Valve guide - cut off and blend tops?

[James_Douglas]

What is the area calculation? Meaning what is the area of the valve stem versus the stem and the guild. Removing the top of the guide, how much area is picked up?

 

Or....fill a port with a valve and guide and then do another with a cut guide...with silicon fluid which flows and hardens and then pull it out and measure it...

 

Then calculate the % difference and see if it looks like it is worth it. It may be that port matching, bronze guides with tighter clearnaces and a little head porting may yield more than cutting guides...

 

James

[Bryan]

8 hours ago, James_Douglas said:

What is the area calculation? Meaning what is the area of the valve stem versus the stem and the guild. Removing the top of the guide, how much area is picked up?

 

Or....fill a port with a valve and guide and then do another with a cut guide...with silicon fluid which flows and hardens and then pull it out and measure it...

 

Then calculate the % difference and see if it looks like it is worth it. It may be that port matching, bronze guides with tighter clearnaces and a little head porting may yield more than cutting guides...

 

James

I would hope someone in the racing scene had already done flow tests with a before and after. Don't know.   Don't think just port volume or area obstruction face is the correct way to go about it.  That's why I'm asking, hoping someone has done the work.   Intakes always have flow into the valve, exhaust flows out.   On the exhaust I wonder if most of the flow is down the sides, and there is lower pressure and turbulence behind the valve face like behind a mac truck.   Plus look at the deposits in the exhaust stem area vs intake.   Don't tempt me to put on little tap on collars around the exhaust guides that blends into the port floor.  ? ?  It might be that I leave the exhaust alone and cut/blend the intake guides. Haven't decided.

Edited February 8, 2022 by Bryan

[Adam H P15 D30]

As James Douglas says above, I would cut them and install bronze liners to control wear.  Not sure if it was mentioned here or somewhere else, do not install positive valve stem seals.