Cannot Get Dauntless To Run Right. Misfiring/backfiring Even After Complete Tune Up

I am pulling my hair out trying to get my dauntless to run like she used to. Its a 69 motor, it sat in a barn for twenty years, i resurrected it and it ran beyond belief for probably 8 years. Now it backfires out the driver side exhaust at idle and misses at high speed. The only other clue i have is, upon starting it, i have to cycle the choke in and out, over and over to keep it running

Ive given it a complete tune up. Points, condenser, rotor, cap, plugs, wires, fuel filter,carb rebuild.

Ive sprayed everything with both starting fluid and propane and cant find any vaccum leaks.

Compression check yields between 115 and 140, with the driver side (backfiring side)at 125, 125, 130.

Dwell is perfect, timing is at 5*. I have noticed the timing mark seems a little erratic under the timing light. Not sure if thats attributed to the oddfire or if i need a new timing chain. Or is it possible i could have a valve stuck closed?

 

"...is it possible i could have a valve stuck closed?"
Valve sticking open is more likely than stuck closed, I would think.

Checked dwell with a meter, does it vary or wander? = Possibly worn distributor shaft making point gap (and timing) erratic?

The choke thing makes me think of intake air leak. Checked all the vacuum hoses, etc?

 

Sounds suspiciously like a vacuum leak. I would start with disconnecting vacuum ports and plugging them. Things like vacuum advance canister can cause a vacuum leak that can be hard to trace. Also, maybe the carb has issues like a loose body, etc. sticking valve(s) are also possibility or collapsed lifter. Flat cam lobe possible also although you would think it would show on the compression check.

 

vacuum gauge will tell you lots too.

 

I agree, i have been 99% sure that this is a vacuum leak this entire time. But I cannot find it for the life of me. I will unplug everything and block it off. My vaccum is lower then its ever been. I use a vaccum gauge to tune my carb over and over and my vaccum is right around 15lbs at idle.

Dwell is perfect and does not wander. I have a rebuilt distributor, but was still suspecting it. I took it out and compared it to a known good one and everything seems just fine.

I am thinking I will try blocking all my vacuum lines and if that doesn't work go ahead and pull the heads. I am not at all experience with internals of motors and appreciate all of your advice as to what in there can be causing this.

 

Double check for the correct distributor cap for the oddfire motor. I had the same symptoms when I brought mine home. An even fire cap was in place.....drove me crazy troubleshooting it.

 

When did you install the reman distributor ?
Is that when the problems started ?

 

No my jeep ran great for several months after installing the distributor. Original issue with it was the lobes wore out and snapped off for the mechanical advance. I will check the cap

 

compression is low . but when you did tune up . are you sure that you placed the wires in correct position and order on cap

 

Yes i meant 15 inches of vaccum im sorry. I always srsrt with the adjustment screws 1.5 turns out. Then go out then in to find the highest vaccum.

Since it only backfires out one side, does that mean the issue is probably in the head?

I can't remember the difference between an even fire and odd fire distributor cap. I've been searching but can't seem to find the info right now.

 

excepting the fact your back-firing side is within 5psi of each other, I would suspect a piece of carbon or crap in the seat area of one of the exhaust valves. Unless it spits back through the carb, then the crap is in the seat area of one of the intake valves.

 

caps for odd fire DR61 RR184 and the D326 RR189. The only diff I can see between these two caps is the window location is slightly diff. If you can insert the allen tool properly then it should work.

 

The backfiring is possibly being caused by a lean fuel condition. With the motor running take a spray bottle with gasoline in it, and squirt a small shot into the driver side Venturi and see if there is any improvement. If it isn't a vacumn leak it may be a restriction in the carbureter. Mine was plugged so badly the passenger side wouldn't run ,it would just backfire.

 

what about a cracked exhaust manifold allowing more air in on the driver side and leaning out the mixture? or failed manifold gasket on driver side

 

its possible that your backfiring out the exhaust and the missing are 2 separate issues. I had one of my 4 cylinders missing at high rpm so badly it wouldn't do go anywhere at high rpm. turned out I had installed the spring for the points incorrectly. I just flipped the spring around on the points and was all fixed. may be something to check. I know for me, these old machines have taught me a lot I didn't know before since I hadn't owned anything with points before or all this old technology

 

Hi everyone, i wanted to close this post out and say i found the issue. The problem ended up being the brake vacuum booster that i have from a wrangler. Once plugging that vacuum line off, my jeep runs smooth as silk (especially after almost two complete tune ups chasing the problem). I sprayed carb cleaner everywhere trying to find a vacuum leak but it was completly internal. Thank you everyone for your help!

 

Good to hear !

 

I just went through almost the same thing on a new engine I installed, ran great then I changed to a different manifold and carb and could not get it to run as soon as I put it in gear, knew it was a vacuum leak, but since I removed the dist., I had to check all the options of what I did to make it start running bad, I chased it for a month, (just when I had time to fool with it) I was about ready to pull the engine, when I sprayed around with gas in a spray bottle by the carb, made it run faster, had to be something there, but no, reseated the intake two times? then again with the gas, same thing, finally I put a rag down by the back of the carb to clean up some of the fuel and that did it. So on the very back of the new offy intake, just below the carb, where you cannot see it, is one more small vacuum port that I did not plug off, I thought how stupid I am, all that work chasing this and just a unplugged small port? Now if I spray the carb with fuel, it slows down, as to much gas, so no other leaks!

Rick