7 bolt 11 mm headstuds?? 6 bolt 12 mm headstuds??? SOMETHING AINT RIGHT

[rabenne]

I just bought a used stock head to rebuild, I am putting a 7 bolt head on a 6 bolt block. I head that I would have to ream the headstud holes in the head from 11 mm to 12mm to accomodate the larger 6 bolt studs (or bolts if stock). I disassbemled my head and I was checking the headstud vs. the evo headgasket and it fit through... so I was relieved.

then I went to see if the 12mm arp headstud would fit through the head holes... sure enough.. fits through... Did I imagine that you had to ream the head holes?

Yes, I did verify that the arp studs were 12 mm... i dont have a micrometer for this, but it wouldnt fit in an 11mm box end wrench, yet fit perfectly into a 12mm box end.

Please help me fast!

 

[keymaster]

Chances are someone already drilled the holes on the head out to 12mm then. The 7-bolt stud holes are supposed to be 11mm.

 

[GSX26]

Chances are someone already drilled the holes on the head out to 12mm then. The 7-bolt stud holes are supposed to be 11mm.

Agreed. Or you got a 6-bolt head. Either way, as long as it fits in the threads and through the head, it'll work...

 

[luvmygst]

You could have got a 1g 7 bolt head I think they had the 12mm holes and it went to 11mm on the 2g head.

 

[rabenne]

well, the donor was a stock 98 GSX. It was a virgin, but I was in fact wrong here....

It fit through two of the holes quite snugly, but after checking again, just to see... it wouldnt fit through several other of the holes... it would start but was just too tight. I dropped my head at the machiene shop today, stainless valves, 3 angles job, hot tank cleaning, 3rd gen lifters, viton valve stem seals, mill deck for MLS gasket, ream on mill from 11mm to 12mm, and finally remove a broken off exhaust manifold stud, and replace with the new one. Should be back running again by friday, hopefully with about 450 HP

I am sorry to waste your time!

 

[donmagicjuan]

Interestingly, when I ordered my head studs for my 2G, I received the 12mm ones by mistake. When I tried to install them before I realized I had the wrong parts, the studs fit into the head holes, but (naturally) they wouldn't thread for anything. As a result, I'm not inclined to agree that your head has been modified. I would make sure I had enough clearance in the holes, however, to accommodate the thermal expansion of the head.

Edit: DOH! That's what I get for walking away from the computer.

 

[rabenne]

That is a good point though, I will be playing around with the micrometers to measure clearance between the 11 mm head bolt and the 7 bolt head bolt hole. This will tell me an acceptable clearance to ream out for the 12 mm headstuds.

Thanks for bringing up an excellent point.

 

[90gst_sean]

What sorta prices are you paying for your work? I'm about two days from dropping my block off at the shop and would like to double check the pricing. If you could price it out for each piece, it 'd be appreciated. I'm not having any head work none.

Thanks.

 

[rabenne]

mill head $30
clean and blast $60
ream 11 to 12mm $30
press out valve guides
press new ones in $50
grind valves/seats $200
remove broken E.M. stud $5