Head gasket opinion question

[frosh29]

Here is an opinion question for you guys. I am in the middle of my first full rebuild. I purchased a Cometic metal head gasket for the engine, but my machinist did not deck my block. Needless to say it isn't a mirror finish. My head was resurfaced. I also have the stock hg at my disposal. I am wondering what I should do, figure out a way to deck the block (by the way bottom end already assembled)? Should I go with the stock gasket? Any opinions would be great.

p.s. I have 9:1 pistons in the block and ARP studs. Again, any feedback on the dilemma would be much apprecated.

 

[dsmputz]

Well either your machinist is a total retard and you need to go back there and slap him around, or he checked the block and found it sastisfactory. Regardless its always a good idea to shave it when dissasembled especially if its a performance build. As to the mirror finish i've heard of lots of guys on here taking some light grit sandpaper and giving it a little rub. You should call your engine builder and ask him if he actually checked the block surface for peace of mind.

 

[talon187]

I would at the very least call him if not tell him you want it decked anyway i would if i were you. the thing about the metal headgasket is that everything needs to be totally smooth for it to seal correctly ive got a mitsu 4 layer myself. the stock gasket will seal better if its not totally smooth because the metieral isnt so stiff like the metal one. id get it decked and call it a day better safe then sorry

 

[BUCK]

Just do a Search on COMETIC & you'll QUICKLY see you want to leave it alone & why talon 187's advice to go with the 4 Layer is the ONLY way to go - Unless perhap$ you are just into PAIN - Good Luck

 

[frosh29]

So is the 4-layer more forgiving?

The only problem with getting it back to the machine shop is that he would need to disassemble the entire bottom end to deck it.

I have taken sand paper to the block, but it did not make a mirror finish at all (I used 1500 grit).

I appreciate all the help.

 

[BUCK]

So is the 4-layer more forgiving? .

yes.

 

[frosh29]

sweet...thanks for the info....p.s. I do not like pain, but that is somewhat inherent of owning a DSM....

 

[dsm-onster]

You'll likely leak w/ the MLS heag gasket. You don't have both surfaces finished. Both cometic and MLS head gaskets should have a prepped head and block. I've seen both get away w/ just the head prepped in spme instances. But, considering the effort, why chance it? I've seen too many fail w/ just one surface prepped.

You'd be better off w/ a stock composite headgasket w/out both surfaces done right. Besides considering the larger diameter of the head studs neccesary for a 6bolt block, you'll likely be capable of some surprising results w/ a stock head gasket. Jsu besure to torque to the proper sequence and stages and use the proper torque specs for which ever lubricating media you're using. Don't forget to properly heat cycle and then *properly* retorque (this means backing the nuts off 1/4 turn then retorquing). I torque my arps to 120 ft-lbs w/ 30 wt. motor oil. I've run significant boost and seen significant airflow numbers w/ a fel-pro (oem composite) headgasket.

 

[talon187]

i say deck the block you be happy at the end ive seen the metal ones leak without the block done if your not going to do the block put a stock one on and hope for the best because you'll be pulling the head off again if you use what youve got without decking the block

 

[frosh29]

These are all good answers, and I thank you all for your opinions.

I am currently planning to put the stock gasket on for now. I am not interested in running significant boost yet. I will in the future, and will also take the proper steps to get the block and head prepped for action. (I guess this means I'm going to have to build another motor on the side )

I will be following all of the necessary procedures in the final steps of this build. The worst/most amateur thing about it is the block not being decked. The rest is top notch. If, however my first HG fails, you better believe that I will be disassembling, and decking the block and head until they are perfectly flat and smooth.

Again, thanks for the opinions.

-Scott

 

[GVR4592]

The factory finish on the block is usually better than any machine shop can do. The head is where the problems are. Even if your machinist resurfaced the cylinder head, I'd be willing to bet it's not up standards for a MLS gasket.

 

[frosh29]

Thank you gvr4, I feel the same way. I don't fully trust this machine shop, even though he was pretty cheap. I'm going to hope the stock head gasket holds strong with the ARP's. I cannot wait to find out (and possibly rip the head off if this HG fails). sick

 

[dsm-onster]

The factory finish on the block is usually better than any machine shop can do. The head is where the problems are. Even if your machinist resurfaced the cylinder head, I'd be willing to bet it's not up standards for a MLS gasket.

Hey, Luke. I believe you mentioned before that the block has to be prepaired for a MLS headgasket. And that it's easy to contaminate the surface just by touching it. Since you all are saying a machine shop will likely make the deck worse, what preparation is required? And who can do it?

 

[talon187]

ok i should of said this before. Before you put that gasket and head on take a level to the block and see if its wraped bad or not if its wraped bad well then you know you need it decked you can buy alittle disk at autozone to help clean up the surface. if your going to sand the block make sure you use a sanding block or you can cause it be uneven

 

[GVR4592]

Hey, Luke. I believe you mentioned before that the block has to be prepaired for a MLS headgasket. And that it's easy to contaminate the surface just by touching it. Since you all are saying a machine shop will likely make the deck worse, what preparation is required? And who can do it?

All I'm saying is it's very difficult, sometimes impossible, to find a local machinst that can get the block smooth enough for a MLS gasket. Factory finishes are far superior to what most local machinist's can do.