I am building a .030 over 455 and using the #96 heads. I plan on milling them .050 as well as the intake side. My question is do I have to use different pushrods other than stock?? Cutting the head would seem to change the geometry of the pushrods. Also I am running 1.65 roller tipped rockers. Is there any mods need to be taken in consideration for using these? Any info would be greatly appreciated.
You may have to enlarge the pushrod guide plate and any part of the head that the pushrod will rub when the valves are open with the 1.65 rockers.http://books.google.com/books?id=iBPFB0nDuEwC&pg=PA90&lpg=PA90&dq=grinding+pushrod+holes+for+clearance+with+1.65+rockers+on+a+pontiac&source=bl&ots=SYtCMR7Gcd&sig=A9OapT-i4WcBNtqa8oAIdMYvbfg&hl=en&sa=X&ei=t4GGU-v8BcXisAS9-IDQAw&ved=0CH8Q6AEwCQ#v=onepage&q=grinding%20pushrod%20holes%20for%20clearance%20with%201.65%20rockers%20on%20a%20pontiac&f=falseFor the pushrod length. you'll just have to install a pushrod and rocker. Adjust it like you'll be running it and see where the center of the roller is on the valve tip. If it is near the center of the valve tip, then you may be OK. If it is well off center and will roll further off as the valve opens, then you may need shorter pushrods.http://transamcountry.com/community/index.php?topic=47061.0;wap2If so, you can buy an adjustable pushrod, made for this purpose. Keep adjusting it til you get the length you want. Then measure it and buy the length that is closest to what you need. Since the amount cut off the heads and the deck, plus any difference the rocker may cause, plus the cam itself, can all inter into the mix, there's just no way to tell for sure without checkin it. This one might work. Not sure.http://www.summitracing.com/parts/cca-7704-1/overview/
Thanks for the info!, Tim
You have the right idea about cutting the intake side of the head the same amount as you cut the chamber side, so that any original or out of the box intake will fit your motor. If you cut the intake manifold itself, then that manifold will not fit any other motor, unless the heads have been cut the same amount as yours. Also, if you decide to buy a new intake, you'll have to get it cut before it will fit. I'd hate to pay $250 for a new intake, then have to take it to the machine shop and pay them more to cut it before I could use it. It just makes no sense. But the choice is yours. http://forums.highperformancepontiac.com/70/8532676/drivetrain-upgrade/milling-heads/http://www.hotrodders.com/forum/milling-pontiac-heads-196323.htmlhttp://www.78ta.com/HTAF/index.php?topic=24971.0Now, where you can really run into problems is when you have a mismatched block, heads and intake that have been previously cut down by different amounts. And to make it even worse, what if your heads came off 2 different motors(or more) and were cut different amounts. Hey, this could turn into a machinists nitemare !
your push rods will rub on the heads when the valve is closed!and yes you will need shorter push rods.
76 455/4spd TRANS AM69 GRAND PRIX 455/5SPD