7 bolt vs 6 bolt heads

[pony2113]

I have both a 6 bolt and a 7 bolt head, both have been removed and never marked as such. How does one identify each?

 

[ItsTwan309]

I have both a 6 bolt and a 7 bolt head, both have been removed and never marked as such. How does one identify each?

head bolt hole size. 6 bolt is larger I believe. Take some calipers and measure the ID of the head bolt holes

 

[Grd1043]

I believe that one way you can tell is that on the 7 bolt head, the bottom left and bottom right exhaust manifold studs are larger M10 studs. On the 6 bolt head they'd be all M8 studs.

I don't want to say for 100% certain because I'm a newbie as well and I've never seen a 6-bolt head myself. What I can say though is my 1994 1G is a 7-bolt, and it has seven M8 studs + two M10 studs, while the kits online for the 6-bolt heads all come with nine M8 studs.

• FP Exhaust Manifold Stud & Nut Kit for 6-Bolt 4G63
• FP Exhaust Manifold Stud & Nut Kit for 7-Bolt 4G63

 

[ItsTwan309]

I believe that one way you can tell is that on the 7 bolt head, the bottom left and bottom right exhaust manifold studs are larger M10 studs. On the 6 bolt head they'd be all M8 studs.

I don't want to say for 100% certain because I'm a newbie as well and I've never seen a 6-bolt head, but what I can say is my 7-bolt head on my 1994 1G has seven M8 studs + two M10 studs. Meanwhile the kits online for the 6-bolt heads all come with nine M8 studs.

• FP Exhaust Manifold Stud & Nut Kit for 6-Bolt 4G63
• FP Exhaust Manifold Stud & Nut Kit for 7-Bolt 4G63

This is also correct!

 

[Justin DuBois]

I have both a 6 bolt and a 7 bolt head, both have been removed and never marked as such. How does one identify each?

Intake runners are a eazy way to tell when you compare them side by side. The 1G head has larger runners than the 2G head (no such thing as a 6/7 bolt head - Late 1G DSM had 7-Bolt cranks, and ran with a 1G heads)

 

[ItsTwan309]

Intake runners are a eazy way to tell when you compare them side by side. The 1G head has larger runners than the 2G head (no such thing as a 6/7bolt head - Late 1G DSM had 7-Bolt blocks, and ran with a 1G heads)

But wasnt it a 1g 7bolt head? I thought the heads were different between them, and then the 2g 7 bolt was different as well.
Your more knowledgeable than I,

 

[Justin DuBois]

But wasnt it a 1g 7bolt head? I thought the heads were different between them, and then the 2g 7 bolt was different as well.
Your more knowledgeable than I,

For those 1992.5-1994 1G with 7 Bolt blocks, the head studs are 11mm (like 2G heads) - but the intake runners are still large to match with the 1G intake manifold. 12mm head studs are a feature of the 6 bolt crank blocks.

You can have 11mm headstud holes enlarged to 12mm if you want to run a late 1G head or a 2G head on a 6 Bolt block.

 

[Grd1043]

I was really confused by this myself when I was doing my engine which is why I poked my head into this thread. If I'm understanding you right are you saying there are three different potential heads:

- Early model 1G heads that went onto 6 bolt crank blocks (all M8 exhaust manifold bolts, larger 12mm head stud holes, larger 1g intake runners)
- Late model 1992.5-1994 1G heads that went onto 7 bolt crank blocks (M8 + M10 exhaust manifold bolts, smaller 11mm head stud holes, still w/ qthe larger 1g intake runners)
- 2G heads that also went onto 7 bolt crank blocks (M8 + M10 exhaust manifold bolts, smaller 11mm head stud holes, but with smaller 2g intake runners and other 2G bits?)

?

 

[ItsTwan309]

@pony2113
Looks like you got about all the info you need. Let us know what you come up with, and good luck

 

[pauleyman]

I was really confused by this myself when I was doing my engine which is why I poked my head into this thread. If I'm understanding you right are you saying there are three different potential heads:

- Early model 1G heads that went onto 6 bolt crank blocks (all M8 exhaust manifold bolts, larger 12mm head stud holes, larger 1g intake runners)
- Late model 1992.5-1994 1G heads that went onto 7 bolt crank blocks (M8 + M10 exhaust manifold bolts, smaller 11mm head stud holes, still w/ qthe larger 1g intake runners)
- 2G heads that also went onto 7 bolt crank blocks (M8 + M10 exhaust manifold bolts, smaller 11mm head stud holes, but with smaller 2g intake runners and other 2G bits?)

?

This is correct.