Top-end rebuild; truck runs like ****

[Sean Buick 76]

No you are wrong the timing being off would cause crap performance plus you have an exhaust restriction issue by the sounds of it.

1. Remove the catalytic converter and run open exhaust from the Y pipe till you can get it running right. Your description sounds like a clogged cat.

2. Set the valves properly, it doesn’t sound like you know how to do it properly so either learn or pay a pro.

3. Set the timing properly.

If it still doesn’t run right then complete a compression check on all 8 and report back.

 

[mayvillain]

No you are wrong the timing being off would cause crap performance plus you have an exhaust restriction issue by the sounds of it.

1. Remove the catalytic converter and run open exhaust from the Y pipe till you can get it running right. Your description sounds like a clogged cat.

2. Set the valves properly, it doesn’t sound like you know how to do it properly so either learn or pay a pro.

3. Set the timing properly.

If it still doesn’t run right then complete a compression check on all 8 and report back.

The timing and valve adjustments are fine. The clogged cat is a good tip; many of the symptoms match. I will look into that.

 

[mountie]

I suspect, it isn't your cat clogged... ( As you said).... " It ran fine before"....
unless you dropped your french frys into your exhaust manifold??

 

[mayvillain]

I suspect, it isn't your cat clogged... ( As you said).... " It ran fine before"....
unless you dropped your french frys into your exhaust manifold??

Man, you and me both... I've checked and double-checked everything I touched, so now I'm just chasing down things that match the symptoms.

I looked up what could clog a cat: unburned gas from misfires (definitely happened), coolant in system (I drove with a blown head gasket)... Plus the thing is 34 years old so maybe all rough-running nonsense put it over the edge.

It's a long shot, but it gives me something to do.

 

[Vettepilot]

Well, along with everything else, ya gotta wonder if the timing chain was installed correctly.

Also, triple check firing order/plug wires are correct.

Triple check ignition timing is correct. Newbies have a terrible time getting the distributor back in right. Sometimes other mechanics too!!

Serious intake manifold leak?

Forget the symptoms, go back to basics and get everything right...

Vettepilot

 

[DeCaff2007]

Newbies have a terrible time getting the distributor back in right.

Ain't that the truth!

 

[TerryKing]

TIMING most likely, especially with new distributor installation. I had similar with a repair and terrible power. Installer had the distributor one tooth off and timing was way retarded.. Fixed and it came alive again..

 

[Vettepilot]

Ha!! I once heard a guy with a jet boat having terrible problems. Pop, fart, backfire. Stop, work on it a while, run--> same thing.

Finally, I went out to help him. He said, "I just don't understand." "I put new wires on it and everything before coming out!" "It used to run great!"

Yep, he had put the wires on exactly backwards, not knowing which direction the distributor turned. I sorted it out and MAN was he happy. I was amazed it would run at all wired that way!!

Somehow, people never stop to consider it was the last thing THEY did that is causing a problem...

Vettepilot

 

[mayvillain]

FINAL UPDATE:

Took the truck to a shop. The timing was retarded by 20º and there were 2 codes in the computer, one related to the MAP sensor and one for ignition timing.

Shop reset both the codes and set the timing to 0º and the truck runs perfect.

Thank you for all your help.

 

[GoToGuy]

Oh so close. You were advised to recheck the timing. So far off, more than the ECM could manage.
Take away: Rechecked every thing I touched and still has problem. Step away clear your head . Start over , you missed something.