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Discussion Starter · #1 ·
I’m getting a valve job and new bronze guides done on my heads. The exhaust side is getting machined up to a 1.6 valve. I’m looking at new valves and noticed that basically everything available has a tip length of 0.25, the OEM ones have longer tips. I’m concerned about the self aligning roller rockers I already have having a fitment issue hitting the retainer. I plan on running some type of spring kit to have around .50 lift safely. Is my concern about the rockers valid? Also when guides are replaced on the Vortec heads do they typically cut down the original guide boss?

Thanks,
Mike
 

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This hasn’t proven to be a problem with self aligning roller rockers with standard tip length valves. You just need to get the pushrod length correct to get the roller as centered through its travel as practical.

Bogie
 

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Discussion Starter · #3 ·
This hasn’t proven to be a problem with self aligning roller rockers with standard tip length valves. You just need to get the pushrod length correct to get the roller as centered through its travel as practical.

Bogie
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1979 Chevrolet Malibu 496-TH400-9" (cruiser). 1992 Chevrolet S10 355-700r4-7.625" (daily driver).
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Ditto on what Bogie said.

Great choice on the 1.6 exhaust valve. I think most folks would agree going to a 1.55" or 1.6" is a winner.

Generally speaking the valve spring and valve lift requirements dictate what, if anything, needs to be done from a spring pocket, guide, retainer, valve seal perspective. The first thing any good automotive machine shop does is to ask what you want done and what is the application/expectation. Increasing valve lift on Vortec heads is commonplace and a routine procedure for them.

If the roller rockers are a 1.6 ratio, mention that to the machinist. The pushrod hole in the cylinder head will likely need to be opened a little. If you have a 1.5 ratio already, you should be set.

Inquire about getting the combustion chambers "swept." They use a cutter to make a "sweep cut" to unshroud the intake and exhaust valves. Since they have the head in the machine already, it shouldn't be an expensive thing to have done. In my opinion it gives you the de facto best combustion chamber modification for these heads. It also restores the combustion chamber volume after milling the heads. I think 1 cc per .007" is a good guide for what gets taken away in milling them flat. It's not uncommon for them to have to mill .020" (roughly 3 cc chamber size loss) to get the cylinder head surface flat.

I'm a shade tree mechanic, others can feel free to correct anything, but I think it's good information to consider.
 
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