Thread: Will 502 HO and ZZ502/502 use same pushrods as built by Chev?

Tweet

Anyone having experience with factory 502 Gen VI engines, know if the 502 HO and the ZZ505/502 use the same pushrods as built?
I am putting a 502/502 cam in a 502 HO and would like to use as much as possible for the cam change that I have........ looks like they use the same 3/8s" pushrods from what's available in the parts book

You will need to check the mid lift point for proper geometry---they could work with stock height heads and valve tip length

Right. Will do in any event. Just attempting to save a little time/$ if anyone has knowledge or experience. Thanks for your reply!

Originally Posted by jerry clayton

You will need to check the mid lift point for proper geometry---they could work with stock height heads and valve tip length

this is the right answer . most every thing gets the mid lift check. with the roller rocker or steel shoe rockers . many thing s come in to play for push rod length . but most all mark 6 engines will take the same push rods if hyd roller from GM with Iron heads 454to502 with stock Hyd roller cam and GM lifters stock push rods are the same. yellow paint on them i recall? i use the Trend push rods or other markers of heavy wall push rods for most all my builds .the zz502or 454 with ALUM heads may not be the same length as iron heads hard to say i have not built any of the ZZ alum head engines for some time. i know GM has a lifter for the zz cam valving is rework think less top oil . stock lifters can work but you should use the zz hyd lifter. if the stock GM roller lifters is used it should be check that oil hole will not pass lifter bore at full lift. if your using the zz cam in a mark 5 and a Retro lifters you would start out with a push rod around 7.550/8.550 long with PBM/Erson s lifters .if Comp Retros lifters there 7.728/8.684 in the short deck 454/502 block 9.800 deck. as you can see that the push rod cup is not in the same spot from comp to erson roller lifters .that is why you do the mild lift. to check the stock ZZ length of pushrods/part numbers can be check at any GM parts dealer.at this time i can not find my Gm power book .if your engine had flat lifter cam then the old push rods will not work. the short answer is if every thing is the same and if your block is a mark 6. 502 iron head engine and just a recam in your 502 to the ZZ 502 cam your old pushrods should work

Thanks for the advice and analysis. Going to go with a different cam than originally planned, now it will be a Crane # 168781 hyd roller with lift for both Int and Exh just under .600. I will go with longer than stock hyd lifters as I am past the .570 lift mark where there is the danger of the lifter dropping too low in its bore or lift too high to breech the block oil hole as Pat points out as the cam rotates. I will be using the GM aluminum perf Heads,# ---400, rec ports with 2.25 intakes and adjustable roller rockers. I will measure the pushrod lengths to be safe. Not a big track/drag engine but hopefully a decent 502 with enough stuff to pull my heavy Kingswood around with a bit of zip.......