4 replies to this topic

[CPC]

Hi Guys

 

I have a modified big valve head and a few people have mentioned about cutting my valve guides flush or down as they act as an restriction.

 

Whats your thoughts on this? this is a ported head with 37mm inlet valves and 29mm exhaust valves?

 

Thanks

Chris

[Turbo Phil]

You can blend the guide boss flush with the port roof, but do NOT grind the guide down. It will leave it far to short to support the valve stem leading to poor valve seating and undue wear.
Just bulletnose the guide from the point it enters the port. Grinding the guide flush shows minimal gains in flow and only after about .500" lift or so.

Phil.

Edited by Turbo Phil, 08 December 2016 - 10:46 AM.

[CPC]

Thanks Phil.

 

So not really worth the hassle/time?

[Turbo Phil]

If it's a decent head the guide boss will already be done, but do NOT grind the guide itself for the reasons I mentioned above. Just bulletnose the guide if fitting new ones.

Phil.

[mini13]

yep as phil says... he knows!

 

you can get away with doing it on some engines as they have long guides so plenty of support, but the A series isnt one of them...

 

this is what your looking to achive.... ironically one of turbophils heads,