What sealant to use with a shimmed head?

[johnnyRacer]

Just got a reman. head and it came with a shim. The instructions suggest a sealant to be used but doesn't say which one. Has anyone used a shim with sealer?

 

[Brianawd]

What is the shim for?

 

[johnnyRacer]

The way it was explained is that after the head goes through its machining process for flatness the compression ratio will be higher now. To correct this a metal shim is used to bring the CR back closer to spec.

 

[turbowop]

How much did they shave off? You shouldn't need a "shim". /ubbthreads/images/graemlins/uhh.gif

 

[Brianawd]

Just use a Mitsu mls or Fel-pro mls gasket and you will be fine. Toss the shim in the trash can. Oh and tell the place where you got the head they are retards.

 

[ktmrider]

Quoting turbowop:
How much did they shave off? You shouldn't need a "shim". /ubbthreads/images/graemlins/uhh.gif

+1, find out how much meat was cut. More than 0.010" and it shoulda been scrapped.
They make different thickness HG's for just this occasion. Can't believe they gave you a "shim".

 

[johnnyRacer]

Quoting Brianawd:
Just use a Mitsu mls or Fel-pro mls gasket and you will be fine. Toss the shim in the trash can. Oh and tell the place where you got the head they are retards.



So your saying I can't use the stock Mitsu non-mls HG?

 

[ktmrider]

^^ Not saying you can't use them, just that you should find out how much the shop shaved in order to figure out the change in CR.
This is really loose but: A 0.005" shave is ABOUT like changing the head volume by 1cc. A 1cc change in volume is ABOUT 0.1 change in compression ratio. If they shaved 0.010" your static CR is now higher by 0.2 points. Could have a negative impact on your tune.
Reminder this is highly approximated. One way or the other find out how much the machine shop shaved else it's all speculation.

 

[johnnyRacer]

This cylinder head spacer shim is made from .020" cold rolled steel. Its from SBI #230-2001

 

[johnnyRacer]

I talked to the machine shop that I got the head from. They said I can go without the shim, especially since I'm planning for 20+ psi of boost. When I ask how much was shaved off he assured me that it was minimal. Here's a few pic, what do you think?

 

[slugsgomoo]

if your motor is stock 7.8:1 I wouldn't even worry about using the MLS to keep the compression lower since a bit more compression can help. I'd run an MLS soley for durability reasons with regard to knock, but only if you're going to use good head studs.

 

[Dialcaliper]

The OEM MLS gasket is thicker than the stock one by about .4mm after it's compressed (stock = 1mm, MLS= 1.4mm), which is just under .020 inches. If you just run the MLS gasket without the shim, you should be back very close to the stock compression. The MLS gasket is thicker precisely for that reason (shaving the head or block during a rebuild, without having to use a separate shim like that).

Spacing the head out a bit with it shaved that much is important, since your piston-valve clearance will be affected, and also, your valve timing will also be a degree or two off due to the shaved head, because the distance from the crank sprocket to the cam gears will be shorter by half a tooth or so.

The combination of the two could potentially result in piston to valve contact, which is bad. You might be fine if you degree it back in with some adjustable gears, but using the thicker gasket is the most foolproof way to go.

The sealer you want is Permatex Copper High Temperature Gasket Spray, or something like that, and you should use it with the MLS gasket

 

[johnnyRacer]

My plan was to use the oem stock gasket (# md183808) with this reman. head along with a set of ARP head studs and a BSE kit. I wanted to keep it somewhat simple since this was going to be the dd motor. But I'm getting the feeling that I should've purchased the Mitsu. mls gasket (# md349347). I hadn't planned on buying cam gears just yet.

 

[Dialcaliper]

The cheapest two options would be to either acquire a MLS gasket, or just go ahead with the shim and an OEM composite gasket. The first option is better, but if you aren't planning to push the motor hard (you mentioned a DD motor, I assume with a small turbo), the shim+OEM should be fine.

 

[atc250r]

I wouldn't run the spacer, period. I would preferably run the MLS gasket but if that wasn't in the budget I'd just use a stock gasket and make the most of the extra compression. Keep in mind that your cam timing will be off from the head being milled.

John

 

[johnnyRacer]

The first option is better, but if you aren't planning to push the motor hard (you mentioned a DD motor, I assume with a small turbo), the shim+OEM should be fine.



Although, I said DD I may still run this motor on weekend at the track. And I'll definately run a larger turbo.

 

[89Mirageman]

My machine shop tried to get me to do this once with a head I brought in. I went to the yard and pulled another head that wasn't warped instead and took that one to them. Sold the other one for scrap.

Wonder why they didn't call you and let you know this before doing all that work?

 

[johnnyRacer]

Actually, I didn't take this head into the machine shop. I ordered it on-line from a shop that sells remanufactured heads and you send back your core in a preaid package.

 

[Mark]

From experience especially if running high boost a mls will blow =) HKS FTW..

If they have taken to much out off the head we found that there is more of a likely chnce of he head gasket blowing also.