Stock valve seat room?

[2slow4utsi]

So I don't understand why most shops that build our heads will bore out the seats to fit 1mm oversize valves and other shops tell me there is more than enough room to fit 1mm oversize valves. I need some information on this and whether or not I should have the shop bore out the seats or go to another shop that ensures there is no need to bore out the seats to fit the valves.

Thanks,

Danny

 

[e85_4g63]

1mm over sized valves will easily fit with the stock seats. They'll (seats) have to be cut so the valves seat correctly though. If your machine shop can't do a simple valve job like that, take your parts else where. I don't see any reason to bore the seats, I'm not sure I'm understanding 100% of what your trying to ask though. Can you reword your question for me?

 

[My1GLaser]

I have +1mm Ferrea valves in stock valve seats. Probably a waste of money since people are in the 10s and even 9s on stock size valves.

 

[2slow4utsi]

"We bore out the seats a bit and squeeze in 1mm over Supertech black Nitrided SS valves on both sides with under cut stems on the intake side for added flow." That is straight from FFWDConnection. Not only did they say they had to do this, DSMGraveyard said the same thing. I don't know why my machine shop would say it's pointless to do both the boring and undercutting but then again they know more than me. They have done many heads for the 4g63s.

-Danny

 

[e85_4g63]

When Darren said bore on his website, I think he was reffering to cutting the seats for the valves. Under cutting the valves help keep the volume and velocity of the air up while entering the cylinder. Are you asking if you need to have the seats cut for the 1mm over valves or if you need to get new seats? You will always need to do some sort of cutting of the seats when replacing the valves with larger units. No matter what engine there going on (unless it's a valveless engine, like a rotary).

 

[2slow4utsi]

I was told there is no need to bore cause there is more than enough room to fit the 1mm valves. The reason I asked this in the first place is cause the shop I want to build my head assure me that what FFWD does is not necessary...hence why I wanted more opinions from tuners.

-Danny

 

[Defiant]

It sounds like you may be getting confused between removing and replacing the seats, and simply cutting them the ½mm for oversized valves. Ask your machinist to make it clear, and if he wants to replace the seats, make him explain why. Make sure it's not only for the extra $20 a hole.