I'm not sure what to call it. It's a 76 Valiant - 225 with automatic and no AC. It starts and drives fine until I start pushing the accelerator about half way or so, then it hesitates for a moment - sometimes if pressed down to much or too long it stalls, but then starts to take off. I have checked the accelerator pump and it's adjusted per the factory service manual - appears to be squirting properly. Timing is set to 12 BTDC per sticker in the engine compartment. I haven't been able to locate any vacuum leaks. Trying to reproduce the problem in the driveway I've noticed it only seems to happen when the car is in drive. I'm pretty sure the valve need to be adjusted (need some time and good weather) - could they cause this? I'm not sure what to check/try next.

Steve G.

One thing you'll definitely want to do is bypass the OSAC valve, if your car has one. This is located on the air cleaner housing , and has a hose running to the carburetor and a hose running to the distributor. Rework the hose routing so that the hose runs directly from carburetor to distributor. Your acceleration will get MUCH smoother and stronger.

Incurable stumble is one of the bugaboo problems that plagues the Holley 1945 carburetor...

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

It sounds like a lean stumble, that is, too much air too fast, but a timing miss can feel and sound similar. Try playing with the timing and see if you can get it to respond better. Try bumping the timing up a degree or two at a time, and see if it gets better. If you go too far advanced, you will begin to get preignition on part throttle, and then you will need to adjust the dashpot on the distributor to make it retard the timing under part throttle a little sooner. Put a small allen wrench into the end that the vacuum advance hose goes over at the distributor, and turn it to make the preignition under light throttle go away. I think you turn it clock wise to reduce the timing earlier at part throttle, but this is the kind of thing a forget. Someone else will correct me here if I am wrong. I forget the size of the allen wrench, but it is small: maybe 3/32". keep trying the small ones until you find the size the locks into the socket for it up inside. You will feel the resistance right away when you have the correct one. Dan is right, get the ossac valve out of there. It messes with the timing of the vacuum advance, and probablly doesn't work right anymore anyway.

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69 Dart Swinger, 230 ci slant, t-5 five speed, intercooled turbo, 4 wheel disk brakes, tubular upper control arms.

How old is your carburator? Sounds to me like a power valve screwup. My Ram used to have the same problem until I rebuilt my carb and discovered that my power valve had seized.

What state do you live (emmisions laws) and does your car still have the catalytic convertor on it.

My Duster has the exact same problem you are describing, except my problem goes away in very hot weather. During the winter it bogs no matter how warmed up it is.

Get yourself a timing light if you don't have one. Don't try to adjust timing by ear either.

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82 D150-225/727
02 Dakota-3.9/5 speed
87 GMC C7000-8.2 Detroit Diesel/5+2

The car doesn't have an OSAC valve, and the distributor is connected to the correct port on the carb per the vacuum diagram.

I rebuilt the carb and after several issues (I'm pretty inexperienced, but followed the factory service manual to the best of my abilities) - this is the only problem that remains. I'm not sure about the power valve - it was free but appeared to be slightly bent - where can I get a replacement? I think the carb was swapped with another 1945 at some point by a previous owner because the carb number doesn't match what's listed in the service manual.

I've got the timing set to 14 BTDC (with a timing light at idle) right now and doesn't seem to have made a difference.

I live in Maryland and the car doesn't have to go through an emissions inspection. The cat converter has been removed, but hasn't made much of an improvement except in the MPG department.

If weather permits I'll be trying out some of the suggestions this weekend.

Get a timing light on it and see if the mechanical advance is working.
You have the initial advance, then the vacuum pulls in right off idle, at light throttle and then the mechanical advance needs to "pull in".

As you give the engine more throttle, the vacuum advance "drops off", if the mechanical advance is not coming in, the engine goes "flat" or bogs.
See if there is timing mark movement when you rev the engine with the vacuum advance disconnected.
DD

All good tips. When you do put the timing light on it,and I assume you have one since you know it is timed at 14 degrees TDC, do you have the vauum advance still plugged in to a manifold vacuum source or ported? ?If you have it plugged into a manifold source, then the initial might be less than TDC depending upon the advance pot you have. When you unplug the vacuum advance hose does the idle drop? If so, it is plugged into a manifold source. If not it is plugged into a ported source, which means the advance kicks in when you first crack the throttle. If you read 12 degrees with ported vacuum plugged into the advance pot, then maybe your timing is set a few degrees too far advanced. If you are reading 12 degrees with manifold vacuum plugged in and controlling the advance pot, then maybe it is timed too retarded. The vacuum pots came with 6 degrees, and 9 degrees, depending on the years. If it is six, then you will have 12 at the crank, and this means that your initial is set at 2, if you are drawing from manifold vacuum. If you are drawing from ported vacuum, then when you crack the throttle, it will jump up to 24, which is too high.. and then come crashing back when you push the throttle further. I think the best overall resonse for a slant is to have from 5 to 10 degrees initial advance BTDC. It might still be the carb though.

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69 Dart Swinger, 230 ci slant, t-5 five speed, intercooled turbo, 4 wheel disk brakes, tubular upper control arms.

I set the timing with the vacuum hose disconnected from the distributor and plugged.

Today I got home a little early and it wasn't raining at the time, so I checked a few things. With the vacuum hose disconnected from the distributor and plugged the timing mark still advances when the car is revved a bit, so the mechanical advance seems to be working. I also double checked the which port I have the vacuum advance connected to. Removing the hose from the carb end and covering with my finger, I don't feel any vacuum until I rev it a bit which should indicate it is connected to the right port.

I am suspicious of the power valve. As I mentioned it did appear slightly bent when I had the carb apart.

I should mention though that the car did seem to run fine before I decided to rebuild the carb. I only rebuilt it because I thought it hadn't been done before (and the car is 29 years old), and might improve gas mileage. I did manage to cause some problems that I was able to fix. I had managed to damage the new rubber accelerator pump, but I bought another kit and replaced it. I also had vacuum leaks. Even though all the surfaces were clean the gaskets didn't seal well, so I used some Permatex gasket dressing. The problem I'm experiencing now is is the only one I haven't been able to correct.

I was looking at the factory service manual again, and it look like I've confused two carb parts in my explanation. The part that was slightly bent isn't the power valve - that was replaced as part of the rebuild, but it was the vacuum piston.

I also looked through the left over parts in the rebuild kit, and the are "extra" power valves. I'm pretty sure I matched it up, but suppose I could have used the wrong one. Is there a way to tell?

That replacement power valve in the kit may very well be your problem. Was the Kit a Standard Motors/Hygrade kit? That is the only kit I am aware of that comes with a replacement power vavle but it is not made like the factory power valve, throw it away.
The original factory power valve is a "gradient power valve" and has the fat part of the stem tapered a few thousandths of an inch so it works sort of like a metering rod. The replacement power valve is straight on the fat part of the stem and will not operate as a gradient power valve. This may very well be your problem. I experienced that exact same problem on my 1975-76 Valiants and the Hygrade carb kits.
You said it hesitates in your driveway at part throttle. Hold the brake hard (and butt the front bumper up to a big tree) and slowly press the throttle down to the flat spot, then keep slowly pressing and feel for a sudden power increase in your engine. This is when the power valve reaches full open. You will feel this with that piece-o-junk power valve from the carb kit. With the original gradient power valve you should not notice this action or just very slightly at most and your flat spot will not be as flat.
Hope this helps you track down the problem

Also check those advance weight like DD mentioned. Most old Mopars I run accross have the bushings in the weights gummed up with old dried lubricant and do not advance or advance and retard very slowly. Often they do not come back to full retard at idle and this causes inaccurate timing adjustments too.

The kit is a GP Sorensen 96251B from Advance Auto Parts. Anyone know where I can get another power valve without getting a another carb? I've mentioned this before - is there any reason why this only appears to happen in drive, but not park or neutral? At least that seems to be the my experience in my driveway testing.

The mechanical advance does appear to be working - see my previous post(s), but how would I go about cleaning-up the bushings in the distributor? Any chance this can be done without removing it? I've removed a distributor on a 273, but it appears a bit more difficult on a /6.

I'm leaning towards a carb problem, mostly because this problem didn't occur until I rebuilt it. I did some other tweaks, but changed them back to eliminate them as the source of the problem (orange box ECU).

You could try spraying some PB blaster down the center of the distributor shaft, but it really depends on what part is siezed.

It is not difficult to remove a slant six distributor once you know what you are doing and have the right tool. Once you've got it out, you'll have a much easier time making the repair.

I suspect that stuck mechanical advance would create a pretty notable flat spot? I suggest you fix that before messing with the carb anymore.

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1980 Aspen 225 super six

I don't think there is anything wrong with the distributor - the car was running fine when I first got it, so as they say I fixed it until it broke (carb rebuild). I'll take a swing at removing the distrubtor and cleaning and lubricating it anyway.

To get at those bushings you need to remove the distributor and completelyl disassemble everything from the top. The weights are under the plate with the pickup coil. After you remove the distributor you mabe be able to tell if they are sticking by holding the gear and turning the rotor clockwise and see if it returns, then also lightly turn the rotor counterclockwise to try and detect if the weights are not fully returning. It takes a delicate touch to determine this. Remember that old dried lubricant gets stiffer when it is cold so if you do this with a warm/hot distributor it may appear to be working.

Do you have the original power valve to put back in? That is if is the original to the carburetor.
When you are in park or neutral there is no load on the engine and your throttle is barely open. When in drive and you step on the gas to the flat spot your throttle is open much wider.

Another thought.... check that you used the correct gasket between the throttle body and carb bowl. There is at least two different versions of that gasket and the kit probably had two different ones in it. Mixing them up will cause a vacuum leak. Mixing them up the other way.. I don't know what result that will cause.