Maybe a dead spot in the ICM. Have you had the ignition control modual tested yet? It may also be called a pick up coil

 

Hmm guess you missed post #3..orich

 

I know you said you were waiting til the rings seat good before doing a compression test, but I'd suggest doing it now just to be able to rule that out. See if #7 is similar in compression to the others.

 

I did see where she put in a new he I dizzy but even new parts can go bad quickly

 

Yea I think it's broken in enough to start working on it again. I'll get some new compression numbers and post them soon. Before I had it bored out I was getting readings between 120-130 on all cylinders. And they were worn pretty good. So I'm expecting even higher readings now.

 

SHE?!?! Last time I checked I still had a pair lol

 

Since you've had the problem before your rebuild you missed checking or doing something
as #7 is still running bad. Have you checked the run out of the push rods? Ez way is roll on a clean flat table with a feeler ga if needed most should not be more then 0.20ths.
What about the rockers. I guessing same cam as you did not say anything about it. So i'll throw this out if same cam did you have it check for flat lobes? I really think you need to do the compression test ,Did you read the spark plugs? no This should have given you a good idea if rings seated or what's going on with #7. Did you use fel pro pin seal intake gaskets? There's be a high failure rate using those type gaskets.. well I tired the end for now..orich

 

I know i can't understand why this problem hasn't been cured a long time ago.

There are indicators of problems in the spark plugs. All are burning properly minus 7 and maybe 8. #7 plug was black almost as if oil fouling or burning Way too rich. #8 plug was looking clean, like brand new never ran clean! But it SEEMS to be firing.

Cam is a stock replacement sealed power unit. P/N CS-667. All pushrods are new and good. Rockers are new Elgin brand stockers. 1.7 ratio.

I have new stock style intake gaskets with new valley pan gasket and I used plenty of rtv on it too. so it's sealed.

This all seems to point to ignition problems right? But on old engine and new? Original distributor, new Stock distributor and the new HEI?

Ok so it's not an ignition problem. It's a mechanical problem. Same kinda problems on original engine, and this second completely new engine? It's a totally different engine! With all new guts!

Ok so it's a fuel problem, the other 6 cylinders are burning just fine. And the carb has been rebuilt and inspected several times now. Even swapped on a different carb, same problem!

This has been my loop of thinking and doing and it just keeps looping.

Another weird fact, when my ol man parked this truck 19 years ago, he swears it ran like a top! And I can remember seeing it run.

SOMETHING IS UP HERE!!!!! It's getting very frustrating putting in all this time money and effort and not getting any results.

 

Does it EVER run right, like when you first start it, or when you rev it, etc?

 

What size carb are you running. Sorry bout the last post I goofed on that one. What color is the spark of the plug? Is it orange or blue? I have heard of the chromoly rings not sealing right. With spark plug out are you getting any blow by?

 

Once in a while it seems like it's running smooth for a few seconds, but no it runs bad all the time. Sometimes worse than others it seems to me. I don't have a choke so it's rougher when it's cold, but it always starts right up and runs. It's never quit on me it just runs like ****.

 

Considering everything that has been done, changed, etc, naturally I want to suspect something that has not been changed. How about the intake, is it possible something down in there is partially blocking the runner to that back cylinder?

 

I'm running a modified autolite 2100 carb. I believe it to be a 350 cfm unit.
It's modified because it has no choke hardware and all in used vacuum ports have been plugged. The only vacuum is the timed distributor hookup and the large Pcv hookup

 

This is my thinking as well. But no, the intake is good and clear. No cracks or anything. The carb is the only part that has been on all motors. But it has been inspected and rebuilt several times and I've even swapped to another carb for a short period. No difference. And cylinders 1-6 all burn fine.


The 6 good burning spark plugs are all tanish red in color, just like they should be.

 

Hmm now this might be interesting. I want to say that the spark was orange on 7. It was pretty weak. But I wasn't paying attention to the actual color of the lightning bolts.