I have a set of stock LS6 heads w/Comp 918 springs. I had the heads cleaned and milled .015. I will be using stock GM head gaskets and am planning on getting a Patriot226 cam. My question is I have Comp 7.4 pushrods, since I had my heads milled and will be using stock size gaskets, do I need shorter pushrods or will my 7.4 be ok to use?

 

7.4 should be ok. i had my heads milled .010 and when i asked texas speed what to use, he said the 7.4 would fit no problem at all.

 

yeah it should be fine, but your goin to be in teh loose side of the specs. if its niosey after your finished, you could go with 7.425 to tighten it back up.

but looser is better then too tight.

 

Also remember that the base circle on the cam is smaller, so that will be a compensation for the milled heads.

 

You should be fine. I'm gonna be runnin 7.4's on my 5.3 heads milled .030 with a 224/.581 cam. Only difference is I'm gonna run gaskets that are .041 compressed, not stockers.

 

big mike, your gonna need shorter pushrods for sure. my setup is similar to yours. milled .033 and .040 cometics, on comp cams small diam.. anyways, I came up with needing 7.350 (which actually measures out to 7.375". or about .021" shorter then stock. TSP's company measures there pushrods diff. then just end to end for some reason.
and, thats a bad *** pic in your sig. how do you guys make those damn things?

 

Thankx, I had another member make it for me.

I talked to Jon@TSP, Gunnar@Patriot & Bo White about the heads, rockers & pushrods. All of them said I'd be fine with 7.4's, but it I milled any further, I'd have to change them.

My heads are gonn be:

5.3 heads ported/polished & milled .030 by Bo White
stock seat/retainers/locks
comp 918 springs
Thunder Racing 7.4 pushrods (stock length)
stock 1.7 rockers modified by Harland Sharp
also throwin in some LS7 lifters

And the of coarse the .041 compressed gaskets. You sure there aren't any differences in the LT1 & LS1 that could have caused you to need different length pushrods??

 

What head gaskets measure .041?

 

I can't remember the brand I'm gettin but they are from Autozone & the part # is: 9284PT, they are special order. Several local guys have had great success with them & they are only $17.99 each instead of $70 each like some.

I know in the Jeg's catalog there are some from FelPro I believe that are .041 compressed also. They are just more costly.

 

Fel Pro 1041's are .041 thick.

I'm kinda interested in the Auto Zone gasket.

Bob K.

 

well, the engine Im talking about is in my dads TA that I just finished. see my thread in the dyno forum about that.

when you get the heads all together and go to tighten down the rockers, just do yourself a favor. set up one of the cyl.s at tdc (easy enough to set that up before you set the head in place), figure out which one of the two cyl.s that are at TDC is on the compression stroke (both lifters will be down, so the cam is on the basecircle and not lifted)and proceed bolting on the heads. then set your rockers up on the cyl. you know is at TDC compression stroke and finger tighten the rocker nut until you reach zero preload (no up/down play in the pushrod, and the nut will get alot harder to turn since your compressing the lifter). pay attention to how many turns you get out of the nut before you start torqueing the nut. stock is around 1 full and a 1/3 turn. mine setup around 7/8 of a turn cuase I wanted close to .060" - .080" preload. stock is around .120".
if your over 1 and a half turn, the pushrod is too long.

and, what material is that autozone gasket made from? $20? sounds too good to be true. you should mic the gasket before you put it on. see what the thickness is before being compressed.

and, Im pretty sure the felpro's are not .041 thick. I looked into that before I bought the cometics cause I wanted to get them. some of there books are conflicting and some say .041", and some say .054" or something like that. thats when I just said screw it and went with the cometics.

 

Those are Felpro's too, I have a pair here now....and some new GM bolts....

 

PM sent my friend.

And thankx for the install info Irocss85. I'm glad I'm not doin it all by myself. I got a buddy from our local club that is gonna help me do it all at his house. He has done all this before & then some, so that'll help.

 

Bo, what are the felpros? are they really .041? whats the part #? how much? thanks. I'll keep this on hand for future builds.

chris

 

The Felpro 1041s are .041" thick but they have a 4.100 bore I think(on both accounts), the Felpro 9284PT that I have here are .061" uncompressed so I dont know how much they flatten out when they are compressed.

 

just measure bro. i ended up having to use 7.0 pr's on mine. no where even close to what i thought i would need.

 

you even got it back together yet man?^^^^

 

ended up having to order a new rocker from harland. i got it yesterday (thursday). i just have to button-up the pass side of the motor and start her up.