Quote:
Originally Posted by HWYSTR455
I was going to dial the idle mix screws out to 1 1/4 each, remove/move the PCV, make sure only the batt/12v is on the coil and nothing else, and verify initial timing. Maybe bring a new coil to try, and check the dizzy cap for carbon tracking.
And yes, was going to bring a tach and vacuum gauge, just so there's no question there.
Was hoping to go there tonight, but not up to par the last couple days, will have to see how I feel later.
The note Paul included on the engine was for total timing of 34 degrees, so with the 18 degree bushing, would call for roughly 14 initial. Since you can't determine the advance curve or vacuum advance needs of an engine in actual driving conditions on the dyno, those recommendation were obviously omitted.
So mentally reviewing theory, the firing order is #1, then #8, and if due to the PCV being on the #1 runner, potentially running lean, possibility of advanced timing, and the 'noise' coming from roughly the passenger rear of the engine, it's possible #8 is experiencing pre-ignition, which certainly can cause a knock type sound. Might be a stretch, but feel its worth eliminating that factor/question.
Dial-back timing lights can be tricky, have seen folks have erroneous readings, and not even realizing it.
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It seems to me you will be dealing with two situations on this engine that may or may not be related. 1. very rough idling/running engine. 2. Engine noise.
Since the "engine noise" has been reported to have been there since day 1, it is probably safe to assume it isn't hurting anything immediately, given the many times it has been run in the car and on the dyno. So personally, I would concentrate on getting the engine to idle correctly and run right. Recently within the 1060 posts, it was mentioned that the engine now has a carburetor on it that is "new" to this engine and hasn't been run or tested on this engine? When you are dealing with problems, that's a bad thing to add to the mix. In our dyno cell, we have 1 carburetor we all refer to as the "go to" carb. It is a generic Holley 750 that was worked over by BLP in FL and donated to the school. Think of it as a "dyno carb". Whenever we have someone's engine on the dyno and it's doing weird things, just not putting up the numbers, whatever the reason, we take their carb off and just bolt this thing on. 9 out of 10 times, the "go to" carb fixes whatever the problem was and makes more power. It always "changes" the way the engine runs so it gets the thinking going the right direction no matter what.
I assume you guys have whatever carburetor was on this engine when it was idling smoothly and running correctly? I would strongly consider putting it back on to re-establish a base line for this engine. Once it's running and idling properly on 8 cylinders, you can turn your attention back to problem #2, engine noise, if it's still present. Good luck with the evaluation. This is the most bizarre sequence of events I have ever heard of on a Pontiac engine. Hope you can get it solved.