Thread: Determining pushrod length?

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The engine is a sbc with dart shp 180 heads. Hyraulic roller camshaft. I used the felt tip marker on top of the valve method to determine the pushrod length. I came up with 7.2 inches. My question is do I have to add or subtract from this number for the lash in the hydraulic roller lifter?? Thanks.

when you did this how did you make sure the lifter did not collapse .you had a very lite test spring .7.266 is comp retro push rods #7809-16. for push rod guides. i allways add for pre load

i did not use a light test spring. I guess I am off then. I have the test springs but I could not get off my double springs. I tried using a stud mount spring compressor with no luck. I didnt want to damage anything.

yep you need to do that and not just any test spring will work you need to fine a very lite spring .the one i use is about 030 wire or less. it can only hold valve up with rocker arm and not much more . at 1/2 cam lift read it at rocker arm with a dial gauge you should be in the middle of valve stem

ok i got of the exhaust valve spring for the number 2 cylinder and put on the very light springs I bought from jegs for $7. For some reason I cant get off the other springs. Can I use this valve to measure? Also when the intake valve for this cylinder is opening will I be on the base circle of the cam for the exhaust valve? Am I adding to the overall length of the new measurement for the lifter lash?

Originally Posted by fmg camaro

ok i got of the exhaust valve spring for the number 2 cylinder and put on the very light springs I bought from jegs for $7. For some reason I cant get off the other springs. Can I use this valve to measure? Also when the intake valve for this cylinder is opening will I be on the base circle of the cam for the exhaust valve? Am I adding to the overall length of the new measurement for the lifter lash?

can use any cylinder you want when ex is coming up the intake will be at base circle when the intake is open or bit past you on ex is base circle

if heads have been ran they can have the keepers /valve locks .take a seat you can rap the heads of the retainers to unseat them. with socket and rubber hammer make sure the valve s will not hit any thing hard . if they still can not move you better check that the springs are not to much for your cam . i used the bar tool on race roller springs that have 250.on seat and 750open

I just recheck using the light spring. I watch the lifter to make sure it did not compress. I came up with 7.15 inches. It left a nice thin line in the center of the vaave stem. How much should I add to this for preload? Thanks pat.

Originally Posted by fmg camaro

I just recheck using the light spring. I watch the lifter to make sure it did not compress. I came up with 7.15 inches. It left a nice thin line in the center of the vaave stem. How much should I add to this for preload? Thanks pat.

well most push rod s go 7.150 the 7.200 so that would be ok .or if your going to run the minum pre load for racing hi rpm then 7.150 will work