Quote:
Originally Posted by TRADERMIKE 2012
I just got through looking at STEVE BARCAK mod and 1A2 Block cooling holes and 421 style cooling holes, I see that the 421 mod holes are not in the Head nor the Block. There are additional 3 holes that I would have to plug in the Block per side, I see that the factory did close 4 holes per side on the Block on mine. Plus, I need to drill the holes in the Block and heads between the two exhaust valves.
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This is a picture I drew of the Pontiac cooling Mod. that I found on this forum, I have drawn it in the pink marker, I am seriously thinking of incorporating this modification as I have the Heads remanufactured. My roommate and I are Leary about doing any other work than sealing off the exhaust crossovers at this time and we need to degree wheel the cam. Since I don't have the crossover exhaust "X" and the vehicle always ran without it tells me that I don't have to add one if I just go back the way it was.
It is noted that the 80 degrees of overlap with these "041" cams is a lot of OL. However, I can always buy a set of Roads Lifters and 1.6:1 Rockers later, again this car ran with the Johnson lifters in the past. we think that the 80 degrees OL having the Intake and Exhaust Valves open for that duration coupled with holes in the exhaust crossovers in the Head, plus, lack of proper mufflers and having the 2-1/2" Exhaust Pipes running some 10' to the Diffuser could cause this noise, that I never had, except on several recent test and tunes.
We are willing to take our chances, as we always have, to do what we think will work, the worst-case scenario is that we have to go back into this motor. At this time, I feel that the Pistons being reversed did not cause this issue, so why would I touch them at this time? This motor is strong at the bottom and if it is not broken don't fix it. Someone knew what they were doing when they modified this motor. Although the factory does things for a reason, so do the racers. Since no one has explained to me why the crossovers "X" is installed, after the collectors makes it hard for me to make my decision. " Why do people use an "X" type crossover abaft of the collectors"? Note: this vehicle has been running less that 10 k miles since I got it running, with the Exhaust system going from the Headers to the collectors and Streight out to the diffuser, with no problem ever. I have very few miles on this "041" Cam and I had installed it with the advanced timing just prior to the Transmission accident, thus this Cam could have something to do with the current noise issue?
Because I had the vehicle off the road for 2 years building the Trans. So, People who are telling me that I must use the Roads Lifters, I ask is this current noise the product of 80 degrees overlap, because if that is what you mean by saying, get Roads Lifters than I have to agree with you people. Please bear with me as I learn something, this is out of my league. Believe me, for those of you who are steering me toward the piston change that won't solve the current issue, duly noted. After I squeeze the life out of the bottom end of the motor, then I will rebuild this motor, as stock using new Rings and all new Bearings. This engine already has had all the other replaceable parts installed, then sell it to someone that needs a Pontiac YK code 428 HO with Tri-powers and I will buy a modern Engine like one of those 1AII with Aluminum Heads and all the goodies.
08-09-2023, 03:54 PM
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