Head Identification + other questions

[athlete3344]

So, Ive been reading through a ton of threads on 1g 6 bolt vs 7 bolt heads, and I think I may have a Frankenstein head. Im just going to type out everything I noted about the cylinder, it will be a long post.

• Model - G6 with a 1 underneath it
• 1g Thermostat
• large intake ports
• The plate between the exhaust runners has a drill mark on the right side of the plate
• Both exhaust and intake studs have 2 larger studs (about 9.7mm) and 7 smaller studs (about 7.8mm).

This tells me it is a 1g head 7 bolt motor. But when I measure the diameters of the head studs, it tells me a different story (I think). I started measuring at the tear drop oil feed hole, and took down measurements following the torque sequence.

1. Tear drop oil feed - 13.52mm small bore and large bore - they are basically flush
   
2. Furthest hole away from the tear drop - 13.76mm
3. Dowel pin - 13.58mm small bore, 15.92mm large bore
4. Other dowel pin - 13.51mm small bore, 15.91mm large bore
5. Looks like no coolant/oil passes through this one - 11.96mm
6. Holes 6 through 8 are all similar, and maybe are drain holes? 12.85mm small bore, 13.88mm large bore
7. 12.77mm small bore, 13.81mm large bore
8. 12.79mm small bore, 13.90mm large bore
9. Holes 9 and 10 are similar to Hole 5 - 11.84mm
10. 11.90mm

I also have the old head studs I pulled out of it (I believe they were arp). The measurements at the ends are a hair under 12mm, but in the middle they reduce in diameter to about 10.5mm. Which head studs are these?

The new 6 bolt arp head studs I ordered are a hair under 12mm thick the whole way through.

The 3 questions I have are what head do I have, what head studs did I pull out of it, and will the new head studs work for what I have?

Thanks guys.

 

[2gmitsueclipse]

It sounds like you already figured out what head you have.
For the block:http://www.vfaq.com/mods/early-late-engine.html

 

[athlete3344]

Not really. From the studs it screams 7 bolt, but from the size of the head bolts I see 6 bolt.

From this thread,
http://www.dsmtuners.com/threads/head-identification-other-questions.483094/

Thread says all holes need to be enlarged to 0.5" or 12.7mm. Aside from the head stud holes which have no oil/coolant path (and the 6 bolt head studs do fit), they are all at least a mm larger already.

So is it a 6 bolt head, 7 bolt head, or some odd combination between the two?


Also, any idea on the what studs I pulled?

 

[19Eclipse90]

Actually sounds like the Hyundai 6-bolt head. I've got a similar head on my 6-bolt swapped 2G using OEM style 6-bolt head bolts without any issue.

As for the head studs you have, if the one end that is meant to thread into the block fits the threads of a 6-bolt block, it is a 6-bolt head stud. As you well know, it is the block that dictates what head bolts/studs are needed or to be used, not the head. In the case of a 7-bolt head on a 6-bolt block, like you've mentioned, the holes in the head need to be enlarged to 0.5". Anyhow, why the one set of studs you have neck-down or what have you, I cannot say.

 

[athlete3344]

Ill throw a pic up of the head studs im talking about later.

0.5" = 12.7mm, so I think Ill be good on all of the holes. Just thought Id post up this odd head since I wasnt able to find info about it.

1g 6 bolt head with 7 bolt intake/exhaust studs. Funny.

 

[19Eclipse90]

FYI, nothing about the intake studs designates 6-bolt or 7-bolt. That's how they all are.

 

[mercaholik]

Actually 6 bolt heads have all the same size exhaust studs. A lot of people end up drilling and tapping the outer studs for the larger 2g 7 bolt stud. There was 1g 7 bolts to, but I'm not sure what they used.

 

[19Eclipse90]

Actually 6 bolt heads have all the same size exhaust studs. A lot of people end up drilling and tapping the outer studs for the larger 2g 7 bolt stud. There was 1g 7 bolts to, but I'm not sure what they used.

I sincerely hope you aren't responding to my post.

FYI, nothing about the INTAKE studs designates 6-bolt or 7-bolt. That's how they all are.

 

[mercaholik]

19eclipse90, I was merely stating some info, athlete mentioned the two larger EXHAUST studs so I was putting my 2 cents in really. Thinking it might be helpful, no need to feel insulted so it was in regard to what the o.p. Was trying to figure out. Do you agree that 6 bolt head has all the same size exhaust mani studs? I agree with your post all intake are the same.

 

[athlete3344]

From what I was reading, all 6 bolt heads have the same sized exhaust studs. Also, if you order from studs from any website, they ask 6 bolt or 7 bolt and with the stud spec is basically all the same size vs all the same size + 2 larger ones.

I think from all my measurements, its definitely a 6 bolt head. I guess its a possibility at some point this head had a 2g exhaust manifold or equivalent on it.

 

[mercaholik]

I'm probably gonna do it to my 6 bolt head now that it's already off and I'm putting a fp race manifold on. Might get a larger(i.e. heavier) turbo in the near future and I'm hoping they help secure everything better. But why mitsu do it on the 2g heads, anyone know?

 

[19Eclipse90]

Not feeling insulted at all, just ensuring the continual flow of good information and that we are all on the same page. Yes, all DSM 6-bolt heads had equal-sized exhaust studs. It is not uncommon, however, to find larger studs on a 6-bolt due to a less than perfect repair of a broken stud. That and it isn't uncommon anymore to find 7-bolt heads on 6-bolt blocks.

 

[mercaholik]

Good, I guess I just thought you sounded upset but looking at it again I can see why you might think that I meant you, that and you can't convey tone very well with only words. Good look though there is enough mis info out there. So that being said do those two larger studs make any noticeable difference? I may not waist my time.