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New heads. Valves are different between them

crbquist

crbquist

New member
So I had a set of l32 heads p & p at a local machine shop. Turns out one of the heads was cracked so I bought a rebuilt head off rock auto. I dropped the new head off at the shop and a couple weeks later the heads were done. Upon picking up the heads, the guy at the shop told me that the new head I got from rock auto has oversized valves because the seats were not milled or something like that. He said that he just wanted to make me aware of it and that the motor will not know the difference between the two heads. Well, the heads look great and all but I noticed that the valve stems on the new head extend a bit farther passed the spring retainers when compared to the valves of the original l32 head. Is his because of the oversized valves and if so should this be okay? I just don't want any bent pushrods or anything.. See pics below

New head from rock auto:

razyguru.jpg


Original l32 head:

he3yve2e.jpg
 


L32 valves are slightly larger than L67 anyways...

But, he could have matched them...maybe he didn't care enough?
 
So with one of the heads having slightly larger valves.. Meaning longer extending passed the retainers a bit farther isn't going to mess my motor up in anyway shake or form?
 
You will more than likely need to measure pushrod length. I'm guessing that you will need a set of custom made pushrods.
 


BillBoost37 said:
Did he say the length of the valves were longer or just bigger? Longer would put you in custom pushrod area.
Click to expand...

The valves on the rock auto head are a tad longer extending a bit farther passed the retainers when compared to my original L32 head.
 
Ok, you also said that where the seat is, according to him wouldn't make a difference. Therefore maybe the seat is lower. As long as spring height is equal and total length of valve is equal then that extra extension on top wouldn't matter.
 
BillBoost37 said:
Ok, you also said that where the seat is, according to him wouldn't make a difference. Therefore maybe the seat is lower. As long as spring height is equal and total length of valve is equal then that extra extension on top wouldn't matter.
Click to expand...

BillBoost37 said:
Ok, you also said that where the seat is, according to him wouldn't make a difference. Therefore maybe the seat is lower. As long as spring height is equal and total length of valve is equal then that extra extension on top wouldn't matter.
Click to expand...

Ok that's what it is then. He said something about the seats and that is why the valve appears longer from the top. The springs are at the exact same height. I'm still learning all about this stuff so that's why I was concerned. The head is made for the motor and came pre-assembled from ATK, a reputable remanufacturing company. However the shop took it apart and aside from this valve thing, the heads are exactly the same. They said the motor will not know the difference.
 
Sounds like total length of valve is the same, spring seat is lower and the cut in the valve for the locks is lower. Rocker is going to ride the tip of the valve.

That would make sense.
 


assuming the same retainer/locks are being used here... there is something wrong... Either your springs are mounted too low (stock is 1.72 inches from retainer to head) or your valves are LS1 blanks, which will be too tall.

LS1 blanks are common in rebuilt heads... all zzp ported heads use them. ZZP also sends out shims for the rockers on all of their heads as the LS1 blanks are taller, which will require a "taller" rocker to maintain correct geometry.

ZZPerformance - ZZP Head Rocker Shims #ZZ-RSHIM
 
darkhorizon said:
assuming the same retainer/locks are being used here... there is something wrong... Either your springs are mounted too low (stock is 1.72 inches from retainer to head) or your valves are LS1 blanks, which will be too tall.

LS1 blanks are common in rebuilt heads... all zzp ported heads use them. ZZP also sends out shims for the rockers on all of their heads as the LS1 blanks are taller, which will require a "taller" rocker to maintain correct geometry.

ZZPerformance - ZZP Head Rocker Shims #ZZ-RSHIM
Click to expand...

So I would maybe need one of these, correct?
 
BillBoost37 said:
If my theory is what your guy said, you should.
Click to expand...

Called them this morning just to double check. They said it is only the stem that is thicker, not longer. And that other than that the valves are the same. They said they checked and measured everything on the heads and that they "should" just bolt on with out the need for custom pushrods, etc.
 
the tip of the valve to spring pad should measure 1.935 to 1.975.
if your in that range stock pushrod lenght is good
 
Last edited:


Chicken.. is that stock pad height or milled down for proper aftermarket spring height.

What I mean is if you measure spring height with modded retainers you'll get 1.78XX not 1.800
 
yes stock,

if someone milled the spring pad to gain more spring height, you would add that number to the stock spec,

20 thou removed off the spring pad would now mean 1.955-1.995
 
the valves have the same OAL, but your new valve have more tip lenght which would give you less spring height.
but it didnt matter cause sinking the valve job futher into the head gave the spring height height back

that what your thinkin boost?
 
Seachicken said:
the valves have the same OAL, but your new valve have more tip lenght which would give you less spring height.
but it didnt matter cause sinking the valve job futher into the head gave the spring height height back

that what your thinkin boost?
Click to expand...

So I'm good to go for sure? Stock push rods and all?
 
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