6g74 - What gasket did you use?

[Gearheadvr4]

For a 6g74 that's already built what head gasket would you use. What if you have a larger than stock bore of 93.2. How do you bore out a stock head gasket to match?

If that's to much trouble then would you guys recommend a Cometic gasket? They make an oversized gasket for a 6g72 that works with a 6g74. The stock mls 6g74 is not for use on a turbo car.

http://i429.photobucket.com/albums/qq12/gearheadvr4/39d7f645.jpg

http://i53.tinypic.com/2hd70ow.jpg

[Ninja Performance]

OEM HGs, chamfer pistons.
I would stay away from the Cometic. It's a 3 layer versus the OEM 4 layer.

-Chris

[Chatzvr4]

OEM HGs, chamfer pistons.
I would stay away from the Cometic. It's a 3 layer versus the OEM 4 layer.

-Chris

+1. we just chamfered the pistons with a mls 6g72 gasket

[IPD]

i'm with those guys ^.

i intend to do the same with my stroker build.

[Gearheadvr4]

If I used a factory 6g74 which one do I need? I thought they wouldn't work because they are too thin and not really for turbo applications?

Unfortunately camfering the pistons is not an option. The block I'm looking at is already professionally built. The block is a diamante-style non-crossover 6g74 block (out of a kia) with 20 over Ross pistons.

[Rocket]

[quote]Using the wrong gasket and then chamfering the pistons is a bit pointless to say the least. But then if you haven't done your homework to find out what's available it's to be expected.[\quote]

Steve, I find the rest of your post to be pretty informative. This snippet though could be left off and you wouldn't rub so many raw even when you have good information. I don't personally know you. My guess a cantankerous old SOB that is just pretty gruff about everything. You have some good information to give sometimes, but the blunt attacks just cloud the issue and worthwhile things then get overlooked.

If there is an option to actually use a correct OEM MLS gasket I would think that would be much better than camfering pistions, but both are options that can be considered.

Steve, since he is .020 overbored will either of the stock gasket scenerios you listed work for him?

[Gearheadvr4]

The pistons are Ray’s custom Ross 6g74 pistons – 20 over, supplied by Scott Merkel. Block was Line bored to 2.6775. Does that help any? I don't know yet what any other measurements are.

No worries about offending me. It would take a lot to do that. No I have not done my homework at all. That's why I'm here to try and correct that.

[Ninja Performance]

I'm sure Ray will know how far out of the block these pistons sit. As for the size? these motors are designed and built in mm not inches.

so 2.6775 comes in as 68 and a bit mm........?
Maybe it was 3.6775 inch, that will be 93.4085mm .
20 thou over is roughly .5mm (.508mm)over the stock 93mm so should be 93.5mm.
In this part of the world we got rid of inches years ago. We buy oversize pistons in multiples of .25mm 10 thou inch is .254mm. It confuses things un nessecarily.
Line boring is actually align boring, which is what is done to main bearings (the block). Bores (cylinders) just get bored.

Realistically you can't rely on anything on the net, you need to do your own measuring or you get the wrong information.

Steve

Do you post sillyness just to see if you can get away with it? Seriously? I really wish you would stop before someone takes your info as fact. And you are correct, you can't rely on everything you hear on the net....ringlands.

-Chris

[Gearheadvr4]

I will try calling Ray and get his opinion. He's built a couple of these with those pistons so he would probably know.

The line bore info was just what I was told. Odd to me also that it was in inches. I don't have the block yet so I'm unable to make any measurements. I didn't think it would be so difficult to just get a couple of gaskets. Damn!! :(

Edit: Well I got up the nerve to call Ray and he said they chamfered a lot of those pistons anyways and he explained how I would be able to tell. So I'm back to waiting till I get the block in to see what I have. From the information I got from the seller,i dont believe they were chamfered. Since they are probably not I'm still in the same situation and have absolutely no idea what to do and cannot go forward till I figure this out.

[zelstin]

I will try calling Ray and get his opinion. He's built a couple of these with those pistons so he would probably know.

The line bore info was just what I was told. Odd to me also that it was in inches. I don't have the block yet so I'm unable to make any measurements. I didnt think it would be so difficult to just get a couple of gaskets. Damn!! :(

I'm sure Ray has the answers you're looking for, he's done more 6g7X strokers than anyone on the planet. Whether the info on the block is in standard or metric just depends on the machine shop that did the work. No biggie.

[Ninja Performance]

You just don't like other people having differing opinions.
Maybe you could point out what's incorrect about my measurements?

Using a stock 72 gasket on a 74 block (with chamfered pistons ) puts part of the gasket (sealing ring) inside the bore space. That's a no no with engine building, it's likely that the unsupported sealing ring will get too hot and potentially cause detonation/preignition so the end result is another failed mod.

Steve

You better call ray and clue him in then. You may save him from ringland failure. Thanks

-Chris

[GTO]

On my 6G74 I am using the stock 6g72 MLS turbo head gaskets. The top of the pistons have been chamfered to fit the 6g72 gasket. My bottom end was built by Scott / Ray and was one of the earlier setups so if your pistons are newer than 3 years then I would assume they are chamfered. Scott and Ray both said to use the stock 6g72 gaskets as they appeared to be the best option at that time. You will be able to tell looking at the top of the piston, there is just a little bit of material removed from the outer edge.

EricC

[Gearheadvr4]

If the block is already completely professionally assembled, how difficult is it for a first timer to pull it all apart and put it back together the same?

I understand where everything goes and I can get the stock torque specs from the manual. Few things I don't understand yet...

1. How are the pistons rings are stacked on the piston? I assume the openings of the rings are offset somehow?

2. Everything has been miticulously plastigauged. Do I need to put all the bearings and pistons in exactly the same spot again? If yes, what would be a good system to keep track?

3. If I am just removing the pistons, how much of the block can I leave assembled? What I'm saying is, can you release only the piston from the rod from the bottom of the block and then push it out the top with the rod still on the crank? Is there enough room to do this?

[Ninja Performance]

If the block is already completely professionally assembled, how difficult is it for a first timer to pull it all apart and put it back together the same?

I understand where everything goes and I can get the stock torque specs from the manual. Few things I don't understand yet...

1. How are the pistons rings are stacked on the piston? I assume the openings of the rings are offset somehow?

2. Everything has been miticulously plastigauged. Do I need to put all the bearings and pistons in exactly the same spot again? If yes, what would be a good system to keep track?

3. If I am just removing the pistons, how much of the block can I leave assembled? What I'm saying is, can you release only the piston from the rod from the bottom of the block and then push it out the top with the rod still on the crank? Is there enough room to do this?

First off, plastigauage is good to get a ball park idea where you are at. For true measurements you (your builder) should use mics.

Piston rings are put on with the gaps across from each other, that is detailed in the shop manual (Ninja Performance Shop Manuals (http://www.ninjaperformance.com/3SManuals/)) and with the piston/ring pack you get.

No, you can not separate the rod from the piston while in the block, the rod cap is removed and the rod with piston comes out the top of the block.

-Chris

[Ninja Performance]

Plastigage is for ricers .

A micrometer and bore gauge is what pros use, in mm. Definately not in inches.

Steve

Please, STOP being retarded. It does NOT matter what you measure in. As long as you are consistent. It does NOT matter if you build a 3S using inches. It does NOT matter what unit of measure you use.

-Chris

[Gearheadvr4]

It probably was done with mic measurements. The pictures I have of the plasti-gauging were probably just to show that the bearings are correct.

This is the block I have -- 6g74 built 3.53L

- Fully worked 6g74 block that had only 12k original miles on it. Line bored to 2.6775” using ARP main studs. Decked to a very high finish. Bored and honed with a pair of torque plates and ARP head studs. 0.005” piston to wall clearance.
- Ray’s custom Ross 6g74 pistons – 20 over, supplied by Scott Merkel
- Ray’s custom ring pack – already file fit, supplied by Scott Merkel
- Pauter 6g74 rods supplied by Scott Merkel
- Ray’s tool steel wrist pins supplied by Scott Merkel
- Spiro-locks
- New ARP main studs
- Forged 6g74 crank – custom heat treated to be approximately double the strength/fatigue resistance of a oem 6g74 crank. Cryo treated following heat treatment. Crank has been straightened and has 10-under journals on rods and mains. Finished by one of the best crank shops around.
- New King main/rod/thrust bearings matched to the crank. Designed for 0.002” clearances on mains and rods using King bearings. Slightly looser or tighter tolerances can be had using clevite (looser) or oem mitsu (tighter) bearings.
- 6g74 oil pan (not modified)
- 6g74 lower intake manifold
- 6g74 long block misc parts/pieces (timing, oiling, cooling, etc)

$4.5k into in parts and labor

[Gushers]

Just curious if the SOHC oil and coolant galleries line up with the DOHC ones. Do you think the Montero MLS would hold up to the cylinder pressure with a turbo'd car?

[Gearheadvr4]

I think it would be fine to use on low boost. It may only be a 3 layer design.