hey guys,

I just spent 1k on my GTO to get it back together. I was using stock rockers on PRC 237 heads with a 251/259 .650/.650 112 LSA cam and it destroyed all 16 valve tips.

I am looking for a good roller rocker. I have found Harland Sharps with 1.72 ratio. how much will that .02 effect my lift? Those PRC springs are rated at .675 lift but I'm losing faith in them as I've already broken one so I'm not trying to throw more lift at them.

Not trying to have anymore problems and I believe roller rockers will do the trick. All suggestions welcome.

Derek

 

T&D's or Jessel.

 

I think you have other issues if you messed up valve tips and broke a spring. There are guys who are using the stockers with the trunion upgrade on some pretty big cams.

What's the rest of your valvetrain consist of? Did you set it up?

 

my setup was PRC 237 Heads, PRC .675" Lift springs, 7.500" pushrods, stock rocker arms, ls7 lifters with i believe .080" preload on them.

i measured my pushrods yesterday, again, and came up with 7.500" pushrods like last time.

i have read stock rockers are only good up to about .600" lift then the rocker starts pulling on the valve tip causing the valve to flex a bit and possibly torquing the spring and breaking it.

derek

 

Its something else...many many threads about race engines with stock rockers. And there is threads too about aftermarket rockers beeing too heavy and they break or damage the valvetrain. There was some bad batches but still, the stockers are a goodnpiece except the needle bearings..which can be easily solve with the trunion upgrade.

 

I have 629/629 lift with double springs and stock rockers...5000miles no problem...

 

I'm running upgraded stockers on my 408 with a 255/271 .624/.624 115 lsa cam and spin to 8,000 rpms with no problem with dual springs and high seat pressure

 

I as well was wondering this same question. TSP as well recommended going with the stockers and getting the trunion upgrade. Seems like its the way to go!

 

I don't think rockers are your answer it is only going to move the problem to something else. You have a control issue rollers will just make this problem worse

Tim

 

Sounds like you need to check your pushrod length and I'd go with a set of jessels.

 

I hate the thought of spending that much money on rockers, but if/when I upgrade from stock I'm going to go with jessels

 

Everyone that chymes in on every thread only has .625 +/- a thousandth or two lift. I am at .650" lift. I'm not saying anyone is full of ****, but what if it is just a tad too much for the stock rocker? I had 2 mushroomed valve tips, and the rest had a groove cut in the middle of them where the rocker stopped pushing it down. I have read the stock rocker is only good up to about .625" lift before it starts pulling on the tip of the valve.

ive measured my pushrod length a good 3 times with the result being 7.500" at about .080" preload. A 7.475" is too short according to my calculations.

A set of Yella Terra's have been ordered. Hopefully I dont have this problem again.

A couple of you said it was something else, can you elaborate on what that could be? It could only be the rockers or the pushrods as long as the valve tip isnt soft....

 

If you are breaking springs and messing up valve tips you are loosing control of the valve and things are crashing together. Could be many different things.

Tim

 

After all the problems you are having and you go order a set of Yella terra's?!

After all the threads with breakages of their rockers? Talking about adding fuel to the fire.

 

Thats the way to go...the only way IMO.

 

Spend the money and do it right once

 

Below .630" stock works great...above .630" jessels are the Only way to go

 

And the Jesels are also heavy. Rockers are not your answer. What pr do you have
How heavy is the intake valve.

The more weight you add the more spring you need to run

Tim

 

There is a set of Jesel Mohawks [light weight] for sell on this forum rite now for $1k 1.7 ratio for cathedral heads.

 

Stock as in as they come from the factory or stock with the trunion upgrade done?