Author Topic: 12mm block, drilled 11mm head-head stud questions (Read 4385 times)

Gearhead · « **on:** September 14, 2008, 11:00:43 am »

Ok, so.. I take the head off the 'ole Rabbit because it needs a HG. I get everything cleaned up, and go to button it up, and I notice that while the washers came out with the 12mm head bolts, there are still washers in the head... as in 2 washers per bolt. I go ahead and fight the lower "washers" out, set the head on the block and commence putting my new head bolts with new washers in the holes. The front ones drop down, but the washers on the back ones get hung on the cam caps. I look closely at the front ones and notice that the washers are LARGER than the recesses. After some searching here, I've come to the conclusion that I have a drilled 11mm head on a 12mm block.

Ok, I'm not much into rigging things, so I don't like the idea of ground down, double stacked washers, and I think I'd like head studs anyways. Does anybody know if the washers on 12mm studs will fit in the old 11mm recesses in my head?

Thanks.

blkboostedtruck · « **Reply #1 on:** September 14, 2008, 12:47:12 pm »

you could drill out the 11mm washers? but the double stack won't hurt anything!
Duane

Gearhead · « **Reply #2 on:** September 14, 2008, 12:57:47 pm »

Well, I have the washers that are already drilled, as is the head. I like to have as much of the "thread" buried in the block as possible, so I'd prefer to find out if the 12mm washers will fit into the 11mm recesses. I also don't care for the idea of the double stack. Unfortunately, I'm a bit of a perfectionist. Besides, the reason for the head being off is a blown HG. I don't want it to fail again because of any shortcut I take.

Gearhead · « **Reply #3 on:** September 16, 2008, 07:07:13 am »

Does anybody with a set of studs care to check the outer diameter of the washers? It would help tremendously.

Thanks.

dieseltim · « **Reply #4 on:** September 18, 2008, 09:51:39 am »

I just ran into this very same problem about 2 weeks ago. I have an 84 cy TD engine that I put rings and rod bearing in, and when I put on the head it just didn't seem to torque properly. After a few days of running, I blew a bypass hose and had to tow it home. Once the hose was replaced it was leaking at the head gasket. So, pulled the head off thinking that it was a blown head gasket because it got to hot from the blown hose.

Well when I got all the head bolts loose, I couldn't get them to pull out of the head. So, I lifted the head off with all the bolt still stuck in and used a hammer to knock them out from the bottom side.

I found that the washers were stuck in the head because the bore was too small for the washer and they had peeled off alum. as they were torqued down.

So, I borrowed a tool that is known as a piloted counter bore. It looks like a drill that cuts a flat bottom hole and has a guide to hold it straight.

It only took about .050 dia. of boring to get the hole opened up for the larger 12mm bolts to fall to the bottom of each of the holes and this time it torqued down just like it should.

I have driven the car almost 600mile since I replace the head and it seems to run great.

I would recommend removing the extra washers and reboring the holes like I did. After you do this you should have no more problems.

Good luck,
Dieseltim

Gearhead · « **Reply #5 on:** September 18, 2008, 10:45:20 am »

Where did you get the boring tool? Did you use it on a hand drill or a drill press? Want to borrow one for me? ha ha.

chrischris · « **Reply #6 on:** September 22, 2008, 10:12:55 pm »

When I used my 11mm head with my new 12mm block I took the washers to a machinist friend who put them on a lathe. He took them down a bit and they fit fine. I would first get a bunch of spare sized washers and find the size that you want your stud washers to be by trial and error. Then, once you find the right size, take that to a machinist to lathe it down.