Which size MLS headgasket to buy?

[Devilsfutbol17]

I bought a rebuilt longblock and I decided to pull it apart so I can buy an MLS headgasket, put in some ARP headstuds, and swap some evo 8 springs in it. These are the pistons that are in it. The 0.75 on each piston means .030 over correct? What size gasket should I get? I was thinking 87mm gasket since it's for .040, but I don't know if that will work. Thanks

 

[bastarddsm]

.75 is mm so your bore is 85.75mm, I'd get an 86. More importantly, are you going to have the head and block cut? Those surfaces don't look to good.

I really think you would be better off running a composite. They will hold anything your shortblock will, and more. You'll only blow one if your tune is bad, and if you do that with a mls, it's going to break a rod or a piston......Which would you rather replace?

 

[Devilsfutbol17]

86mm okay sounds good. Yeah the block and head are beautiful, definitely just resurfaced. They just have stuff from the other cosmetic gasket on them in those pictures. I already cleaned them up though. I figure I should use an MLS because I have the option and it is better, regardless if I need it or not.

 

[bastarddsm]

Better is a relative term. I laid it out for you how it might not be better. I realize the deck was just surfaced, but its not a smooth enough surface. A mls surface should almost be a mirror.

 

[Devilsfutbol17]

I'm not trying to be rude or anything, but I googled it and found a few thread(non-dsm) that said .75 stamped on the piston is for .75mm oversized and that it is equivalent to .030". (.75mm = .030")

Also, I think the surfaces are perfect, but I'll post a pictures tonight and see what responses I get, if any.

 

[BogusSVO]

Yes .75mm = .030
.75mm X .03937 =.29475

About any gasket will fit the over bore, the fire rings are set back anyway, from OE or Fel-Pro

Personally, I think the block is to rough to take an MLS, I can see the machining grooves. But a good composite will seal just fine.

http://www.dsmtuners.com/forums/cyl...-deck-4g63-cast-iron-block.html#post152790451

I can not see the deck surface of the head well enough to make a call.

The ARP will be a good addition to your build.

I would rethink the EVO VIII springs, others have luck with them, but from what I have found, they are not much of an upgrade.

http://www.dsmtuners.com/forums/newbie-forum/341209-4g63t-valve-spring-info.html

http://www.dsmtuners.com/forums/cyl...2-evo-viii-stock-dsm-manley-brian-crower.html

 

[Devilsfutbol17]

Thank you for clearing that up for me. You can see the machining grooves clearly on both the block and the head and it looks brand new. I thought seeing the grooves was a good thing, but since its not then I guess that means I will just get a composite gasket.

I am not trying to spend very much on this motor and I already have the evo 8 springs. So figured I would throw them in while I have everything apart since they may be a hair better than stock.

Thanks for the help and info.

 

[BogusSVO]

Depending on who rebuilt the engine, you may have some aftermarket springs on it.

If you can post a pic of the springs on the head.

If you drag your fingernail across the block gasket surface, and you can feel the ridges, thats too rough.

It should be about like dragging your fingernail across a sheet of glass for a MLS

 

[Devilsfutbol17]

It was rebuild by Jasper. I just put the evo springs in it, arp headstuds, and installed a mitsu timing belt.

It does not feel like glass when you run your fingernail over it. I put a new composite gasket on.

 

[white92talontsi]

Did they really use grease to lube the rings and the cylinder walls?

I would clean that shit out and just put a very very light film of oil on the cylinders.

 

[Devilsfutbol17]

No they didn't, I put it in there while I was cleaning the surface of the block.

 

[BogusSVO]

BTW you have some unkonwn valves in the head, they maybe of a 2 piece design. I would be more worried about those than the valve springs, if you are going to try to make any sort of power.

 

[Devilsfutbol17]

Thanks for the heads up. It didn't have the sticker on it containing the tag number that Jasper gave it when I bought it, so I don't know all the details about the engine. I paid $300 for it so I'm gonna run it to hell and whatever happens, happens .