heads

[doitnow]

I have a 90 231cui v6 with modiiified Stage 0ne Supercharger and water/alcohol injection and nitrous. My question is how much can I remove from the head surface before I get the valves hitting the pistons?

Old Guy.

[The Old Guy]

How big is the cam? Does it have the stock lift,? What is the duration ?

Are the valves stock or oversize?

[JohnD1956]

Recalling a recent tour of a local machine shop, I think the question to be asked is how much material can be removed before affecting flow. Closely followed by how will removal affect the flow.

[NTX5467]

Other than generalities, the ONLY way to check is to put some soft modelers clay on the top of a piston and turn the crankshaft several rotations to let the valves open and close several times, then take the head back off and measure the thickness of the clay after the valves opened and closed against it. Doing this will have "some disassembly required, some re-assembly reauired" in the mix, though, but will take care of any build variations in metal thickness on your cylinder heads and other engine parts for YOUR engine in the process.

Plus, it can be possible that your engine might have had a valve job somewhere in its past. Usually, many shops that do valve jobs also "surface" the heads in the process . . . whether by "rotating rock" or lathe (unspecified amount with the former, specific amount known in the latter).

Regards,

NTX5467