Help, engine hesitation problem


I have a problem with a newly owned 1967 Dodge Dart (6 cyl)

The car has a hesitation problem. At low speeds, such as doing about 10 mph and the accelerate to 25. The hesitation happens mostly at these lower speeds while going round residential streets. If I floor it at the lights, it's ok, If I'm going on to the freeway it's ok.


It sounds like the classis accelerator pump not working on the carb.

But I replaced the carb (with a good one from Recarbco) and it still does it.

The someone told me it must be the distributor, so I replaced this ..and it still does it!!

Any ideas ?? I have tryed the garages, but they just want to do expensive engine analists.

I have some mechanical knowledge and have done some of my own analist.


Compression is good around 140

All plugs are firing

Fuel is under pressure

I even put a vacume gauge on it. And it pulls a low 16, which is in the normal engine zone. But the needle does ossilate a bit.

The timeing is set to 5 advanced and is steady


Any Ideas ? ? ?? ?

What's the dwell/point gap? Vac pot on distributor good? How's the valve adjustment? PCV valve? What's the fuel pressure read? Junk in lines/pickup? 16" vac seems pretty low for a stock /6. Is that in neutral or in gear? I'd hope for about 17" steady in neutral, but that'd also depend on the idle speed.

"DW"

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If it ain't broke, fix it!

i'm sittin' here with a busted keyboard so expect typos.

1. the 1bbl /6 hesitation is much worse with a dirty (or damp) air filter. please check and replace.

2. check timing and dwell one more time. 5btdc is about as little as you can get away with - without a flat spot. i run 10btdc, but can't run 87 octane gas (89 works).

3. rebuilt carb = a leaky throttle shaft normally. there is a workaround. replace the stock pcv valve (fram 163) with the mopar 4 banger model (fram 231). about 1/2 the airflow, it can make up for some throttle shaft leakage but can be messy if the engine has alot of blowby.

4. tweek the accelerator pump settings. i find that slightly more volume, slightly slower/longer action, helps.

5. removing the vacuum advace (and plugging at each end) also helps, but very slightly. if it helps much the line or can is leaking.

6. my combo is timing at 10btdc, tweeked accelerator pump (holley 1920), and fram 231 pcv. no flat spot so long as i change the air filter every 6000 miles.

Paul

It sounds like the jet in your carb is to small. You probably have a #55 or around that in it now. Step up to at least a #60 jet, that should cure the problem. The jet is on the bottem of the metering plate, just right of center (toward the "economiser" valve). Advancing the timing will raise the vacuum some. Right now my stock '72 slant (with Holley 1920) has a #62 jet, 11 degrees BTDC timing, 9" open element air cleaner and stock PCV with one of them open breather caps. Sounds like a healthy engine, just needs a little tweaking.

>>It sounds like the jet in your carb is to small. You probably have a #55 >>or around that in it now. Step up to at least a #60 jet, that should cure >>the problem. The jet is on the bottem of the metering plate, just right of >>center (toward the "economiser" valve). Advancing the timing will raise >>the vacuum some. Right now my stock '72 slant (with Holley 1920) has >>a #62 jet, 11 degrees BTDC timing, 9" open element air cleaner and >>stock PCV with one of them open breather caps. Sounds like a healthy >>engine, just needs a little tweaking.

i know nothing about the jets (sorry). its a factory 225 /6. i just figured out how to make it work with trash gas and 30 year old carb holley. changing main jets to deal with what i see mostly a 'controlled' manifold leak (worn throttle shaft seems to be the largest change) seems extreme. perhaps i don't understand. i am mostly trying to keep things working, its an stock '65 dart '170' 2 door sedan (225 /6, auto tranny, manual steering and brakes). it works well - and i enjoy driving it. hopefully i didn't do anything i shouldn't, my combo has worked for me for the last 10 years.

Paul

- still typing without a working keyboard

This reminds me; what's a good jet to use for about 600 feet ASL? Is the factory jet sufficient?

If I keep working on the Dart, the carb is on the "todo" list.

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'74 Duster w/ HEI ignition, beat to snot suspension, A904, 8.25" 3.55 SG rear, still being tuned up and gets 17 MPG

Know how they always build a better idiot? That's me