ARP studs too big for head?

[adollarwodbnice]

Well, after literally a full month of having the head off I finally got my buddy's tap and die set and I was able to get the last ARP head stud in. I go to drop the head on and it goes on maybe an inch....

I tried several different ways to make this work and it just would not go down. So, I took my spare head that's completely bare and it dropped down perfectly. Pulled a stud out to check tolerances and sure enough my bolt holes are too narrow for the ARPs... even stock bolts I had on were kinda tight.

The spare head I had was from either a 90 or 91 but I have no idea what my head came off of.

Does this mean I need to get a different set of ARPs? Do they make different thicknesses? I'm tempted to go with stock bolts because they will fit but I don't wanna blow another head gasket.

Not really sure what to do at this point since I just spent 250 to have my built head decked, hot tanked, fully reassembled to proper specs, pressure tested, and is completely ready to be dropped on...

 

[nuclearr]

Sounds like you may have a 7 bolt head. I would take it to a machine shop and ream out the bolt holes in the head. I think the 7 bolts are 1mm smaller than the 6 bolts.

 

[adollarwodbnice]

Now this kinda puzzles me... does this mean I have a 7 bolt block too... couldn't I just get 7 bolt studs so I don't have to drill out the head... like I said I just spent 250 to have this head properly machined and it essentially doesn't fit because the bolts are too big....

 

[nuclearr]

NO. If your studs are for a 6 bolt and they threaded in then you have a 6-bolt block. 7 bolt studs are smaller and will strip out or pull out under boost.

 

[adollarwodbnice]

UGH... things you wish you ####in' knew like a month ago....

Thanks....

 

[donniekak]

Run a 1/2" drill through them, from the deck side.

 

[adollarwodbnice]

I honestly don't own a drill that could do this task nor do I want the responsibility of screwing up my head. Gonna call my machine shop that did the head and see if they can drill all the holes out for me...

Could someone explain how a 7 bolt head would end up on a 6 bolt block and also how the head bolts worked on it?

EDIT: I guess they didn't really work on it technically because it blew a head gasket.

 

[90moneypit]

Some people like the larger ports on a 7 bolt head so they put them on 6 bolts. Another possibility is someone wanted a 6 bolt bottom end in their 2g without the rest of the hassles. An easy way to check this is to compare the size and shape of the head in question with another 1g 6 bolt.

 

[IHeartMyHonda]

Some people like the larger ports on a 7 bolt head so they put them on 6 bolts. Another possibility is someone wanted a 6 bolt bottom end in their 2g without the rest of the hassles. An easy way to check this is to compare the size and shape of the head in question with another 1g 6 bolt.

7 bolts actually have smaller ports than 6 bolts. it helps with spool time and throttle response because there is less volume in the manifold and block to fill before air gets into the cylinders. thats why some people run them on their 6 bolt blocks.

 

[adollarwodbnice]

Well, no matter what the guy who did this decided to do it for he obviously didn't do it right... it really doesn't make much sense... for instance if the head bolts are already head bolts for a 6 bolt and they fit through the 7 bolt head you would think the same size 6 bolt studs would work too... they're REALLY close just not close enough. I'm starting to remember why I loved the 3/S so much... almost everything is interchangeable from heads to blocks to body parts... DSMs are a little more complicated.

Has anyone ever had a 7 bolt head drilled out to accept 6 bolt studs? Is there any sort of advantage that a 7 bolt head has over a 6 bolt... i've compared both the 7 and 6 bolt heads I have and I see no differences at all.

 

[BogusSVO]

the 6 bolt bottom has 12mm studs/bolts the 7bolt takes a 11mm bolt/stud
it is common pratice to ream out the 7bolt head to fit the 6bolt block

also you may want to do this oil mod before you install the head...
http://www.dsmtuners.com/forums/newbie-forum/341028-4g63t-head-oil-port-mod.html

now this is what you will want to have done so your head will fit down on the studs...
http://www.dsmtuners.com/forums/cylinder-head-short-block/341885-oil-port-mod-2-4g63t.html

 

[adollarwodbnice]

Thanks for the tip... don't think i'm gonna do that but if I get bad tick or odd pressure i'll consider it haha.

Just got the head back from the machine shop... hopefully I can get this sucker on finally!

 

[BogusSVO]

its your hla tic to deal with

what is the thickness of your head?

 

[adollarwodbnice]

If you mean the bolt holes they are now 12mm... I just got done torquing the head down and all just need to push my tensioner back in and set the timing and it's good to go!

This car should be alot of fun so hopefully I don't screw anything up... i've done several timing belts on a 3000gt and had no problems but i've never worked on a DSM before.

 

[BogusSVO]

the thickness of the head is measured from the valve cover rail to the head gasket surface

 

[FLASH1970]

Thanks for the tip... don't think i'm gonna do that but if I get bad tick or odd pressure i'll consider it haha.

Do it once and do it right. Listen to BogusSVO. I am DEFINITELY doing the oil port mod when I do the 2g head on a 6 bolt block. Also, Check to make sure your intake ports on the head match the manifold. You might have a 1g intake manifold on a 2g head which will rob you of power because the ports are shaped different.

 

[adollarwodbnice]

Do it once and do it right. Listen to BogusSVO. I am DEFINITELY doing the oil port mod when I do the 2g head on a 6 bolt block. Also, Check to make sure your intake ports on the head match the manifold. You might have a 1g intake manifold on a 2g head which will rob you of power because the ports are shaped different.

Technically I am doing it right... my friend has built several DSMs and had 0 issues without having to do any extra grinding on the head and assured me it's fine so i'm not worried about it. There's still many things to replace and double check before I can even start it so I have time to look over the whole car before cranking her over. Also, intake side of the head was ported and polished so that's been done for a while... I made sure gaskets and holes matched when I put the intake manifold on so there's no issues there.

 

[KazooGS-T]

Post a picture of the intake ports on your head, we'll know within two seconds if it's a 7bolt head or a 6bolt

 

[adollarwodbnice]

Sorry I guess I should update the first post... the car is all back together just finished putting everything back in just need to do timing belt and it's good to go.