440 has 2 cylinders not firing, #5 and #8 after installation

[Daves69]

Maybe compare the spark of 5 & 8 to the adjacent cylinders.

What intake manifold do you have on it?

 

[R. Everett]

Sorry I haven't responded but I think I narrowed it down to collapsed lifters. The engine sat for many years and I believe it collapsed the lifters, order new ones and should be ready to fire up again next week. Thanks for all the help, I read all of the post and it helped me in troubleshooting, I will let you guys know how everything turns out.

 

[Johnpat]

Cyls 8&5 are running mates

 

[Garys1969RR]

On some intakes those 2 cylinders are fed by the same carburetor barrel, or venturi. So I would look at the corner of the carb that feeds those 2 cylinders, to make sure the idle, or main fuel feeds are not plugged.

 

[R. Everett]

Ended up changing the lifters and still had issues, so I scoped the cylinders so I could see the valves and the valves were not closing all the way, Just barely closing so I went to 440 source and bought adjustable rocker arms then ordered the correct length pushrods and the compression went up and it runs fine now with no issues. I think the issue was the block was decked and caused the pushrods to become to long.

 

[biomedtechguy]

Ended up changing the lifters and still had issues, so I scoped the cylinders so I could see the valves and the valves were not closing all the way, Just barely closing so I went to 440 source and bought adjustable rocker arms then ordered the correct length pushrods and the compression went up and it runs fine now with no issues. I think the issue was the block was decked and caused the pushrods to become to long.

Good job!
One day I may get around to using my leak down/compression test kit.
No issues, just curious.

 

[khryslerkid]

Ended up changing the lifters and still had issues, so I scoped the cylinders so I could see the valves and the valves were not closing all the way, Just barely closing so I went to 440 source and bought adjustable rocker arms then ordered the correct length pushrods and the compression went up and it runs fine now with no issues. I think the issue was the block was decked and caused the pushrods to become to long.

Thanks for the update. Makes perfect sence.