7 bolt head 6 bolt block, head not seating correctly...

[ddavisaf]

Alright, I've been trying to get this cylinder head on all day and to no avail.
Here's what I'm facing. When I picked the block and the head up from the machine shop I had to have the block decked, and I shaved the head. Both are flat and within spec. ARP head studs, cylinder head bolt holes enlarged 1mm.
I'm having the worst time getting the cylinder head to mount flush on the block. It continually gets hung up on the guides on the block. I have measured the guides and the holes on the head for the guides. Both seem to be at 5/8" as I'm using a regular tape measure. I do not have access to a micrometer at this time.
My question is simply this. Do the guide holes on the head need to be enlarged to fit the guides on the 6 bolt block? Or have I just worked entirely to hard today to be rebuilding an engine?

 

[gsxtacy]

Man I was in your shoes (doing a 2g Head, 6bolt) about 2 months ago.

I put my 1998 (original) cylinder head on a freshly rebuilt 1991 6 bolt.

After having my cylinder head surfaced, I merely drilled the Head Bolt Holes from 11.1mm to 12.7mm (.50") and the head set down great on the dowels.

I put the studs in after setting the head down, less chance of nicking anything

You know 7 bolt 4g63 blocks have 11mm bolt holes vs. the 6 bolt 12mm bolt holes right?

Best of luck.


I hope it works out.

 

[jott5555]

the smaller hole diam on the 2g head is definetly the issue.. umm i want to say that apr offers a under cut head stud to help cure this issue.. honestly ide hate to drill my head out.. im not that good

 

[GVR4592]

It could be getting hung up on the metal shield that bolts to the block by the timing cover, or it could be a oval shaped dowel pin. Just throwing that out there, I've experienced both of those problems when doing head work. I've never put a 7 bolt head on a 6 bolt block so I don't know the specifics of that swap.

 

[ddavisaf]

So it's simply a case of being way to tired to be working on me car yesterday. Lets hope that today yields better results then. I decided against putting the metal shield back up for the time being also. Weight reduction or some other excuse.

 

[bryanwheat]

There are a couple of people that are giving the reasoning that the smaller holes are his problem, yet he already said that he drilled them!!!!!!! Read his post and you will see the he has already taken care of that.

 

[sbiggi]

The holes for the locating dowels are counter sunk. Are yours deep enought to except the entire dowel?

I have a 1g 7bolt head on a 6bolt block, and as far as I know they only enlarged the head stud holes, although they may have enlarged the counter sunk part to.

Mine dropped right on with out any issues.

-Seth

 

[1fast97gsx]

It sounds like 1 or both of your dowels got knocked slightly out of round of put in not deep enough or on a slight angle when they were removed for the block work. Once the headstud holes are enlarged it should slide right on.

You don't by chance have the cams installed leaving valves open that also currently have the piston at tdc in that cylinder right? That could also cause some "issues" when trying to put it on.

 

[ddavisaf]

The guides simply do not line up with the guide holes on the cylinder head.
I've spent at least like 10 hours on this stupid problem. I think the problem is the guide pin closest to the cam gears isn't matching the hole on the head. I looks to be off slightly. Drilling out the head bolt holes should have no affect what so ever on the guide holes.
Yes the cams are installed and set for tdc, along with the block. There is nothing obstructing the placement of the head other than that guide hole. So, in order to save money I've decided to file the guide pin down and I am going to try and drill the hole out a tiny tiny bit for the guide pin.

 

[ddavisaf]

There are a couple of people that are giving the reasoning that the smaller holes are his problem, yet he already said that he drilled them!!!!!!! Read his post and you will see the he has already taken care of that.

Thank you for pointing that out

 

[ddavisaf]

Problem fixed.

I had to shave about half of the left side of the guide pin down. If anyone else has to repeat this procedure, make sure you pad the block so you're not gouged the surface. Also, take the engine off tdc so as not to hit the piston. I did not have to round the pin, I simply filed down the left side to help the head slide on. It was trial and error. Shave a little, try again. Shave a little more, try again. Finally it fit.

 

[gsxtacy]

good to hear man

 

[jott5555]

the guide pins are there to make sure that the block is perfectally aligned with the block i just dosent seem slike a good idea to drill the hole's out and you have no clue if its strait or not then file it down to make it fit.. i donno i guess im a little to picky for that..

 

[GTM]

Problem fixed.
...
Also, take the engine off tdc so as not to hit the piston. I did not have to round the pin, I simply filed down the left side to help the head slide on.
...

I'm trying to figure out why people don't pull the cam followers, then there is no way to foul valves no matter where the pistons are. You can actually set the cam timing without them until you are finished stretching the belt.
................


I've run into this dowel pin problem a few times on other cars. I've pulled the pins and put them in the head. In some cases I've just barely set them in after grinding a better taper then let them self center/align with a dry run before properly seating them. If you are suspect this is the problem you can put masking tape on the head and then lower it down to make a mark on the tape for inspection.

Cheers,
GTM