Glenn98ZM6

n/m - just need to know. did a search and found nothing.

VINCE

iTrader: (1)

I am running 7.40 with .040 milled..

Scalpel

iTrader: (4)

Vince, stock length p-rods are probably a little too long with heads mille 0.040 that can cause too much preload <img border="0" title="" alt="[Sad]" src="gr_sad.gif" />

DravenMyers

I'm running 7.40 with GTP 5.7 heads milled .030 with TR224 cam.

VINCE

iTrader: (1)

Now we have a debate.. I know of several people using 7.40's with .040 milled.. .050 I was told needs 7.35's.. When I was .060 I had 7.35's..

Brownie

I have 7.40's with my GTP 5.7L heads milled .030" and I was told by a couple of sponsors that this is fine.

Mike

Glenn98ZM6

you guys are great. thanks.

35THSSLE

What about with LS6 heads milled .030. Are the 7.40's O.K. on those too? Sorry to burst in, but like you Glenn, just looking for the almight "correct" answer. <img border="0" alt="[hail]" title="" src="graemlins/gr_hail.gif" />

Taspeed

iTrader: (1)

Ok....7.40-7.35=.050. So, to keep the stock symetry on the valve train you would idealy need to go to a 7.35 PR after your head has been milled .050 or higher. You would also want to use a 7.35 PR when you use an unusually high lift cam to gain extra VP (valve to piston) clearance.

DriveATransAm

i use 7.35 with .050 off the stockers. i have a comp cam and they are known to have smaller base circles. better safe than sorry. i tested p/v clearance with the stockers. it was too close.

Tin Indian

</font><blockquote><font size="1" face="Verdana, Helvetica, sans-serif">quote:</font><hr /><font size="2" face="Verdana, Helvetica, sans-serif">Originally posted by VINCE:
<strong>I am running 7.40 with .040 milled..</strong></font><hr /></blockquote><font size="2" face="Verdana, Helvetica, sans-serif">Vince would need 7.35" pushrods if all he did was mill the heads .040"

But, Vince has a cam with about a .030" smaller base circle than stock. That is the reason he needs to use stock length 7.40" rods.

Tin Indian

</font><blockquote><font size="1" face="Verdana, Helvetica, sans-serif">quote:</font><hr /><font size="2" face="Verdana, Helvetica, sans-serif">Originally posted by DriveATransAm:
<strong>i use 7.35 with .050 off the stockers. i have a comp cam and they are known to have smaller base circles. better safe than sorry. i tested p/v clearance with the stockers. it was too close.</strong></font><hr /></blockquote><font size="2" face="Verdana, Helvetica, sans-serif">Pushrod length won't change your piston to valve clearance unless your rods are so long as to keep the valves off there seat when they are supposed to be closed. And believe me, it won't run like that.

Whether you have .010" or .035" of lifter preload, it wont change the piston to valve distance.

QuickSilverTA

iTrader: (6)

What about 6.0L heads milled .044 running 2.05/1.60 valves. Using a hammer cam, Comp Cam 222/222 .566/.566 112lsa. I should be running 7.40's right?

DriveATransAm

</font><blockquote><font size="1" face="Verdana, Helvetica, sans-serif">quote:</font><hr /><font size="2" face="Verdana, Helvetica, sans-serif">Originally posted by Kimchee and Rice:
<strong> </font><blockquote><font size="1" face="Verdana, Helvetica, sans-serif">quote:</font><hr /><font size="2" face="Verdana, Helvetica, sans-serif">Originally posted by DriveATransAm:
<strong>i use 7.35 with .050 off the stockers. i have a comp cam and they are known to have smaller base circles. better safe than sorry. i tested p/v clearance with the stockers. it was too close.</strong></font><hr /></blockquote><font size="2" face="Verdana, Helvetica, sans-serif">Pushrod length won't change your piston to valve clearance unless your rods are so long as to keep the valves off there seat when they are supposed to be closed. And believe me, it won't run like that.

Whether you have .010" or .035" of lifter preload, it wont change the piston to valve distance.</strong></font><hr /></blockquote><font size="2" face="Verdana, Helvetica, sans-serif">please clarify. you make it sound like the length of rods have no affect on p/v clearance.

Tin Indian

As long as a hydraulic lifter is operating within its + - preload limits, it won't change piston to valve clearance.

If you have pushrods that give you .010" lifter preload, you will have the exact piston to valve clearance as if you used slightly longer pushrods that give a .040" lifter preload.

The lifter has a shuttle valve in it that can move along the internal bore of the lifter. As long as this valve/plunger in the lifter's bore is not bottomed out (by using an extremely long pushrod) the piston to valve clearance will remain the same.

Use such a long rod as to bottom out the lifters shuttle valve, then the valve wont even close completely, and during its opening cycle, it will allow for piston to valve contact.

All, I am saying is as long as a hydraulic lifter (as oppossed to a solid lifter) is operating somewhere within its + - preload spec, it won't have any change to piston / valve clearance during its opening cycle.
__________________________________________

If you [could] change piston to valve clearance by just increasing lifter preload slightly, you could also gain .020" more cam lift by simply increasing the stock lifter preload .020"
Your stock .500" lift cam would the be just like a .520" lift cam with a simple .020" increase in lifter preload.
(and that ain't going to happen)
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<small>[ October 28, 2002, 12:38 AM: Message edited by: Kimchee and Rice ]</small>

Tin Indian

ttt