Thread: 1.5 to 1.6 Rocker Change, Drilling?

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Hello everyone,

I have a set of chebby 041 heads sitting on top of my 1973 sbc motor. I am thinking of installing some 1.6 rockers on the intake sometime in the near future. Right now the setup is this: 1.5 rollertip rockers, 5/16 pushrods, and guideplates. Here comes the question.... Will I need to drill or have drilled a larger diameter hole in the heads where the pushrod thingys goes through, if I switch to the 1.6 rockers? And to what size should they be drilled to if necessary? I think I could take on a task such as this. It doesnt look to hard. Just want to know if it is needed or recommended. I thank you.

" I am thinking of installing some 1.6 rockers on the intake "

The exhaust needs more help than the intake but thats your call.





As to " Will I need to drill or have drilled a larger diameter hole in the heads where the pushrod thingys goes through, if I switch to the 1.6 rockers? " some will and some (most) won't you'll have to check and see, if you need to slot them this is the tool you'll need,




http://store.summitracing.com/partde...=KeywordSearch

Ah ha I see... ok so it might need to be done. I thought it might but wasnt sure, thanks and for the link also.

i was going to try it on the intake side then just the exhaust then both to see if I could fell which way seems to perform bettter, wish I had a dyno thingy.

I suggest you try the exhaust side first. Also, make sure you have enough valve-to-piston clearance with the higher lift.