Can I install 1.7 Roller rocker arms on a stock engine ?

dragbike18 · 03-05-2005

Thanks for all of your help everybody.

jason91notch · 03-05-2005

is it true that 1.7:1 rockers are worth around .038" more lift over 1.6's? if so, a stock cam (.444" lift) with 1.7 rockers (.038" more lift) would equate to .482 total lift, correct?

86Cobra · 03-06-2005

It's simple math - take lift with 1.6s and divide by 1.6 to get camlift. Then multiply by 1.7 to get lift with 1.7s. So, .444/1.6 = .2775 x 1.7 = .472.

Foxwolfe · 03-06-2005

So am I safe to assume that with 1.7's and an E cam I'll be sitting around .529 lift?

86Cobra · 03-06-2005

Yep, you're correct.

Foxwolfe · 03-06-2005

Sounds good to me, now if the damn guy I bought the 1.7's off of on ebay would hurry up and send them... bleh I hate waiting.

marks86gt · 03-07-2005

Quote:

Originally Posted by 86Cobra

Ok, guys, it's time for piston to valve clearance 101.

Max lift has nothing to do with clearance. If a cam clears with 1.6 rockers, it'll clear with 1.7s.

When either valve is at max lift, the piston is nowhere near tdc. Clearance issues occur when the piston is near tdc. When the piston is coming up the bore, it chases the exhaust valve closed and when it's going down the bore, the intake valve chases the piston. When the piston is near tdc, the valves are barely open.

If this is true, why are some pistons notched to allow for valve clearance?

86Cobra · 03-07-2005

The valves still get close to the pistons at tdc. The point is that the valves are barely open at this point so max lift isn't a factor.