected to the crankcase through the push rod holes. The oil filler cap, which is sealed, has a built-in flame trap. This flame trap, in the same way as the control valve, which also functions as a check valve, prevents flame from any backfiring in the carburettor or intake manifold from reaching the crankcase.
As the fresh air supply passes through the carburettor air cleaners, impurities are prevented from getting into the engine. Where there is a medium or high degree of partial vacuum in the crankcase (intake manifold), which happens during idling and when operating under a light load, the system functions as described above. When the partial vacuum in the crankcase is less than that in the air cleaner, which occurs at full load and/or with large flow quantities, no fresh air is supplied. Instead, the flow in the connection between the rocker arm casing and the air cleaner reverses and the crankcase gases go both ways, partly through the control valve and partly through the air cleaner and carburettor to the intake manifold. In this way, the crankcase ventilation system can deal with relatively large quantities of crankcase gases without any escaping into the atmosphere.
Volvo Green Book 02a Engine B18A, pg. 2-15
--
Mr. Shannon DeWolfe -- I've taken to using mister because my name misleads folks on the WWW. I am a 53 year old fat man. ;-)
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posted by derek uk on Mon Jun 29 03:52 CST 2009
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last visit: Sat Nov 21 16:37 CST 2009[RELATED]The PCV valve is fitted inline in the pipe at about figure 6. You can see it there. It goes block ear-very short hose-PCV valve-hose over the valve cover. From the OP's mails I can't be sure if there is one fitted. Only the correct one will do. A main dealer will supply or someone else here will pipe up.
Doing a search here for "B18 PCV" gives a reply from 2003 by Phil Singher
Fram FV112
AC CV768C
Standard V112
Niehoff PV280
...or any part number that cross-references to any of those.
I don't know if all of those are still current.
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SAVE Random B18 engine anomalies 140-160 1968
posted by derek uk on Sat Jun 27 05:05 CST 2009
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last visit: Sat Nov 21 16:37 CST 2009[RELATED]There are lots of threads here on the BB for SU tuning problems, many in the 120 section. Currently one is near the top of the list. Comments by Phil Singer, who is also in Portland Oregon I think, posted this
Questions re: SU tuning
You might be able to tempt him to look at your carbs, I'm only saying might to cover myself.
With reasonable summer temps you should be able to push the choke back in a third to a half, virtually as soon as the engine starts. By the time the water temp gauge starts to come off it's stop, the engine should run along steadily with no choke but it may need a tweak out again if your first junction is only a few hundred yards down the road. By the time the needle is in the middle of the green all should be running easy. Any time it's chugging and putting out black smoke it's way over rich. As the SU doesn't have a pump jet for a bit of extra juice it has to balance itself out until the motor is warm. Pumpng the throttle when trying to start doesn't do any good but putting the pedal to the floor will clear out any excess fuel for a while. You give it a bit of help by nudging in the choke in the first few minutes of running, takes a bit longer in the winter. When the engine is up to temp you should be able to reach in and turn the key for it to start and settle to normal idle without touching anything, choke or throttle. That normally proves that all of your settings are just about right.
Currently yours does sound as if it's running very rich. If both the jet settings are about 12 flats down, maybe +1/-2, it sounds as if the one or maybe both of the jets are sticking down to some degree. With the filters off you can check how they work through the range of the choke control, they should both move the same, but when you next go out and it has the problem, just stop the car, leave the engine running and physically see if you can push the jets up. DON'T burn your self on the exhaust manifold!
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SAVE Random B18 engine anomalies 140-160 1968
posted by drj434343 on Sat Jun 27 12:13 CST 2009
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last visit: Wed Nov 18 20:34 CST 2009[RELATED]QUOTE: "Currently yours does sound as if it's running very rich. If both the jet settings are about 12 flats down, maybe +1/-2, it sounds as if the one or maybe both of the jets are sticking down to some degree."
I've had a chance to mess with the car this morning. First off, I was operating the choke fully out way too long, essentially flooding the engine like others have mentioned. I started cold with it fully out this morning, and after about 5 seconds, was able to push it in 1/2 to 2/3rd's the way back in, and everything was fine. No black smoke or struggling.
However, I went back and started from scratch on the mixture. I tightened both jets all the way up and counted 12 flats down on each, like the above quote recommends. The car wouldn't even run under 2500 RPM, it would totally die. I kept lowering the jets. At 14-16 flats, the car would run, but would die anywhere below 2000-1500 RPM. Finally, at 18 flats each, the car will run pretty well at 1000 RPM.
I don't know if this means the car will only run rich and I have other problems, or if I've tuned it correctly now, and my jet nuts just needed more turns than others. Thoughts?
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SAVE Random B18 engine anomalies 140-160 1968
posted by drj434343 on Sat Jun 27 15:23 CST 2009
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last visit: Wed Nov 18 20:34 CST 2009[RELATED]UPDATE: At 18 flats, the car would idle at 1000 RPM, but whenever I attempted to accelerate away, the engine would really struggle for power, like it was totally bogged down, if I was accelerating from any RPM less than 2000. It wasn't until I got to 24 flats down that I can get smooth and clean acceleration from pretty much idle. I don't see any smoke at this point, but the jets are back to about where I had them before.
Ideas?
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SAVE Random B18 engine anomalies 140-160 1968
posted by derek uk on Sat Jun 27 17:20 CST 2009
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last visit: Sat Nov 21 16:37 CST 2009[RELATED]As said, maybe wrong needles. Remove one at a time and tell us what they are along with the type of air filters you're using. Needles may have been fitted with the mounting end not flush with the piston. Not unknown to have someone try and tweak the mix a bit by changing their positions. If your needles are the sprung loaded ones, check to see if they are lined up correctly, see manual.
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SAVE Random B18 engine anomalies 140-160 1968
posted by Pebee on Sat Jun 27 15:20 CST 2009
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last visit: Mon Nov 9 06:57 CST 2009[RELATED]Having had the identical problem, I'm more sure than ever that the needles are wrong
Pete.
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SAVE Random B18 engine anomalies 140-160 1968
posted by drj434343 on Sat Jun 27 15:24 CST 2009
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last visit: Wed Nov 18 20:34 CST 2009[RELATED]As in, wrong size or type? Or wrong adjustment? I don't know very much about messing with the needles at all on these SU's.
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SAVE Random B18 engine anomalies 140-160 1968
posted by Pebee on Sat Jun 27 20:42 CST 2009
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last visit: Mon Nov 9 06:57 CST 2009[RELATED]I mean the wrong type needle. For instance, the Clymer book shows type KA for the B18D engine. In my case the ones fitted were meant for a B20 High Comp. engine. There is no adjustment on the needles. Fit them with the shoulder flush with the suction chamber. I don't know the specs for your car, but Joe Curto is a great source for parts and advice.
Pete.
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SAVE Random B18 engine anomalies 140-160 1968
posted by Pebee on Fri Jun 26 19:55 CST 2009
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last visit: Mon Nov 9 06:57 CST 2009[RELATED]If you find your problems were due to flooding or choke adjustment, you will need to put in new plugs, before you start tuning it up.
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SAVE Random B18 engine anomalies 140-160 1968
posted by alschnertz on Fri Jun 26 18:36 CST 2009
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last visit: Sat Nov 21 22:00 CST 2009[RELATED]Reading your post, you don't say if you are pushing in the choke after it starts. You should begin pushing the choke in slowly after the car starts.
Push it in about 2/3 of the way and leave it there until it's warmed up which is usually about 4-5 minutes tops.
If it is acting as you say after it is warmed up and the choke is in, then it is running too rich. Check to make sure the jets are moving all the way up when the choke is pushed in. It's not unusual for them to stick in the down position thus making the car run very rich.
--
Lubricate your distributer!
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SAVE Random B18 engine anomalies 140-160 1968
posted by drj434343 on Sat Jun 27 00:59 CST 2009
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last visit: Wed Nov 18 20:34 CST 2009[RELATED]I may be leaving the choke out a little too long, or at least too far for too long. I'll try your order on the next cold start. The largest smoking incidents occur when I try to take off and the choke is totally out. It sounds like I should never drive off with it more than 1/3 out?
I'm really confused about the mixture. I've been fine tuning the jets on and off for weeks. I feel like I've got them adjusted almost all the way up, and I was sure that meant I was on the lean side. Given that the choke cables pull them down, rich was down, lean was up. If your suspicions are true, I don't know how much more I can adjust them up. I've gotten them up so high in the past by tightening the nuts that the engine has started to die.
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SAVE Random B18 engine anomalies 140-160 1968
posted by
sdewolfe
on
Sat Jun 27 04:48 CST 2009
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last visit: Sat Nov 21 06:01 CST 2009[RELATED]The next time you start the car from cold, after you have pushed the choke back "home", open the hood and check the position of the jets by pushing up on them. If the choke mechanism is sticking the jets will be down from their fully up position. You may find one jet up and one down.
BTW, down is rich, you've got it.
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Mr. Shannon DeWolfe -- I've taken to using mister because my name misleads folks on the WWW. I am a 53 year old fat man. ;-)
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SAVE Random B18 engine anomalies 140-160 1968
posted by alschnertz on Sat Jun 27 04:45 CST 2009
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last visit: Sat Nov 21 22:00 CST 2009[RELATED]There shouldn't be any need to have the choke fully out when driving. Only starting.
When fully out, it should rev up to around 2700 - 3000 rpm.
Out a third, should be around 1600 or so.
You can't really adjust the choke mixture. It is merely a function of the jets dropping down. So if you have your idle mixture set properly, there is no mixture adjustment to the choke that can be done. You can adjust the fast idle speed though.
Be sure you check for sticking jets. I have had that issue often. The jets don't always release back up after pushing in the choke. That will lead to poor running and black smoke.
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SAVE Random B18 engine anomalies 140-160 1968
posted by Pebee on Sat Jun 27 10:17 CST 2009
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last visit: Mon Nov 9 06:57 CST 2009[RELATED]Check the specs and make sure that you have the correct needles in the carbs!
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SAVE Random B18 engine anomalies 140-160 1968
posted by walrus3 on Fri Jun 26 18:10 CST 2009
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last visit: Sat Nov 21 18:07 CST 2009[RELATED]It's flooding.
Could be leaky float valves, float level too high, fuel pressure too high (off-brand fuel pump) etc.
The black smoke = mixture WAY too rich. Behavior confirms it. So does gas mileage.
Fuel pressure should be 3 psi or less. Set float level per the manual.
--
George Downs, Bartlesville, Heart of the USA!
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