ItalianZ28Stallion

iTrader: (3)

I bought a set of the stainless comp pro magnum roller rockers and every time i adjust them like comp says, my car will not start. I believe its the vavles staying open and this is why the car wont start. Do i need shorter pushrods? Someone must have had this issue to.

2000PewterT/A

Do a leakdown test to confirm the if the valves are staying open.

vettenuts

iTrader: (4)

Not familiar with Comp's procedure but if they are stud mounted rockers, the pushrod length adjusts both the wipe and the preload so be careful changing length.

You could try Vinci's procedure that they developed for the Crane rockers to see if that works better. Over adjusting will hold the valves open. Also, zero lash is critical in adjustment and I prefer to gently lift the rocker tip to check clearance rather than rotating the pushrod. You could also use a very thin (0.002") feeler gauge between the valve stem and the rocker tip to set zero lash. This will result in minimal error in the final setting.

supergt99

iTrader: (1)

when i had comp promagnum they adjusted like a smallblock chevy. assumuming you have the correct pushrod length, you adjust preload by the adjusting nut. i was giving 1/2 turn after 0 lash.

onefast84

X2 on the sbc way. Ive had mine for 6 years with out problems. 1/2 turn after 0 lash!

ItalianZ28Stallion

iTrader: (3)

the pushrod length is 7.400 and i did a leak down and the vavles are staying open. I also adjusted them like a old school with 0 lash and a half turn and the motor wont fire.

ItalianZ28Stallion

iTrader: (3)

what is your push rod length and have you done any bottom end work. Cause i have 11.1 domed pistons and 243 heads

JPH

iTrader: (2)

when the Exhaust Valve just starts to open= Adjust your Intake rocker (0 lash, half turn)

when the intake valve is 3/4" of the way closed= Adjust your exhaust rocker (0 lash, half turn)

0 lash= no up and down movement in your pushrod.

ItalianZ28Stallion

iTrader: (3)

i did that and it doesnt adjust right. There is no way for me to move the pushrod the correct way. So how am i spoose to check the lash?

JPH

iTrader: (2)

EASY, you can feel it with the polylock. As you turn the polyock down clockwise, you can feel right were its loose still and then gets tight all the sudden. THAT is you point of "0" lash.

ItalianZ28Stallion

iTrader: (3)

hmm ok ill try that. Thanks ill let you know what happens

JPH

iTrader: (2)

yep no problem.

vettenuts

iTrader: (4)

Who determined the pushrod length?

The Cranes required a 7.250" pushrod due to the rocker design. If you are using 7.400" because of its closeness to the stock length, then you need to determine the correct length which is a bit more difficult because the length sets both geometry and preload.

supergt99

iTrader: (1)

Make sure the lifter is on the heel side of the cam. No lift. Then do your lash adjustment.

ItalianZ28Stallion

iTrader: (3)

how am i going to check that the motor is in the car and im not going to take off the head to check that. ill have to contact comp to see what size pushrod is recomended

vettenuts

iTrader: (4)

???

Are you referring to the pushrod length question or cam position? Both can be done with the motor in the car and heads on.

ItalianZ28Stallion

iTrader: (3)

pushrod

vettenuts

iTrader: (4)

You will need a set of check springs and a vernier to measure the stud depth, do you have these tools?

ItalianZ28Stallion

iTrader: (3)

comp said i need none of this.

vettenuts

iTrader: (4)

Typically Comp tech support. Good luck.