340 Chugging instead of Reving

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Rat Bastid said:
That carb is black. That’s a reversion issue. Did you degree the cam? I had to ask but that’s bad.

Also, if it has so much fuel going through the engine that it blows out of the plug holes, you need to get some fuel out of it pronto. You’re killing the rings.

A 72 jet doesn’t sound outrageous but it’s getting fuel somewhere.

I can’t hear what you’re hearing but being pig rich will make them pop and bang and miss.
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Could it be the valves aren't closing, firing through the intake and exhaust.
If that be the case, there would be a lot of unburnt fuel
and misfiring.
 
fishmens67 said:
Could it be the valves aren't closing, firing through the intake and exhaust.
If that be the case, there would be a lot of unburnt fuel
and misfiring
Click to expand...
I agree and a leakdown test is the only thing left to check. The compression test had solid consistent results. I ran a dial indicator on each valve spring retainer and lift was consistent on all lobs. I may be able to do a leak test this week and I have a plate to bolt on in place of the carb to test for an intake leak on the valley side.
 
1969GTS340 said:
The jets are currently 72. It was a size I chose to start with. The plugs read that it's running rich. Black and wet. When I removed all the plugs during a compression test, fuel sprayed out of the plug holes the first few cranks. I brought the rpms up to the break up point and shut off the fuel pump. It popped until it ran out of fuel.
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The jets make ZERO difference at idle anyway, they are on the power circuit, just like the power valve.
 
I'll assume the needle inlet valve isnt stuck pushing fuel out ththe mains and flooding it?
Its firing, it wouldnt be blackened plugs otherwise..they'd be wet, maybe..but bone white if no ignition was present...or also if an exhaust valve wasnt closing..no color. Things you might do...nipple plate off the plenum...then take the rockers loose to close all valves...then pull vacuum against the intake valves. That will rule out leaking intake valves, intake seal.
Check engine ground to chassis ,plugs tight enough to break the paint and ground, box grounded, coil isnt rapid firing 'had this problem with an msd blaster before'. Does it even run good on starter fluid?
 
MOPAROFFICIAL said:
I'll assume the needle inlet valve isnt stuck pushing fuel out ththe mains and flooding it?
Its firing, it wouldnt be blackened plugs otherwise..they'd be wet, maybe..but bone white if no ignition was present...or also if an exhaust valve wasnt closing..no color. Things you might do...nipple plate off the plenum...then take the rockers loose to close all valves...then pull vacuum against the intake valves. That will rule out leaking intake valves, intake seal.
Check engine ground to chassis ,plugs tight enough to break the paint and ground, box grounded, coil isnt rapid firing 'had this problem with an msd blaster before'. Does it even run good on starter fluid?
Click to expand...

On the needle valves, with only the fuel pump running, I see no sign of fuel leaking.inside of the carb. Float levels checked and just below the site plugs.

I have a nipple plate to mount on the intake and check for leaks. I was planning to input around 7psi to listen for a potential intake gasket leak on the inside. I didn't think about pulling a vacuum but I can do that. I was planning a leakdown test on each cylinder as well.

All grounds are upgraded to 00 cable bolted to fresh ground clean metal surfaces. Box, engine and battery are tied to the frame.

Coil, I swapped in 3 different coils.

Tests that I plan to run into the weekend include:
Vacuum on plenum
Leakdown each cylinder
Change out ignition box and distributor
Possible a third carb.
 
Can you shoot a video of the engine and/or inside the car when it breaks up?
 
TT5.9mag said:
Can you shoot a video of the engine and/or inside the car when it breaks up?
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Post number 190 is a video of the engine running and at the it shows the little bit of throttle before breakup. Hard to actually hear the popping in the video.
 
1969GTS340 said:
Post number 190 is a video of the engine running and at the it shows the little bit of throttle before breakup. Hard to actually hear the popping in the video.
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I saw that but it’s just an idle video with a quick rev at the end. Drive it and video the tach and stand on it. Show us what it does.
 
TT5.9mag said:
I saw that but it’s just an idle video with a quick rev at the end. Drive it and video the tach and stand on it. Show us what it does.
Click to expand...
I have it torn down a little right now. Drying the cylinders and cleaning the plugs.
Swapping out the distributor and ignition box then putting back together. I'll shoot another video at that point. Due to finding fuel in the cylinders, I have only been test running in the shop and avoid long run times or driving it to avoid washing the cylinders and causing damage.
 
Got it. I think the distributor and box replacement might tell us something.
 
Finally Fixed !!!!!

It was trigger wires from the ignition to the distributor being reversed. I swapped them weeks ago and the engine would barley start, so I swapped them back. I didn't realize that I needed to re set the timing after swapping them. Today I reversed them and dialed it into 32* and she rips for the first time.

I appreciate all the help you guys on A Bodies provided in over 200 responses. My hope is that someone in the future that might have this same problem, finds this post and it gets them up and running sooner then it took me.
 
Sometimes you just have to walk away from it. Now go rip on it b/4 the weather takes a crap.
 
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