What's the thickest head gasket? 3mm?

[paul0075]

The machine shop told my mechanic to buy the thickest metal head gasket to make up for the materials were taken of the head.. head was rebuilt before..
So I'm not sure if I should buy the 3mm or the 2mm..

They already built the head which cost me $500, haven't seen the head yet.. But the shop is very familiar with the 7M head.. They said to be safe buy the thickest possible.....
Or should I be looking for different head??
any ideas guys?

 

[tlo86]

didnt they measure it?

 

[IJ.]

Paul: Measure the head from the deck to the valve cover surface when you get it back.

 

[paul0075]

didnt they measure it?

I kept telling my mechanic to ask hem to take measurement, they told him that it will need the thickest gasket possible and everything will be good... Looks like the head was already machined and had lots of materials taken off..
I showed my mechanic the options with HKS MHG, and he told me to just get the 3mm.
Is it going to be a good idea to.. have a 3mm on the engine??
I can get another head if I have to...

 

[paul0075]

Paul: Measure the head from the deck to the valve cover surface when you get it back.

What's the exact OEM measurement on the head? I don't know it..

 

[IJ.]

116mm from memory Paul.

 

[paul0075]

116mm from memory Paul.

Thank you........

 

[Doward]

Tell your machinist to measure exactly how much was cut off the head and the block.

 

[paul0075]

Tell your machinist to measure exactly how much was cut off the head and the block.

I will ask them.... But is it safe to run with the 3mm?
Is that too much to make up for?

 

[7Mboost]

It depends on how much was taken off your block and head, you add however much was taken off to 1.37mm and that is your ideal gasket thickness? (someone correct me if I'm wrong)

 

[IJ.]

I ran one with an uncut Head and Block for a long time and while it's not ideal and does strange things to the squish and economy the extra boost I was able to run without detonation more than made up for it.

It WILL make the bottom end a bit doughy though.

Your results will vary depending on how much has been removed from the block and head.

 

[paul0075]

Ok... I got the measurements for the head... Its 115 mm.
Should I get the 2mm head gasket? I'm not sure... info requested Please.

 

[Rennat]

remember thats just 2mm from the head... you have to account for the block also.

and i have a 3mm on a relatively stock head and stock block (the measurements) and IJ is right about the bottom end being doughy... but i know i wont have detonation problems relating to boost right now.

 

[paul0075]

remember thats just 2mm from the head... you have to account for the block also.

and i have a 3mm on a relatively stock head and stock block (the measurements) and IJ is right about the bottom end being doughy... but i know i wont have detonation problems relating to boost right now.

I didn't machine the block... Mechanic checked it with a straight edge and its pretty good... See my engine never overheated... and the block is in pretty good shape...

 

[Rennat]

'pretty good'.... whats that? you need NUMBERS...
i would hate to see you botch a BHG job because you dont deck the block for another $60 because the mechanic/machinist said its 'ok'...

 

[paul0075]

'pretty good'.... whats that? you need NUMBERS...
i would hate to see you botch a BHG job because you dont deck the block for another $60 because the mechanic/machinist said its 'ok'...

I never took the block out of the car...
Its been surface cleaned and straight edge checked...

 

[Keros]

I never took the block out of the car...
Its been surface cleaned and straight edge checked...

Cut it smooth and flat so that you can use it as a shaving mirror If it's already reasonably flat, you shouldn't have to remove much material to do it.

 

[Rennat]

but he doesnt wanna pull the block...

how long did you drive on a BHG???

 

[WhtMa71]

What these guys are hinting at is there's a good chance your engine is not going to seal using a MLS head gasket if the block deck has not been machined smooth, usually looking like a mirror. Sometimes they will seal but its a pretty iffy bet to take.

Now if you were to use a stock style graphite gasket, it will probably seal no problems but thats still an iffy bet and you can't make up for material removed from the surfaces.

 

[paul0075]

What these guys are hinting at is there's a good chance your engine is not going to seal using a MLS head gasket if the block deck has not been machined smooth, usually looking like a mirror. Sometimes they will seal but its a pretty iffy bet to take.

Now if you were to use a stock style graphite gasket, it will probably seal no problems but thats still an iffy bet and you can't make up for material removed from the surfaces.

The block has been cleaned and checked...
What I am really asking is, what size gasket should I get?
My head measures 115mm. is that stock? or 116mm?
Someone mentioned that the stock head is 116mm.
Also, is the stock head gasket is 1.2mm?
I was going to get the 3mm= 1mm (116-115=1mm) + 1.37mm (hg)
I'm really confused with what the actual head spec (size) is.
Anyone knows?