Let's see, how's that old saying go?...there's never time to do it right, but there's always time to do it twice.

Chris

 

From a personal experience, milled heads and an 847 "can" need shorter rods. Ask 96ta(nick) he chewed through a set of guide plates and then spun a cam bearing out of the block. (with 7.2 pushrods)

Check it!

We checked mine before putting the motor in the car. With the cc306 I am going to go a tad shorter than stock, but use 7.2's just to get it running until I can order some 7.1s.

 

yeah i think im going to just go with 7.150's less wont hurt as much as too much..plus im taking .050 off anyways with the smaller headgasket and shaved heads

 

How did you use the checking tool to determine the length? Did you use calipers at any point?

 

I love this saying!

Proper pushrod length is going to help make the valvetrain work properly AND not wear out the guides. Too short of a pushrod will develop problems of valve control around the seat which usually hurts power badly.

Bret

 

I just talked to LE..he said I could just go with the 7.2's Which is what im going to do..i cant wait..i got a heated garage to work in now..alls I need is more days off to get this beast going.

 

If you don't want to take everything apart you can use one of the length checkers from Manley (available from Jegs) and an adjustable pushrod and it will get you very close. The part is only about $15 and is easy to use. There are also clear and detailed instruction on how to use it on the net if you Google "pushrod length checker".

Jim

 

This is what Lloyd emailed me when I ask him the same question.


"I have mocked up stock bottom ends with my heads and my cams (4.960" length valve, milled .010-.020, stock block deck ht and Impala gasket with my cams and the base circle I use and the lift of my cams). I know what THIS set up needs.

Any time you change ANY of this stuff and use diff valve length, valve job depth, changing head castings, milled diff amounts, diff block decking, diff head gasket thickness, cam base circle, cam lift, etc, etc, etc, you really need to mock it up and see what it looks like.

Start by using some "test" valve springs so the real valve springs do not compress plunger in lifter and throw things off. Color in top of valve with black market and rotate engine over by hand a few times. Look at the wear pattern on top of the valve and see how "centered" it is. Adjust pushrod length .050" shorter and re test. Keep adjusting pushrod length in .050 increments until the wear pattern is most centered.

"Most" set ups need a stock 7.200" length and if they vary at all it will be only .050" shorter or longer.

This is the ONLY way to KNOW what pushrod length you need."

Lloyd


Heard you got a good deal on those LE2's Good luck......John

 

I C-clamped two short lengths of scrap 3/4" angle iron to my bench, with the stock pushrod between them and squared up. Then using my Comp Cams #7702 Hi Tech pushrod checker, I adjusted it so that it was identical length to the stock pushrod. When it was the same length, I just counted the number of turns it was out from the fully retracted position. Each full turn is 0.050"; 6.8" + (7 x .050") = 7.150"

Chris