F-134 Runs rich, Backfires

hi all, I have recently aquired another project jeep and this one has the F-134 engine. The engine starts right up and runs well at an idle. It also runs good at higher rpms. The problem arises when accelerating/decelerating it seams to misfire out the exhaust at these times. The engine has a vaccum advance distributor which is probably not original. Is this my starting point to find the problem? or could it be something else with this engine?

thanks in advance.

 

Well, I have gotten real experianced with this same kind of symptom, here is a list of easy but effective things to check. In no particuliar order:

- Check plug wires! even if they look good they are a cheap replacement
- Points, condensor, rotor, and cap
- points gapped correctly? Timing?
- Coil(test it to make sure it is working correctly) and coil wire
- what shape are the plugs in?
- fuel filter
- what shape is the carb in? Could be bad float or float level

I would start there, there are other guys on here that have far more knowledge than me on this motor, so I am sure they will chime in, good luck and where are the pics!!!!

 

Thanks for the tips. The carb is in super shape. Where can I host pics to post? i am new to the forum.

 

Check that the valves are adjusted properly. then check that the carb is adjusted properly.

 

I was afraid it may be the valves or valve timing since it pops out the exhaust on both acceleration and deceleration. I am unsure of how a burnt valve or worn dist. bushings would act. Thanks for the replies. I will put a timing light on it and check the compression ASAP. And of course post a pic.

 

here is a pic of the engine
http://s836.photobucket.com/albums/zz290/ddogg1966/Jeep/?action=view&current=100_3461.jpg

 

<img src="http://s836.photobucket.com/albums/zz290/ddogg1966/Jeep/?action=view&current=100_3461.jpg" border="0" alt="">

 

A cracked or loose exhaust manifold will make them back fire too. I had heck with an old set of headers on mine one tube was cracked ,everytime i let off the gas she would backfire.

 

Where are you getting the vacumm to run the advance? From the fuel pump? The higher the RPMs the more vacumm the greater the advance. The F134 uses a centrifigal advance and the only vacumm is on the fuel pump to drive the windshield wipers.

 

I only suggest this because I was dumb enough to overlook it. I had two cylinders reversed on the distributer cap. After finding it I was amazed that it ran as well as it did with the incorrect firing order. But I had the same symptoms...fired right up, ran great at idle, ran really rich, but popped and backfired when trying to accelerate. It might be worth a look.

 

The distributor on the vehicle has a vacuum diaphragm (needs spellcheck) that has a metal tube like brake line that runs to the base of the carb. see the pic. I do not know where this dist. came from but i think i need to toss it.

 

u know i have not checked this. hehe. firing order is 1342 correct?

 

•Firing order: 1-3-4-2
•Distributor rotation: Counterclockwise

 

i cant wait to get home and check this...darn work is getting in the way.

 

consider running a vacuum gauge test and compression test should your ignition check prove no remedy.

 

#1 is in the 5 o:clock position as you are standing on the passenger side looking at the distributer.

And I notice that you don't have a working positive crankcase ventilation system and that will effect both acceleration and deceleration.

That line from the bottom of the carburetor should be a hard line that runs across the front of the engine and to the pcv or to a T that branches one line to the pcv and the other to either the vacuum operated windshield wipers, or to the top chamber of the fuel pump and then to the wipers.