I agree with alot of what you stated Rich, and you could be accurate in your analysis, HOWEVER, to convey your suggestion/prescription for remedy may be suicidal, IF indeed the problem is retarded advance. I'd suggest verifying the ignition advance, er.. retard first. Don't care for the smell of fried pistons.

 

my problem being similar to this one in that i seem to have unusually high egt at and just above idle even with a/f @14.5 verified with wide band on board and dyno. i checked fuel press., checked timing against a timing light and the list goes on. i ended up advancing the cam with a cloyes adj. timing set. motor picked up 50 hp and lowered egts a little. i'm wondering if the large heads and cam combo is just very inefficient at low rpms causing poor atomization of fuel and therefore still burning in the exhaust?
side note:egts don't get abnormal at wot w/ a/f of 12

 

Did you verify what the timing was set at, to begin with?

 

ignition timing? - yes. i got true TDC using a piston stop then made my own timing brkt and checked it against a light.

 

No, valve timing. You stated you advanced the cam. You advanced it from where it was. Where was it, to begin with? If you didn't know/check where it was, how do you know if you didn't actually correct it to where it should have been in the first place, ie, according to mfr's. specs.

 

i really did not know where it was other than dot to dot and the specs off the cam card. it was more of a trial and error thing i felt i had a valve timing issue so i advanced it and figured if that it got worse i would retard it.

 

My new motor has been doing this along with an annoying backfire at any high vaccum situation... (like slowing on the highway).

Its super annoying and I can't find anything unusual with the datalogs. Plug wires have been checked... valves have been readjusted..

I don't know.. pisses me off though