I'm getting closer. New points, timing and dwell dead on, carbs synched and behaving, the engine tested combustion gas tight with the "blue fluid" radiator vapor suction tester, but I still need to pull the choke a little at higher rpms to get have any power at 50+mph.

I cannot find any more vacuum leaks. Brake booster is disconnected.

The throttle shafts seem tight enough, and spraying a little spray grease on them makes no difference even for a bit. The tiny little nipple (vac advance I think) on the rear carb is capped.

I've pulled the jets and double cleaned them. intake and exhaust valves all measure in spec and click nicely. Compression is 150 across.

I suppose the fuel pump could be weak, but they're so weak to begin with how could that make a difference?

I have an assortment of thermostats 180 to 195. It seems to warm up slowly, so that could be contributing.

The generator light glows dimly when the heater fan is on, indicates I may have a low voltage condition then, but it makes no diff in running when I switch it off.

I want to put in a Pertronix, but not as bad as I want it to run original before I do that.


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MPergiel, Walker, MI

Trying again - how many RPM does the engine run at when power is lost? Does it act the same in second gear?

If it does, I would suspect ignition, if it does not, I would suspect fuel because you use more fuel at a higher speed. but not at the same RPMs at a lower speed.

BTW - fuel, ignition and air - did you try the car with new or better yet, no air cleaners?


A point on fuel delivery.

I once drove a small straight truck to do transfers for a supermarket. My boss told me to drive no faster than 55. When i did try to drive 65, the truck would surge and vary between 65 and 55.

I asked my boss about this, he told me that the truck had a fuel restriction to keep me at 55.

The float bowl would run dry, the truck would slow, the float bowl would fill and the truck would speed up.

I ran this tale by a good mechanic and he told me that the behavior made sense, and he had seen it before.

After reading this whole thread I have one last thought not covered. Fuel starvation from partially blocked fuel line (tank to pump). I mention this because I had this and a little choke helped. Still was not right but masked the problem some. Old tanks and lines can block at higher liquid velocity, as particles stack up. Blockage is not felt in low fuel use situation.
Keep it simple.

I had the tank tanked and just put a fresh inline filter in front of the pump.

The first filter after tanking filled up with junk from the lines, which I had washed with acetone and lacquer thinner (used up what I had). Thius filter looks clean still.

The pump checked out, I think, but how many cranks should it take to start after sitting a few days? I just realized that now... it takes about 6-7 seconds of cranking to get it going after it sits 2-3 days.

In fact I'm going to top post just that...

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MPergiel, Walker, MI

One thing pretty well every one seems to agree on is carburation, but one question no one has asked, is there oil in the dampers. It causes the floats to act as an accelerator pump allowing more fuel at higher revs. Just a thought I wanted to add in case it had not been considered

Steve in Canada

U dont mention doing the valves so definitely do the clearance on valves..
If u are planning to upgrade ignition do so, I fiddled with my b18 alot until I put electronic ignition in. Good spark fixes many marginal problems. I had trouble finding reliable condensors when I still had points.

Could it be as simple as needles not seated all the way into the pistons? -- Dave

Try a new set of spark plugs 1st.
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69 142S Overdrive + 69 164S Manual

An obvious thing to try is to enrich the carbs one turn. When I bought my '64 544 with a replacement B20 engine, after driving it 25 miles home, the plugs were black.

The PO told me that he had just adjusted the carbs two turns - I reversed his adjustment and the car has run fine since. Actually, the engine has an occasional miss when it is fully warmed up, which to me indicates that it is a smidgen rich - since I do not drive the car a lot, and the plugs look great, I left it this way. I do not want it to run lean on the highway.

If it were your fuel pump, I do not understand how pulling the choke a bit would not make matters worse, asking for more fuel, making starvation worse.

I would suspect a weak coil (which, in my opinion is not likely) or perhaps a weak condenser - an easy and inexpensive item to substitute. Even those items do not lend themselves to the choke making matters better.

How are your air filters?

My uncle helped me buy a Mini in the 60s (I was 17) that did not run real well - my uncle negotiated a tune-up at the sellers expense. On the way home from a foreign car specialist, the car died on the highway and would not start.

I called my uncle who worked for a trucking company - he said - I'll send a REAL mechanic to look at it!

He pulled the air cleaner and the engine ran beautifully. He turned it 90 degrees and it worked fine.

The filter was made of horse hair, and the portion near the air horn was clogged with dirty oil!

I will check the condensor.. That could be it. I bought one but may not have installed it because it did not have a mounting tab.
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MPergiel, Walker, MI

Reading the post about the Mini with a blocked filter prompts me to ask what sort of filters you have fitted to your SU's. How does the car run on the road without them fitted? If the filters are wrong or they are fitted incorrectly, or have the gasket between the filter and the carb body wrongly fitted, the hole adjacent to the filter attachment holes could be covered up. This hole provides the vacuum for the carb pistons. If these or just one of them is blocked the pistons will hardly rise and so limit the revs available.

I'd also consider stuck advance/retard weights a possible culprit. They should rotate and snap back easily when you twist and release the rotor. The springs can also break or pop off which can also jam up the weights.

.... and the worst is a valve job or new cam.
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MPergiel, Walker, MI

Having to use the choke sure seems to point toward fuel mixture as being the cause... and the things that relate to the fuel mixture are the carbs. Not the coil nor the condensor. A weak coil or condensor could present symptoms similar to an incorrect fuel mix, but the choke shouldn't mask those symptoms. If the choke masks a symptom, it's hard to imagine the cause being outside the carbs.

That said: before you adjust or tune carbs, ensure that the ignition system is working properly.

Before you fiddle with the ignition, though, adjust the valves. Compression first, ignition second, fuel third. Address one thing at a time to avoid introducing multiple variables.

If the ignition system is proper and you have to use the choke, tune the carbs. If the carbs don't tune by following the steps in whichever manual you're using, you may well have the wrong needles.

Or a vacuum leak. If you're getting false air around the throttle shafts, that can make it run lean at speed, and no amount of tuning will make them work correctly.

Good luck!

Cameron
swedishrelics.com

Cameron;

I do agree with you that symptoms suggest to a carb issue, but I also have to point out that false air past worn throttle shafts has a lot more affect at idle than at high RPMs, where I'd say its pretty much out of the picture...it's a percentage of total air induced thing...when throttle is all but closed, there is a high vacuum and tiny gap past throttle shaft which is significant in comparison to allow false air in...but once throttle opening is off idle, 99% of induced air is coming in the normal and intended path...I can't reconcile symptoms for worn throttle shafts...

Cheers

Certainly true. I guess the first point I didn't make is that if the choke is needed, that my first inclination would be that the fuel mix isn't right; if we assume that the carbs have the right needles, then the two most likely possibilities are that they're not tuned properly, or they're not able to be tuned properly.

I guess it's possible that pulling the choke knob could mask the symptoms of a failing coil or condenser, but this seems unlikely.

The other point I didn't quite make is that I think it's important to ensure that the ignition system is working properly before attempting to tune the carbs.

By coincidence, I have an Amazon in the shop right now that came in because over the last year or so, it's begun running lean at higher rpms. It wasn't the carbs and it wasn't the ignition.

Best,

Cameron
Portland

Cameron;

We are in agreement and I don't mean to nickpick, but I just had to point out that false air past leaky throttle shafts is unlikely to cause stated symptoms, and that if pulling Choke at high RPM results in more even running, that certainly suggests it wants more fuel...so symptoms do point to a carb issue...could it be some sort of a linkage issue and pulling choke linkage somehow helps things???

...I'll be interested to read what the root cause turns out to be...

Cheers!

I don't imagine that this symptom can be solely the result of a linkage issue (though that may also exist). If it's the fuel mix, there aren't a lot of possibilities.

I'm curious to see the result too. I think it'll be that the carbs are good enough; and once the ignition is confirmed good, that we'll learn that there's excess blowby resulting in a pressurized crankcase; in turn resulting in unmetered air being forced into the intake manifold and causing a lean condition at cruise.

I'd be interested in what a leakdown test might have to say.

Best,

Cameron
Portlan

If it's blow-by diluting the mix I should be able to block the intake breather port and vent the crankcase to atmosphere.

I now suspect cam wear or burnt valves, thanks a bunch. Not really a problem. Compression tested well, although I hate to put new valves on old rings = old suck.

Neither would surprise me, although this car was last titled and inspected in NJ in 77, and it has a well used trailer hitch and the unsurprising clunks from the rear suspension blocks.

And I'll remove the new air cleaners. I removed the top and bottom plates and sandwiching in some generic filter (and support tubes), but all the ports are readily visible.

I changed the condensor no diff, and I added a 195 (!) thermostat that predictably made it run hotter, but not to the high mark.

Thanks for all the ideas.






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MPergiel, Walker, MI

If your compression tested good, it is not likely to be bad valves. You can check your cam for wear by removing the valve cover and putting a dial indicator on the lifters, pushrods, rockers etc. Very seldom to cams (or valves) wear evenly. With a little creativity and care you can even get an idea of the lift with a vernier caliper.

Will the engine rev up with no load or is it always running out of gas ?

Do your carbs have a drain for the float bowls ? If so, screw a barb fitting in there and attach a piece of clear tubing. It will give you a visual for your float level. Have you had the tops off the float bowls and looked to see that there is not a dead bug in there blocking the flow at high rpm ?

If you were running Amal Concentrics, I would say you need to step up the main jet...

Greg

It pulls well from 4.5k rpm with extra choke.

New wires, cap, rotor, points, condensor.

Could it be a "weak" coil? It's the original.

Maybe it's the manifold gasket. That's easy to replace and look for blow thru from exhaust ports.

I still go back to my faithful maxim: "99% of fuel problems are ignition."

Also, blocking the breather to intake made no diff.




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MPergiel, Walker, MI

Sitting in your driveway with no extra choke, will it rev to 4000 rpm and not fade away ? 5000 ?

I'm sure an ignition tune up won't hurt it but bad ignition makes for hard starting and misfires at high rpm or under load. Pulling the choke out usually does not help when you need a set of points.

Greg

It may have to wait until this weekend...

I like the instructional animations at the bottom of this page...

http://www.secondchancegarage.com/public/186.cfm
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MPergiel, Walker, MI

Michael;

Thanks for link...agreed...studying the various "scenarios" presented, and their respective Vac gauge action is interesting food for thought. The animated gifs are a nice presentation.

Cheers

Needles are known to be correct for the application?

Cameron
Portland

I took the dashpot cap off and removed the screw but the needle won't remove. I'm not inclined to grab it with pliers.

I removed the distirbutor and closely checked everything and it all looks good on all 4 lobes, with no slop.

I reamed and replaced the one bad throttle shaft bushing, front/front and both throttle shafts and plates.

It hasn't fixed the issue, may have put the throttle plates in wrong, because I only checked for light leak. They seemed to fit ok.

It's definitely behaving differently, so it may take just some tuning. I started back at centering the needle and 15 flats.

Here's my driveway reamer job.
https://www.youtube.com/watch?v=wr_vgZ5sA4M
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MPergiel, Walker, MI

Well the carb shown in the video is certainly wrecked! No mention was made of fitting new bushes before reaming to the correct size for the new shafts so not sure what is going on there. Accurate rebushing and reaming takes a bit off finesse and skill, especially getting the final line bore and reaming to match both sides. https://www.youtube.com/watch?v=LQykLNCcc0U
15 flats will be far to rich. Start at 12. Unlikely that both carbs will be in balance at the same number of flats and as an example one might be 11 and the other 13 but they aren't normally any further apart than that that.

Yes it's very easy to damage a needle when trying to remove it. A good looksee with a strong magnifier might show any signs of excessive wear. With the needle pointing straight up put a bit of cotton wool on the needle and push it down flush with the piston. Soak with PB blaster or similar, keep it wet. Do the same into the screw hole with the piston on its side. Add some patience. A bit of heat from a hot air gun can expand the aluminium a bit to enable you to pull the needle if you're lucky. It's pretty normal for them to be stuck but in your situation a bit of wear won't cause the major problem you are having. Good luck.

The standard SU kit comes with throttle shafts, plates, screws, split bushings and a bunch of gaskets and jets.

The reaming is to allow insertion of the bushings.

What else do you see "wrecked" about the carb?
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MPergiel, Walker, MI

My "wrecked" comment was re the amount of shaft slop you demonstrated in the video.
If the new shafts fit nicely and turn smoothly that's great. If one of the bushes goes in even slightly out of line that can cause problems.

Also, wouldn't excess blowby shut the PCV valve?
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MPergiel, Walker, MI

Hi there!

This sounds like a timing issue to me. Have you adjusted it at all?

Are you sure the distributor is advancing when it's supposed to?

The Pertronix kit is a wonderful upgrade. I'd do it and not look back. We have them available at IPD.

Give me a call if you want to talk about the car. We might be able to come up with something. I'm at 800-444-6473 x147.

Hope this helps!
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http://dylans544.blogspot.com

Posting here to be up top obvious.

Also in new thread elswhere on BrkBrd.

"It makes no sense to me, but new jets seem to have fixed it.

I tanked the bodies overnight just to make them pretty, and reassembled with new jets only and it runs up fine, at the basic settings with minimal tuning (balance flow at idle).

I should do a flow/drip test on the old jets.

I'm still going to try ZH needles which are a little richer. "

I also carefully reset the throttle plates. Loosened the screws, tapped body while jiggling plate until they were as fluid tight as possible. But that was not the issue.

I do NOT like that I threw parts at it.


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MPergiel, Walker, MI

Michael;

I don't like that you "threw parts at it" and fixed it without a good explanation either...

I have to believe that if in the course of replacing the jets, you "fixed" the issue, that either the jets had a flow problem (I have seen this, caused by a buildup of particles fine enough to make it through filter, but apparently course enough not to flow through jet supply tube and get ingested...instead they bound together to make a partial flow blockage) OR you inadvertently and without realizing it, changed something else which made symptom go away (if you changed jets, you certainly must have adjusted height position...did you just adjust them richer?).

Cheers