Popping around head area on my 440, only really at idle... ???

[jenkins71]

Hi guys,

So my 440 runs pretty good, 2000 miles on the build. It is fairly low compression, around 8.9. Comp XE 274 cam I believe.
At idle, the is a sort of rhythmic splat, or pop, kinda loud around the head area on the passenger side. And sometimes on the driver's side as well. My motor like a lot of initial timing, around 28*. Mech advance is limited to 10*, 38* total. I can advance it pretty high, and it runs even better at idle... like, i can advance it to 40* and it runs even better (of course I wouldn't keep it at that setting).
Now, when i advance it to 40*, the random at-idle POP, which you can hear from the passenger compartment btw, goes away. It also kind goes away as you drive it faster.

Any idea's what is wrong? Hoping for a leaking header gasket...

 

[miller]

Suggest starting with a compression check. Could be valve overlap, or a cam timing issue.

 

[jenkins71]

I should add that it is something that has only recently come up...

 

[mmissile]

I'd start with the headers for leaks.

 

[eric383]

Take a 3' piece of heater hose and put one end to your ear and use the other end to try and isolate where the noise is coming from. I was thinking header leak also.

 

[Cranky]

Had the same thing happen on a 383 years ago but it had nothing to do with compression. It was a hair over 10 actually but I would check what your cranking PSI is. If it's pretty low, it's probably why it likes a lot of timing. Low compression engines usually do respond well to a lot of initial and total. So long as it doesn't experience pinging, give it what it likes. Anyways, mine was leaking header gaskets.

 

[1wild&crazyguy]

header leak or really low compression for that cam.

Nothing built with a 'matched' combo should need more than 28 degrees initial imo.

 

[jenkins71]

Ok so the header bolts were "finger loose"... tightened them and the noise went down a little i think. But the gaskets must be blown if they were that loose.
I have some Remflex (basically gaskets made of a big piece of graphite) gaskets. I guess that is the next thing to try.
Are regular old header bolts okay to use?

 

[kowalski]

Remflex is great. I'd want some stage 8 locking bolts myself. At least use some blue loctite and don't overtighten.

 

[jenkins71]

Great news dudes. Put the reflex gaskets on, as it is like night and day. PHEW! The noise had gotten so bad, I was starting to think I had a bent pushed or something! The old gaskets were visibly blown out pretty badly.
Thanks for any input.

 

[eldubb440]

unplug each wire one at a time...... if it is a header leak you will find it