Since I don't know where to start looking for what's wrong I'll give it its own post.

Basically added a new carb and converted to EI a few months ago and have never got the set up working properly. Yesterday I tried setting the valve lash hot and it didn't need it, all tappets were at the correct position.

Car idles normally and runs and drives ok, but feels sluggish (performance not as good as the last carb, which was an old remanufactured unit that was leaking everywhere). Limited acceleration even at WOT.

At hot idle (out of gear), I only get 15" hg vacuum at the #6 runner (620rpm idle). When I pull the vacuum gauge from the runner, idle jumps to around 900rpm. The last carb I had, pulling the vac gauge would kill the engine.

Static timing is at 8 degrees, advancing through to 12 gives a little more power but seems to run a bit rougher too.

Compression is between 145 and 155 in all cylinders, and it has the stock cam.

Uses Mopar EI with an old car parts distributor, and an electronic choke hooked up to a '63ish rebuilt NOS Carter BBS, which I have had apart many times attempting to find the problem, but all seems well.

Kind of out of ideas a bit now, I'm going to try and verify TDC and look for vacuum leaks today, but I don't believe these are at fault.

Any and all help you could offer would be greatly appreciated.

All the best,
60Ply

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1960 Plymouth Belvedere 4 door sedan
Stock 60 225
Push button 3 speed Torqueflite
Right Hooker

The vacuum tap at #6 is not the best place to read you manifold vacuum, try hooking up near the carburetor.

Is the choke you installed functioning as it should? Arrest me if I am mistaken here, but getting higher revs when adding air to an engine, means something is restricting the intake, and ususally the carb is giving too fat mixture, the engine not being able to burn it off without the extra air. As you said, the normal behaviour is that the engine stalls. You should probably see in on the exhaust, does it make a black stripe/spot on the ground after the tailpipe?

Secondly, are you sure than the timing marks on the balancer actually show TDC? The outer ring that have the marks on the balancer, is set in a rubber compound against the inner ring, and they have a bad reputation for slipping with age.

Thirdly, what governor and vauum unit do you have in the electronic distributor you installed; 12° static advance may be too high, if the distributor is an early model. They typically could give up to around 30° added mechanical advance - depending upon the advance weight springs, and you should try to limit the initial+mech advance to 30-34° maximum.

Check if the distributor vaccum pod is connected to ported vacuum and not manifold vacuum, there should be no vacuum in the line when the engine is idling (not entirly correct, you may actually get a very low vacuum reading, but not enough to affect the vacuum pod).

Olaf

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Aspenized

Hi Olafla, thanks for the response.

I'm afraid the #6 intake runner and the PCV are the only places I can tap vacuum on my car (without a drill). I have the early internal piston choke pull off on my carb, so have very little to work with on that front. The gauge is attached to a long hose which seem to iron out the 'pulses' a whole lot.

Does the PCV see full manifold vacuum? If I could get hold of a hose 'T' I could use that.

I tend to agree about the mixture being too rich - I'd expect opening a huge vacuum leak to allow the engine to die from too lean a mixture.

I did have a very rich condition associated with the choke a few weeks ago. I thought I had corrected that (choke rod was fouling on air cleaner). The choke is no longer fouling and I can get full travel, and no black soot on the ground.

Even so, the current problems I am getting are with the engine hot and the choke wide open (this isn't to say that cold operation is perfect at the moment, I just think that if it happens hot with the choke wide open also then the choke can be eliminated for this condition - is this a reasonable assumption?).

What is strange is that I can adjust the idle mixture using the normal procedure - I can slow the engine down by both enrichening it and leaning it out. This to me implies that the mixture is in a sensible ball park at idle, which is kind of at odds with what happens when the vacuum port is open. Any other reason pulling the tube from the runner would net an increase?

In addition, plugs look ok, maybe a little rich but nothing stupid, but as I said in the other thread, there aren't a whole lot of miles on this carb (how long does it take a plug to 'react' to the mixture condition?). I did have black smoke/soot when the choke was fouling, but haven't really noticed any since.




Regarding TDC: this is the next thing to check, when I can find my piston stop, my gut feeling is that it's ok though (the marks are home made, and the engine was rebuilt about 15 years and about 20,000/30,000 miles ago).

Even so, adjustment either way doesn't alter vacuum (advancing the dizzy does give an increase in RPM though, I've run out of travel at 12).

I understand that the ideal static timing for a dizzy can be found by setting it at the advance where manifold vacuum is highest for a given idle speed? The only reason this isn't normally done is that the mechanical/vacuum advances may then be hurt at higher RPMs. If this is true, altering the base timing should yield a change in vacuum. Is there any truth in this?

EI dizzy is from old car parts northwest, and circa '65ish I believe (Dan may be able to help there). I had timing at 8 degrees before - not a whole lot of difference between 8 and 12. I don't see much change in vacuum either, maybe slightly higher at 12 than 8. And I certainly don't detect any pinging noises, just slightly rougher running.

When timing the engine, the light does not seem to jump around, I get maybe a degree max difference, and that's only during the odd 'stumble', and only lasts one fire.

Dan suggested to check the vacuum advance. I can advance it by sucking on the hose (blocking the carb port with my finger) and seems to hold when I close it off. In addition, I'm getting low vacuum at idle, when ported vacuum is 0, so by my reckoning this can't be a problem. Is that right?

Anyhow, I can clear up whether the timing is accurate or not once I find my piston stop.



One thing I haven't done is check for vacuum leaks, but the deliberate vacuum leak seems to have the opposite effect from normal, so I don't suspect any. Does this make sense?

Forgive the long post - I'm trying to put as much information down as I can so everyone has something to go on.

Thanks for the response Olafla, look forward to sorting this out.

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1960 Plymouth Belvedere 4 door sedan
Stock 60 225
Push button 3 speed Torqueflite
Right Hooker

Haven't found my piston stop, but discovered that my base advance (according to my crank timing mark) can be as much as 30 degrees and still idle, idle speed actually increases slightly with this much base advance. Towards zero degrees the engine starts to slow excessively.

This just seems odd, I wouldn't have thought you could get that range of base timing and the engine still run.

_________________
1960 Plymouth Belvedere 4 door sedan
Stock 60 225
Push button 3 speed Torqueflite
Right Hooker

Another thing to check would be that you have timed the motor to fire at TDC on the correct stroke.

Years ago I purchased a 1976 Plymouth Volare out of a junkyard and got it running for some friends of mine. It rans and drove great, until my friends decided to give it a tuneup. One of the things they did was install a new cap and rotor. Somehow they managed to get the spark plug wires onto the new cap in the correct firing order, but install the cap on the distributor 180 degree off. As a result, the engine was firing on the exhaust stroke.

My friends ran the car like this for a week before they called me up and wanted to know if I could fix it. The car had died on the highway when they were driving it, but they said before it died it ran OK but lacked power. I towed the car back to my place and discovered that they had run the car out of gas. I added gas and it started right up. I started trying to diagnose the lack of power and spotted the distributor cap right away. I flipped the cap back the right way around and the car ran beautifully. I ended up buying the car off my friends for a couple hundred bucks.

My point is that it is possible for a slant six to run, albeit poorly, with the timing 180 degrees off. When you check that the engine is at TDC when the rotor is pointed at the #1 plug tower, make sure it is at TDC on the compression stroke. The best way to do this is to remove the valve cover and rotate the motor by hand, watching the movement of the valves. Watch for the #1 intake valve to open and close. The next time the timing mark is at TDC on the timing tab after the intake valve closes is when the rotor should be pointing at the #1 plug tower on the cap.

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Casually looking for a Clifford hyperpak intake for cheap.

Hi Reed,

I think I had that problem when I first installed the distributor. I removed the valve cover and got it to the TDC mark. When both rockers were 'loose' then the valves must be closed.

Worth a go though. I'll find the correct TDC position tomorrow and do the timing from scratch with a known 0degree mark.

Thanks a lot,
60 Ply

_________________
1960 Plymouth Belvedere 4 door sedan
Stock 60 225
Push button 3 speed Torqueflite
Right Hooker

I doubt that a vacuum leak can cause your troubles. A correct ignition point should definitely give higher vacuum, all other settings being equally correct. Is this done without any vacuum line connected to the distributor?

Let me push some theory, stretched into the extremes: If the vacuum pod is incorrectly connected to manifold vacuum, letting the engine suck air through the connection on #6 may reduce the vacuum in the manifold, and therefore also lower the vacuum to the pod on the distributor, and speed up the engine because of less advance. The culprit is that you should see that immediately when revving the engine with a timing light connected, and usually also bring you into the ping zone right away.

I do presume that the sluggishness you experience now, has come gradually after the new parts came into use, and is not a direct before/after comparison, which would be an entirely different scenario. Then I'd start with finding the engine's sweet spots, and do a distributor recurve.

Since the only changes you have made, are the carburetor, choke and distributor, it is important to eliminate any other possible sources: How is the rest of your drive line, is the car behaving normal when just rolling in neutral? Correct kick-down setting? Any bad wheel bearings or dragging brakes?
If not: make a list of all suggestions presented here as possible fault sources, and cross them out one by one, as they are eliminated.

Start with the basics. As Reed pointed out, the most important is to verify your TDC. Then we have a reference point for other ignition related fault sources. When a correct TDC is confirmed, check the basic function of the distributor: when revving the engine with no vacuum hose attached, do the advance weights do their job and provide more advance? At what engine speed do they start advancing? With the engine at idle, will vacuum applied to the distributor vacuum pod advance the timing, and at what vacuum does it start to move? After sorting out these points, some member with greater knowledge of the BBS, should guide you on carburetor issues.

Olaf

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Aspenized

Hi Olafla,

Distributer is definately connected to correct ported vacuum.

It might be of interest that when the previous owner had the vehicle (and paid a number of companies to restore it), the distributer (Aussi Bosch mechanical) vac can was connected to #6 runner, the car always ran better with this setup even though we know it to be incorrect. This might also have been due to the vacuum advance port on the carb being left wide open, and the carb tuned/jetted to match this gaping hole. A symphony of mistakes that somehow all worked together. Since both carb and dizzy are different, I can't see this being relevant but I may be wrong. It does make me wonder what else might be lurking in the engine bay though.

Slowing towards zero degrees is done with the vac advance line disconnected and plugged.

I went through the same thought process as you regarding the revving being due to change in vacuum advance. The fact remains the vac can is only ever hooked to ported - I have to admit though that I don't remember whether the can was disconnected when I did the #6 test.

Will run through other mechanical issues tomorrow after I have found TDC. With that done I'll try and plot an advance curve for the car to see if it shows anything.

Thanks guys, I appreciate it.

_________________
1960 Plymouth Belvedere 4 door sedan
Stock 60 225
Push button 3 speed Torqueflite
Right Hooker

You made a point of checking the timing chain, has that been replaced recently, and do you have any idea about how the cam was timed? An incorrectly timed cam, and a badly curved dizzy, will both give a sluggishness that is not always easy to diagnose.

Can you get access to a tailpipe mounted lambda sensor for an on-the-road test?

Olaf

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Aspenized

This does not happen.
No. Manifold vacuum directly to the vacuum advance increases vacuum to the advance unit at idle.
No. Engine idle speed decreases with less advance.
None of this would affect engine vacuum and idle speed.

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一期一会
Too many people who were born on third base actually believe they've hit a triple.

A blown vacuum advance pod that was hooked to the #6 runner vacuum tree would cause a constant vacuum leak, although it wouldn't be very big. If the pod was not blown and was still holding a vacuum, then there would be no leak, just constantly advanced timing.

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Casually looking for a Clifford hyperpak intake for cheap.

Olafla - Timing chain has been playing on my mind. It doesn't seem to 'bounce' the way a stretched chain might, so not sure about that.

Given the history of work done on this car though (lots of it, not necessarily brilliant) then I don't have a lot of confidence that cam timing is accurate. I understand that not all timing sets had their dots in the right place?

I may make a degree wheel when I've got TDC sorted out and see what I can derive regarding the cam timing. What sort of numbers (angles before/after TDC, lift values, whether intake or exhaust etc) will I expect for degreeing a stock cam?

_________________
1960 Plymouth Belvedere 4 door sedan
Stock 60 225
Push button 3 speed Torqueflite
Right Hooker

...and a characteristic single-cylinder miss at idle.

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一期一会
Too many people who were born on third base actually believe they've hit a triple.

Slack chain won't cause timing bounce. Check for yourself; see here
Correct, and camshafts vary, too.

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一期一会
Too many people who were born on third base actually believe they've hit a triple.

60 Plymouth, you will find some cam specs in this thread.

I have no knowledge of whether the same cams were used in engines for foreign markes, or for engines not produced in USA, if that is the case with your engine.

Olaf

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Aspenized