How much is too much, milling heads?

[Fett]

If you have stock heads, how far is too far before you start having issues with clearance and mounting intake?

In other words, if you took stock heads and had them milled 30-thousands, used stock pushrods and lifters, and bolt-down 1.7 rockers....would you have any issues mounting the intake or any problems with the rockers hitting stock covers?

I am trying to solve a problem I ran into because one of the heads I used was milled down WAY too much. I am deciding between a few choices in replacement heads, and wonder about milling. Everything I read says that 30 thousands down is good for compression, but I don't want to run into any issues mounting the intake or having to shim the bolt-down rockers.

 

[Zero_chance]

Im pretty sure you have to take some material off the intake to match what was taken off the heads.

 

[TbonesBlack92GT]

I have read that over .020 and you should mill the intake too. I had .020 milled off of my Winsdsor Jrs. (now 53 cc) and did nothing to the intake with no problems. I am running Stage 1 cam (.499/.512 lift) with plenty of clearance.
Anything over .020 should be checked (actually, you should check it anyway).

 

[jaymac]

subscribed.
My stuff is at the shop right now awaiting instructions....

 

[Fett]

I have read that over .020 and you should mill the intake too. I had .020 milled off of my Winsdsor Jrs. (now 53 cc) and did nothing to the intake with no problems. I am running Stage 1 cam (.499/.512 lift) with plenty of clearance.
Anything over .020 should be checked (actually, you should check it anyway).

That is pretty much what I want to do. I want to take advantage of higher compression, but I don't want to get into any situations where I have clearance issues, or problems mounting the intake and causing leaks. So on one hand I just want the heads resurfaced, on the other I want to mill as much as I can without running into any problems.

 

[jaymac]

so does anybody have any solid info on this?

 

[jb89coupe]

My powerheads are milled .040". I used a gt40 intake, stock rods and rockers on them with no issues.

 

[jaymac]

sweet!

 

[jb89coupe]

The only thing to note is that the gaps at the end seals (where the lower meets the block) were pretty big. I sandwiched the cork gaskets that came with the intake set between two huge beads of rtv. I put the lower on and snugged all the bolts, let it sit overnight, and torqued it to spec the next day. So far no leaks. You also may need to shim your rockers, but no big deal!

 

[jaymac]

did you shim your rockers?
How many/what size?
Thanks!

 

[Blk91stang]

The only thing to note is that the gaps at the end seals (where the lower meets the block) were pretty big. I sandwiched the cork gaskets that came with the intake set between two huge beads of rtv. I put the lower on and snugged all the bolts, let it sit overnight, and torqued it to spec the next day. So far no leaks. You also may need to shim your rockers, but no big deal!

I also have powerheads shaved to 58cc with no sealing problems. Also the most preferred way of sealing the lower intake ends is without the cork and only a bead of rtv. Make sure when you lay down the lower intake gaskets to put rtv around the water ports on both sides of the gasket! You should be fine milling the head that much.

 

[jaymac]

what if I went to 55 cc's?

 

[jaymac]

jb89, any more details on shimming rockers before I jump in?

 

[tjm73]

No one has mentioned it, but milling the head reduces the ammount of material between the firedeck and the water jackets. You don't want that to get too thin.

Anyone know how thick the heads are in the firedeck?

 

[jaymac]

Something I didn't know... Anybody w/ a credible answer to that?

 

[tjm73]

I know if it gets too thin it can contribute to head gasket sealing problems. Especially if 'the sauce' or boost is used.

 

[jaymac]

#'s anyone?