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1969 144s, B20B,"F" head (I think) twin SU HS6 carbs, distributor has vacuum advance.
From where does this distributor draw its vacuum?
I have the Voolvo "green book" factory manual, a Haynes, and a SU Carb manual.
None of these shows where on the intake manifold to connect the vac hose.
The green manual shows a distributor with a vac hose fold-out illustration "2-B B 20B engine (sith SU-carburettors) after page 2:58.
but there is no mention of a nipple in the listed components.
The intake manifold has large nipples for the brake boster and crankcase gas through the oil cap.
The air filter box has a large nipple for fresh air to the flame trap/oil separator, and a small nipple which is shown as the ventintg for the float bowls to the air cleaner.
No other nipples can I find on the carbs, the intake nor the air aleaaner.
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Hey Zee you got to many pokers in the fire LOL still trying to get the guys number to look at your escort ITB race car.
Eric
ps was running much better by end of weatherly weekend
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Eric!
Hey, man, where were you if not for Rose Valley?
(it sure was fun!) http://www.scxworldwide.com/ipb/index.php?autocom=gallery&req=si&img=310
Had a great weekend because the car was running right, after two years of tryin'
Was a bunch of little things, I guess. never one "Ah-ha"!
Hope to see you again at Polish Hill and Duryea
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Well, Eric, yeah, I have SEVEN "irons" to look after whenever I can carve out a little time for any one of them: 2 Toyota Avalons, 3 Volvos, 2 Fords and a Demco tow dolly which keeps following me around.
People give me cars like some friends give tomatoes or deer meat!
Haven't had time to do much on the Escort since Weatherly. Found a good FI harness in my spares. Pulled diagnostic codes which said the voltage from the VANE is low. don't know if this is a component failure, wiring problem, or just our radical adjustments.
Also, the EGO is always reading rich.
Not sure what to do about these things, but I did buy a new O2 sensor and I'll check all the wiring.
Just not a good sign when we needed to crank the VANE all the way open just to get the car to run 80% decently.
Spark plugs came home very sooty, as predicted.
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It is a vacuum retard unit, and it should be left disconnected. Many versions of the HS carbs had vacuum connections, some did not, and as George mentioned, all HIF do. They tend to be near the throttle plate edge to improve the vacuum signal, and to produce a timing change both at idle and slightly above in the "cruise" throttle position. If you can convert the distributor to an advance unit, fine, but if not, don't even think about hooking up the retard unit.
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Hi Zee--about - "don't even think about hooking up the retard unit" -- unless you experience a run-on condition when shutting the motor -- I think that was the original purpose of the retard at idle. Todays oxygenated (alcohol) diluted gasoline rarely causes that problem any more.
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Hey, Dave!
No run-on whatsoever. I guess I'll jst pt a vacuum cap over the nipple on the distributor and call it a day.
Thanks
Are ou coming to Carlisle for the Import show, or to Pocono over memorial day weekend?
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The purpose of retarding the ignition was to lower peak combustion temperatures and reduce NOx formation. It was commonly done in the early 70's on many engines. It reduces fuel mileage, and throttle response though. A very early, and lousy way, of controlling NOx.
If an engine runs on after shutting off, it's the result of combustion chamber deposits, rich mixture at idle, or too fast an idle speed, or some combination of these. It's better to fix that problem (s) than to use the vacuum retard.
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OK, thanks. I am dealing with richness, but not run-on. I have a faulty brake booster which is messing with the vacuum such that, when I step on the brakes, the engine revs. (and I hear a gush of air rushing at the booster)
The idle also wants to stay very high after a hard run and/or after the engine is nice and warmed up. I know to wait a bit with these HS6' for the idle to come down vs. others carb models, but my idle wants to stay high
I am going to try disconnect the booster vac hose at the intake manifold and cap that nipple. This should isolate the effect of the faulty booster and let me see hos the engine runs and idles (returns to normal)
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Some HS6 carbs and most HIF6s have an overrun springloaded valve in the throttle
butterfly, which can cause the high idle when there is enough vacuum to suck it open.
Joe Curto told me years ago to solder it shut if I didn't replace the butterfly plate.
Seems to have been very good advice. If you have them I recommend you do the same.
--
George Downs, Bartlesville, Heart of the USA!
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OK. maybe this explains why the idle was high (2000 rpm?) for about 5 minutes while I waited for some dumb-ass gasoline attendant to hold up the progress of six customers who chose to pay cash for their gas tonight.
While I waited my turn at the pump the idle just stayed high, then decided, on its own, to gradually slow down to where I had set it before taking a spirited run.
Seems that once this engine gets hot, I get this high idle -- at stop signs, etc.
Can't find any vacuum leaks. I disconnected the vac hose for the brake booster at the intake manifold and cappen that nipple. Best idle I ever had with this car.
Of course, I really need to plan ahead to stop the thing.
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Most had vacuum retard, rather than advance. If it is retard you can do as well
without it since it only retards at high vacuum (idle or hard deceleration).
The retard vacuum hose usually hooks to a nipple on the carb. HS6 carbs generally
do not have the vac retard nipple. Strombergs and HIF6 carbs do have it.
--
George Downs, Bartlesville, Heart of the USA!
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Maybe I am the "retard' because I don't know the difference between advance and retard.
anyhow, this isn't the original head nor carb set up. I believe from what I am reading in my "green" manual, this 69 would have come with HIF6 carbs, thus a vacuum nipple for the distributor.
Or Strombergs.
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Hook a hose to the nipple on the distributor and suck on it.
If the point plate moves in the same direction as the rotor turns,
it is retarding (firing later).
If it moves the opposite direction from the rotor, it is advancing (firing earlier).
The arrow on the side of the distributor shows the direction of rotation of the rotor.
--
George Downs, Bartlesville, Heart of the USA!
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What will that tell me, one way or the other?
Also, where do you set your timing? I thought I read you do 20 BTDC?
If I did that, I'd have high idle big time.
Unless I don't understand which scale to use on the crank pully.
The numbers face the engine. I am placing the timing at the 10 degree mark that is toward the driver's side, that is, to the left side of the scale.
Is this correct?
(actually, I gave it about 11-12 degrees)
Trouble is, I need to back off the idle screws almost until they no longer touch (engaged about 3/4 turn only)
So, if I am using the wrong scale, I can see hoe using the 10 degree mark to the right of the "0" will necessitate oipening up the throttle plates a lot more using the idles screws.
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If you have a low idle with the brake booster line plugged and it is high with
it connected (even when you are braking) you have a hole in the diaphragm of your
brake booster.
You should NOT have to retard your ignition to get a slow idle!!
Do you have valves in your throttle butterflies? If so, either get butterflies
without valves or solder the valves shut. They will make your idle too fast.
Yes, I do set my ignition at about 20° BTDC which will probably be about where it idles fastest.
--
George Downs, Bartlesville, Heart of the USA!
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Hiya, George,
Well the discussion at the VCOA tent Saturday during the Import Show in Carlisle, Pa had all of us confused for a while.
I was asking whether or not I was using the correct portion of the timing scale on the crank pully to begin with in my effort to time the car.
After much discussion, we joind a few other guys and foisted our thought upon them. After a while with them, we walked over to my '69 and confirmed I was using the correct side -- the side of the scale which has the 0-1-2-30 markings
During this discuccion, I asked about welding shut those by-pass valves onthe throttle plates. The one guy who was still advising (the others had fund their beers by now) said he thought it wouldn't be a good idea to do that, something else is probably wrong and causing the fast idle.
Momentarily, he gave me one of is business cards: it was Mike Dudek of iRoll motors and Foreign AutoTech. What a hoot! I had just receive dsome stuff I had ordered from him and also asked an email question about a booster repair kit seen on his web store.
He said I have the Ate brand booster, not the Girling, as I believed. and, no, there is no repair kit for the Ate.
He also advised I replace the dual-throllted intake manifold (with the secondary pre-heat throttles) with an aluminum intake having a striaght shot from SU carbs into the cylinders.
As the cars goes now, I have the booster vac port capped off. the car runs great once warmed up and gas milage seems good
But it idles slow and rough cold, doesn't want to start when hot, starts hard after sitting just a few minutes, and idles very high for about 5 minutes until is decides to return to a normal idle speed...for a couple minutes....
then is shuts itself off.
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Hello,
Your brake booster can be rebuilt.
I have done a half a dozen just for brickboarders alone.
Your car should have originally come with Stromberg carburators and not SU carburators and the vacuum port for the vacuum retard distributor was on the rear carburator on the mounting flange.
Soldering the decel valve on the butterflies should lower and stabilize your idle.
I also recommend removal of the secondary pre-heat flaps on the intake side and plugging the outer shaft holes.
--
Eric
Hi Performance Automotive Service (formerly OVO or Old Volvos Only)
Torrance, CA 90501
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I see that you still have some occurence of the high idle problem.
I don't want to argue with Mike but I have done as Joe Curto recommended, in
one case SOLDERED (NOT WELDED) the valves shut and in another case got butterflies
that did not have the valve in them and it solved the high idle problem in both
cases. You might be able to use the secondary butterflies in the cast arn manifold.
BTW If I were you, living where you do, I would keep the cast arn manifold and just remove the secondary butterflies and shafts, plugging the shaft holes.
Reason: At low speeds in very cold weather it helps driveability a lot just after
a cold start. My 69 164 is an example of this - it is ready to go within about
5 seconds of starting no matter how cold.
At high speeds in hot weather the mix is in the manifold such a short time it does
not get heated enough to affect performance measurably.
Also you don't have to use half washers or spotface the bolt holes in the exhaust
manifold to get it bolted on right.
--
George Downs, Bartlesville, Heart of the USA!
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I'm new to this board so hello :)
I've cleaned out the ZS carbs on my '71 164 and it's drawing in gas to the cylinders but I suspect the distributor is off because it wont start. The vacuum advance on my distributor has 2 nipples - one on top and another on the bottom. Currently I have the bottom nipple on the advance plugged and the top one connected to the bottom nipple of the front carb.
If I understand correctly the nipples on the top of the ZS carbs go to the exhaust gas canister thing and the bottom goes to the vacuum advance? Should I just plug all of them?
It's not currently starting (so I have no idle ;) but I rebuilt the carbs and gas is getting to the cylinder (puffs of smoke come out and it tries to fire randomly). I suspect the distributor/timing to be set all wrong and possibly old gas. Would my setting the vacuum wrong (if it is even) have anything to do with this?
Colten
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I had about a 10 year experience with Z-S carbs with lots of maintenance and was
able to keep them going but the problems got a LOT less when I changed to SUs.
I put on a pair of HS6s first and then put on some HIF6 carbs, which are more
like the Strombergs in the way they are fitted, linked, etc. The vacuum advance
goes to the tiny fitting on the manifold and the retard goes to the tiny one on
the carb - I think the one on the Stromberg is on the bottom near the mounting flange.
If I remember right I had a piece of tubing with a nail in it hooked to that fitting
as a vacuum plug so it wouldn't leak. You can get along fine without the retard
but if you have vacuum advance you should hook it up direct to the manifold.
See my previous posts in this string for how to tell which is which on the distributor.
Have you had the distributor or spark plug wires off the car since it last ran?
One of the big problems with Volvos is from timing them 360° off (on a 720°cycle).
If you are getting ignition near top dead center on #1 but it still won't start,
you might try switching ALL the plug wires straight across the distributor cap.
This would especially be indicated if it backfires but won't run when you are
trying to start it.
--
George Downs, Bartlesville, Heart of the USA!
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