Preload/pushrod length problem

CMac89

Registered User
I was having a tapping rocker problem and pulled everything apart only to find that one rocker had about .010 lash in it. I checked a couple other rocker's preload and one was about .007 preload and another was .015. Looks as if they are all over the place:eek: .

It's a "new cam" with 7.200 pushrods and I need a longer pushrod. Something sounds fishy, but I could be wrong.

So, I was thinkin, if they are all over the place like this then it seems as if I should use the adjustable rocker arms. Where can I get the adjustable setup at?

What do you guys think?
 
Some people here have perpetuated the idea that a new cam will eliminate the need for longer pushrods. This is not true. No cam is ground on the stock base circle so new cam or regrind you will need longer pushrods.

As for length, that is a function of what components you used. Valve tip heights are the first consideration, rocker arm choice is second. Shame on you Mr. 7 second race car guy if you didn't check preload on assembly. :p Just messing with ya. :)

Anyway, you do not need adjustable rockers. OE spec is .020-.060 preload so as you can see they can very well be "all over the map" and still be ok. But you def. need longer pushrods.

Did you observe rocker top to valve tip contact? That is something else to look at when setting up valve train.
 
I was just so anxious to get the car running I bolted everything down and left it.:eek: However, i'm not surprised. There isn't really any travel on the tip of the valve it stays in the middle. Looks like i'm gonna figure out what each lifter preloads at and buy pushrods for them.
 
I got lucky when i did mine. The rocker arm geometry was good and i used 7.200 pushrods and got .050-.060 preload without shims.
 
CMac89 said:
I was just so anxious to get the car running I bolted everything down and left it.:eek: However, i'm not surprised. There isn't really any travel on the tip of the valve it stays in the middle. Looks like i'm gonna figure out what each lifter preloads at and buy pushrods for them.

I didn't mean it to sound that complex. Most likely you just need to get some 7.250" pushrods.
 
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