chuck748

I did a lean burn conversion using a kit and a rebuilt/stock non lean burn carb on a 76 Cordoba with a 400. The car will not start/run unless I advance the timing way further than specs. So much so that I can't advance any more without hitting the radiator hose. The car idles and will run and drive this way, but poorly and spits back through the carb when you give it even a moderate amount of gas. I am a novice mech but hoping there was an easy answer to this? Thanks for any help!

RacerHog

Thermo Quad Carburetor???
Might have a vacuum leak...
Did you use the 5 pin control box? Or did you install a lean burn box????
Best stuff to use rite here.... http://www.4secondsflat.com/a688specs.html

chuck748

Thanks for the reply! I used http://www.summitracing.com/parts/urm-5-5170 for a carb and http://www.jegs.com/i/Proform/778/66993/10002/-1 for the kit.

I did check for vacuum leaks and found one that I plugged but it made no difference. A vacuum leak would effect the timing that much?

DDodger

i think your timing is simply wrong. how did you set it. how do you know what the timing "is"

some mopar distributors have the drive tang in different spot relative to rotor. this will change timing when changing distributors

you can just move plug wires one hole if necessary, otherwise walk dist. drive gear up with a screwdriver and change the drive gear position

chuck748

I pulled the distributor out and put the new one in the same spot. The timing is not set properly using the marks at all. The car would not start if so. I just kept advancing until I could get it to run and it is now over a quarter way around from the original spot and still needs to go more. Could the new dist be that much different? I unfortunately have no idea how to change the gear drive position but I will try moving the plug wires one hole this weekend. Is changing the gear drive position the proper fix?

RacerHog

I think I would start off "Dead Timing" the engine... Here is a example.
This concept is the same...

chuck748

This was actually done/checked already and double checked (not by me). And I am told it is correct.

RacerHog

After you get it to TDC.... Pull the cap and see if the rotor is pointing to the #1 Cap tower???

RacerHog

In That case.... I would take a guess that the Cam is not in time with the crankshaft.... Timing chain may have stretched and the gears my have jumped a tooth or 2...???

chuck748

The timing chain has less than 3,000 miles on it so I hope not! I thought of that but the car ran fine right up until I did the conversion. I think I'll start with moving the wires for now and see what happens. Otherwise I'll have to bring it to someone else as I'm not much of a mechanic and would probably do more damage than good.

RacerHog

Well... At lease you can rule that problem out...

No Intake was changed? Rite....

Just the ignition UpGrade and the Replacement of the carb with a like kind?

But in a T.Q...

Correct?

chuck748

That is correct. Ignition upgrade and carb change. I'm not sure what model the carb is but it is an exact replacement minus the lean burn stuff (an older version I think)

RacerHog

The Thermo Quad works well I think.... If there is no vacuum leaks.. And its a good solid Rebuild.. And we think the timing is set correctly. With a timing light?????...
I would have to say that possibly the Ignition might have gotten wired incorrectly... Sounds like it might have a voltage problem or the pickup wiring for the distributor might be reversed...
If you also have a vacuum gauge... Put it on a good vacuum source and see if the motor pulls at least 16-18" of vacuum.

Just my 2 cents

chuck748

Thanks for all the advice! Looks like I have a lot to check this weekend. I'll be back with results.

RacerHog

DDodger

Timing is your issue. I have no idea what you did or what is wrong. The thing is, the lean burn stuff was controlled by the computer so you cannot us that as a "relative"

There are only so many things that cause the car "not to run" on the timing marks

They are:

=========================================

The cam is wrong, either worn chain or was installed wrong

The timing marks are wrong, either from wrong parts or because the balancer slipped

=========================================

I assume you have a timing light and have checked the timing with a light?


The problem you have has nothing to do with the distributor UNLESS you are trying to use a lean burn distributor. The distributor you are GOING to use MUST have a centrifugal (mechanical) advance, and SHOULD have a vacuum advance. To determine "if" it has a mechanical advance, hold the shaft or in the engine, "spring" the rotor clockwise. You should be able to move it about 10 degrees against the spring, and it should snap back again.

Time to start thinking about checking the timing marks. Google "piston stop"