hg question

2543arvin

Moving to Japan!!!
Nov 30, 2006
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Jacksonville, NC
i apologize ahead of time in case this is a repost, but i searched and couldnt find it in black and white. Im in the middle of my build and i was wondering which mhg to go with and what size is appropriate given that my head and block have never been touched? thanks guys
 

tte

Breaking In - in progress
Mar 30, 2005
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Northern California
Make sure that your head and block has the required RA (Roughness Average)spec for the head gasket you use.

Cheers,
Roy
 

guards_man79

New Member
Mar 3, 2006
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Georgetown, KY
i got a tms 1.4mm metal head gasket. i got it as part of the suprastore kit. suprasport also has kits you can get. you get a metal head gasket, arp head studs or bolts and a greddy timing belt. i reccomend one of those kits.
 

jdub

Official SM Expert: Motor Oil, Lubricants & Fil
SM Expert
Feb 10, 2006
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Valley of the Sun
The Titan MHG is a Cometic...it requires a 50 RA on both the block and head deck. Roy is correct...if this spec is not met, there's a good chance the MHG will not seal. You DO NOT want to use a spray sealer on a NEW MHG. Greddy makes an excellent timing belt.

Arvin - the cylinder size for a MHG is determined if you have the block bored or not...the thickness is determined by how much material is removed from the head/block deck. You want to stay as close as possible to stock compression.
 

2543arvin

Moving to Japan!!!
Nov 30, 2006
879
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0
Jacksonville, NC
well if my cylinder size is gonna matter, then i shouldve given you guys some more info on my car. Its undergoing a full rebuild to include wiseco pistons that are .20 over. Now im already aware that the block and the head need to be resurfaced, but the RA....will that be on the MHG itself or on a paper that would come with it? sorry for the stupid questions but this is my first build, and i really dont want to have to do it again, you know?

jdub-i told the shop to inform the machinist to only remove what is necessary from the head and block to make the hg seal right.

suprahooked-the arp studs are already here, ive done enough research to learn from others mistakes.

so would a cometic MHG be a good choice? im still a little confused on what to do if my cylinders are bored. can anyone clarify that for me? thanks for everything guys.
 

jdub

Official SM Expert: Motor Oil, Lubricants & Fil
SM Expert
Feb 10, 2006
10,730
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38
Valley of the Sun
You are boring .5mm oversize...that means your MHG needs to be 83.5mm for the cylinder diameter.

If you plan on using a Cometic (yes...it's a good choice), the RA is the same as a Titan...the block & head surface needs to be 50 RA. If you use a HKS or Greddy MHG, the RA is 30. Regardless of the MHG, you want the RA value a low as the machine shop is capable of.

Have the machine shop test the head for hardness too...if it's been annealed from excessive heat, it's toast ;)