1985 4.3

[TheRealDylan]

I have a 4.3 v6 that is mainly stock, except for an HEI distributor and edelbrock carburator from JEGS. I know the 600 cfm is overkill for this engine. Although when it first got the truck, it was running well with this setup. I am not sure what changed, but it has 0 power and won't go over 35, even with the pedal to the floor. It has a weird sound when giving it gas. It is running at 12 degrees of timing.

Driving Video

Park

 

[idahovette]

converter plugged???

 

[TheRealDylan]

converter plugged???

I don't believe so, but I'll check.

 

[TheRealDylan]

Not plugged, ordered a fuel pressure regulator. Will install and see if that helps.

 

[xm20k]

Timing or fuel if all of a sudden it has no power is where I'd start.

I have owned a few of the carbureted 4.3s and I've never worn one out (they never lasted that long) I have had 3 of them all break the crank 1 even still ran on the rear 3 cylinders but the front 3 did nothing because it separated at the center two rod journals.

 

[TheRealDylan]

I have a gauge coming on Friday, so this weekend ill be able to check fuel pressure. I have 4 degrees of timing, have tried 12, 8, 6. I ended up with 4 since that's what the engine calls for.

 

[TheRealDylan]

Was only getting around 2 psi of fuel pressure. Put on a new fuel pump and get around 6 now. Still having the same issue. I am not sure if this bog is due to fuel, or timing.

Here is a video of it running

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[Ricko1966]

Timing or fuel if all of a sudden it has no power is where I'd start.

I have owned a few of the carbureted 4.3s and I've never worn one out (they never lasted that long) I have had 3 of them all break the crank 1 even still ran on the rear 3 cylinders but the front 3 did nothing because it separated at the center two rod journals.

The front still had to be turning,the front turns the cam,the cam turns the distributor. I've gotten an engine or 2 in at work in the past with broken cranks that were still running.Its amazing when you see it.

 

[xm20k]

The front still had to be turning,the from turns the cam,tge cam turns the distributor. I've gotten an engine or 2 in at work in the past with broken cranks that were still running.Its amazing when you see it.

Correct had to be the front half still firing, just remember tearing it down and finding the crank split in two like wtf.

 

[TheRealDylan]

The front still had to be turning,the front turns the cam,the cam turns the distributor. I've gotten an engine or 2 in at work in the past with broken cranks that were still running.Its amazing when you see it.

How would I check this with leaving the engine in the truck? Compression test?

 

[Ricko1966]

How would I check this with leaving the engine in the truck? Compression test?

I'd check compression first. Is the engine making any funny noises? I wouldn't immediately be looking for a broken crank yes it happens but it's one of the rarest forms of failure. Checking for a broken crank,I'd wedge some towels or wood blocks into the flex plate to hold it solid. Then try to rotate the crank back and forth at the balancer,it'll be a listen and feel deal. Also put one hand on the flex plate stick a pry bar behind the balancer and pry it forward feel for the flywheel and balancer to move together,pry it back,pry it forward and feel. Now switch ends move the flexplat and feel the balancer. This will be easier with the plugs out,so do this while you are running compression, I seriously doubt you have a broken crank.

 

[xm20k]

Mine broke when running it quit moving and ran rough and made a clanging noise, was obvious it was broken.

Compression test then look at the ignition system and fuel delivery.

Was the eddy on it when you bought it? Wondering if previous owner washed it down a few times trying to get it running that carb is a bit on the larger end for that engine but tuned right could be fine.

 

[TheRealDylan]

I'd check compression first. Is the engine making any funny noises? I wouldn't immediately be looking for a broken crank yes it happens but it's one of the rarest forms of failure. Checking for a broken crank,I'd wedge some towels or wood blocks into the flex plate to hold it solid. Then try to rotate the crank back and forth at the balancer,it'll be a listen and feel deal. Also put one hand on the flex plate stick a pry bar behind the balancer and pry it forward feel for the flywheel and balancer to move together,pry it back,pry it forward and feel. Now switch ends move the flexplat and feel the balancer. This will be easier with the plugs out,so do this while you are running compression, I seriously doubt you have a broken crank.

The engine runs smooth, no galloping, no weird noises.

 

[TheRealDylan]

Mine broke when running it quit moving and ran rough and made a clanging noise, was obvious it was broken.

Compression test then look at the ignition system and fuel delivery.

Was the eddy on it when you bought it? Wondering if previous owner washed it down a few times trying to get it running that carb is a bit on the larger end for that engine but tuned right could be fine.

When I got the truck, the Edelbrock came with it. Before it had the Q-Jet. I put the Edelbrock on since all the electrical connections for the Q-Jet were removed, and the computer. I do see that this carb is big for the truck. I also put on a (JM6520R HEI Distributor w/ Super Cap, Chevrolet V6 (220, 229), Red) when the carb was installed.

 

[Old Guy Bill]

The front still had to be turning,the front turns the cam,the cam turns the distributor. I've gotten an engine or 2 in at work in the past with broken cranks that were still running.Its amazing when you see it.

Where I work maintenance we've got a Clark 4 cyl fork truck the crank is broke in one journal. One end of the crank has 10-20 degrees of rotation play, it still starts but hasn't any power because of the timing.. weird as hell.