getting heads milled, recomendations please.

[IndyBlk5.0]

ok, getting heads milled by a local shop for 135-150, this includes them being milled, and a valve job. How much should i take off of the bottom of them? Im sure they will take off whatever i ask but i want to be safe. I have crane roller rockers... not sure if they are 1.6 or 1.7... take that into concideration.. thank you!!!

 

[Mike86Stang]

big question is are you going to use boost or NOS & how much compression do you have or want?

 

[IndyBlk5.0]

big question is are you going to use boost or NOS & how much compression do you have or want?

im staying with n/a, i dont want to blow stuff up... and i want allitle extra compression, but i dont know how much i can have milled off before i have to mill my intake too... and how much would you recommend milling off stock heads, give me compression ratio and aprox hp gain if you can thanks!

 

[Michael Yount]

Remember - when you mill the heads, you reduce your piston to valve clearance by the same amount, and if you don't check it/change it, you change your rocker arm geometry with the stock length pushrods. Additionally, you change the relationship of the lower intake ports and bolt hole alignment to the ports and bolt holes on the head. If you go more than about .030", you'll likely have to mill the bottom of the intake or port match the intake/heads. You may also have to "oval" out the holes in the intake so they'll line up with the milled heads. So there are some other things to think about when you cut the heads.

 

[IndyBlk5.0]

Remember - when you mill the heads, you reduce your piston to valve clearance by the same amount, and if you don't check it/change it, you change your rocker arm geometry with the stock length pushrods. Additionally, you change the relationship of the lower intake ports and bolt hole alignment to the ports and bolt holes on the head. If you go more than about .030", you'll likely have to mill the bottom of the intake or port match the intake/heads. You may also have to "oval" out the holes in the intake so they'll line up with the milled heads. So there are some other things to think about when you cut the heads.

well what would you recommend doing then?> i am only doing this becuase my head gasket went out...

 

[Michael Yount]

First thing I'd do is talk to the machine shop. If they didn't mention the stuff that I did, I wouldn't let them work on my heads. If it were me, I'd just have them do a clean-up cut (not more than .010"-.020") -- to be sure they're level, and have them do the valve job, refresh guides and seals. How old are your springs; do they need replacing? With a minimal cut, you won't have to bother with checking anything mentioned before. If I wanted to significantly raise compression, I wouldn't do it with a head cut. I'd do it with the proper pistons.

 

[IndyBlk5.0]

First thing I'd do is talk to the machine shop. If they didn't mention the stuff that I did, I wouldn't let them work on my heads. If it were me, I'd just have them do a clean-up cut (not more than .010"-.020") -- to be sure they're level, and have them do the valve job, refresh guides and seals. How old are your springs; do they need replacing? With a minimal cut, you won't have to bother with checking anything mentioned before. If I wanted to significantly raise compression, I wouldn't do it with a head cut. I'd do it with the proper pistons.

im not going for significant gains, just doing what i can when i can. its just a good time to have just a tad taken off, i want whatever i can take off without having to worry about anything. maybe give me very minimal hp but i dont care, i dont want to mess anything up... im thinking probably .015.. will that even do anything for compression and hp? from waht i can tell springs look new like the roller rockers...

 

[Michael Yount]

The shop can test your springs when they pull them off to do the valve job - can't really tell anything about them by looking at them.

 

[IndyBlk5.0]

ok, what about how much to cut off and what hp gains to get if any, what would you have taken off?

 

[Michael Yount]

I think I already answered it the previous reply - I'd just have them do a clean up cut on mine; that way you needn't worry about any other clearance issues. A clean up cut just takes enough off to be certain that the head is true, flat and parallel to the block surface. I wouldn't expect any significant HP/compression related gains from a clean up cut.

 

[thumper460]

Cool... I have , and others , have cut .040 off and still had good interface with the stock intake! ( use RTV on the front and rear seal) cuting .040 will bump you about about .8 on compression!! BUT... like Mike said... ask the shop!! usually it is just a .004-.006 to flatten the heads for gasket seal!! IF they were to cut .020 off you will see an increase in power and compression and still be cool with the intake!! MOST valve jobs will have the heads "surfaced". to have them "milled" or "Shaved" usually means an performance enhancement and removing MORE than just enough to make them flat!! Damn words again...cool??

Just me.........................

Thumper

 

[5.0Droptop]

i would just do a clean up cut and leave it at that personnaly. Any gains will be minimal and proly not noticed in all honesty. They car has had a failing gasket since you owned it so I would jus fix it and leave well enuff alone.