95 gsx with 12mm head bolts?

[989gsx]

I recently bought a 95 GSX from a local guy and got to replacing the head gasket. And it has 12mm head bolts. Now Im not a pro but wouldnt that mean that it has a 6 bolt head? Or possibly a whole 6 bolt swap? I have the head off still, is there any sure fire way to tell if its a 6 or 7 bolt without tearing the tranny off. Any info would be awesome.

 

[g4ebguy90]

I know a 7 bolt. Has 11mm x 1.25 head bolts. I'm going to say you got a 6 bolt BUT, I think some people have put 12mm head bolts in 7 bolts.

 

[mike96]

There is a "how to tell if you have a 6 bolt or 7 bolt" by looking at the oil pan... If the front of the oil pan has a dent in it (front meaning the looking at it the crank pully not from the front of the car) then it is a 7 bolt. If it dosent then you have a 6 bolt...

How to quickly tell a 6bolt and 7bolt engine apart

 

[98_gsx_]

If it is 12mm then more than likely it was a 1g block with a 2g head put on it. When i did my swap i used a 1g block with a 2g head and had to get the head stud holes in the 2g head bored to 12mm.

 

[989gsx]

I just checked it out. The oil pan dips in. So its a 7 bolt block with 12mm head bolts. Possibly drilled and tapped? When i ordered new bolts from the local auto parts store I just asked for "95 eclipse gsx head bolts". Ordered them, then when they came in I got curious. They are 12mm. The auto parts computer says that they are 12mm. Its no big deal. Just curious. I do have a 91 6 bolt complete motor I could compare it to side by side.

 

[1995gstr]

The 95 head has the larger bolt holes so the 12mm head bolts will drop in without taking the head off. I used 1g arp head studs with a 6bolt block and my 95 head without having to modify it.

 

[989gsx]

That makes sense. Wonder why the auto parts had 12mm bolts as the correct ones. Another one of lifes mysteries. Thanks for all the info.

Also, If it had the stock 7 bolt bottom end. I see how the 12mm bolts could go through the stock head. But wouldnt thread into the stock 11mm holes on the block. Is it common for people to upgrade the 11mm in favor of the 12mm for clamping strength purposes?

 

[19Eclipse90]

I'm amazed you actually measured the diameter of the head bolt shank! For those who haven't seen the difference in size of the head bolts, you can check this: http://www.dsmtuners.com/forums/newbie-forum/384978-stock-6-bolt-head-studs-strength.html#post152365522

I just checked it out. The oil pan dips in. So its a 7 bolt block with 12mm head bolts. Possibly drilled and tapped? When i ordered new bolts from the local auto parts store I just asked for "95 eclipse gsx head bolts". Ordered them, then when they came in I got curious. They are 12mm. The auto parts computer says that they are 12mm. Its no big deal. Just curious. I do have a 91 6 bolt complete motor I could compare it to side by side.

Not necessarily. The 7-bolt oil pan/oil pump could be modified to mount on the 6-bolt block. This is one of the more complicated methods of swapping a 6-bolt into a 2G, but it allows the original crank sensor to be used. Along with the original cam sensor you use no 1G CAS, no swapping plug wires, no swapping injector wires at the ECU, and come away with no random misfire. I'm sure it has its appeal to some.

That makes sense. Wonder why the auto parts had 12mm bolts as the correct ones. Another one of lifes mysteries. Thanks for all the info.

Also, If it had the stock 7 bolt bottom end. I see how the 12mm bolts could go through the stock head. But wouldnt thread into the stock 11mm holes on the block. Is it common for people to upgrade the 11mm in favor of the 12mm for clamping strength purposes?

It isn't something very common at all. I imagine it could be done, but I can't say I've ever heard of someone actually doing it.

Quick check for a 1G or 2G block: http://www.dsmtuners.com/forums/newbie-forum/383946-my-first-dsm-motor.html#post152352853.

Hopefully that begins to square things away.

 

[tsihottie]

I owned this car for 4 years. It was a 7 bolt for the whole time i had it. I sold it in 09 with 130k on the original motor.

 

[snowborder714]

I'm amazed you actually measured the diameter of the head bolt shank!

OP, you did do this and aren't referring to the socket size, correct? I'm not sure if the 11mm headstuds take a 12mm socket, but I know this is a common mistake when people refer to bolt sizes.

 

[donniekak]

OP, you did do this and aren't referring to the socket size, correct? I'm not sure if the 11mm headstuds take a 12mm socket, but I know this is a common mistake when people refer to bolt sizes.

This, the 12mm 6-bolt headbolts take a 10mm hex head.

You must be logged in to view this image or video.