Thread Size for EA82 Head Bolts

Bryan1 · Post by **Bryan1** » Tue Oct 18, 2011 7:28 pm

G'day Guy's,
The reason I'm asking the above question as in none of the documentation I have here including a hard copy of the service manual does it state the thread size. When my father in law redid the head gasket on my L series I only just found out the threads were stripped and he heli coiled them. My guess is he could of gotten the wrong pitch as he did say when they were torquing up the bolts they did seem to have some resistance. Now the head gasket only lasted about 2 months and he did say head itself was in good condition. So this the reason I had so much fun with that motor.

If any guy's do know what the thread size it would appreciated to let me know as this will solve my problems with that EA82 motor.

Regards Bryan

revmax · Post by **revmax** » Tue Oct 18, 2011 8:01 pm

they are american thread 7/16 UNF

steptoe · Post by **steptoe** » Tue Oct 18, 2011 10:03 pm

Really ? EA81's use M11 (pitch i dunno) thought EA82 were same - wonder if UNF 7/16 is same??

revmax · Post by **revmax** » Wed Oct 19, 2011 5:10 am

I measured the thread as imperial,7/16 x 20 if it were metric it would be M11x 1.25 and there is no such thing so it has to be UNF.

steptoe · Post by **steptoe** » Wed Oct 19, 2011 10:51 am

revmax wrote:M11x 1.25 and there is no such thing so it has to be UNF.

Like a red rag to a bull

steptoe · Post by **steptoe** » Wed Oct 19, 2011 10:52 am

tada,aa,aa

http://buy1.snapon.com/catalog/item.asp ... up_ID=1163

FROG · Post by **FROG** » Wed Oct 19, 2011 11:05 am

my parts book says M11 also

Bryan1 · Post by **Bryan1** » Wed Oct 19, 2011 11:37 am

Hi Guy's,
First thanks for the info on the thread size. Now 7/16" is 11.11mm and 20 tpi works out to 1.27mm pitch. So using a thread guage and verniers yes one would think they are UNF. It doesn't surprise me in the least they used M11 which is a non standard thread however, it is an ISO thread.
After speaking with my father in law they did heli coil the stripped threads with M10 x 1.25 pitch and they used the original bolts so that was the reason why they said they were tight to do up. I am surprised the head gasket lasted so long and the compression test results are now real clear as what happened. We scored a free Hyundai Charade '92 model 5 door hatch the other day so my first job is taking the head off that and checking it out. Once that car is going I'll get the subi in my shed and take the head off and redo the job properly. I'm working on cleaning up my shed and now I have enough room to get the charade in and my main work bench and 3x2' surface table clear, checking the flatness of heads will be a breeze. Also I do have a smaller surface plate so hopefully it is small enough for checking the block too.

Regards Bryan

steptoe · Post by **steptoe** » Wed Oct 19, 2011 12:26 pm

I give revmax credit for finding a close fit imperial

Bryan1 · Post by **Bryan1** » Wed Oct 26, 2011 5:06 pm

G'day Guy's,
Well got to work on the subi today and got the head off and found it wasn't tight so no wonder it leaked. I am surprised it lasted so long too. Anyway the head gasket is in as new nic so I'll re use it and put some Hylarmar on to ensure it seals.

Now all but 2 thread holes were stripped so they were heli coiled M10x1.25 so now I'm chasing some M10 head bolts.

What I need is

130 long 4 off
115 long 2 off
105 long 1 off

All M10 x 1.25 pitch.

So you any of you guys know of any other models etc that would use the above bolts as it would be great if I could just go to a wrecker and know what motors used them.

Regards Bryan

revmax · Post by **revmax** » Wed Oct 26, 2011 6:06 pm

the crank case bolts on EA81 and 82 are M10 x 1.25 and I happen to have a crap load of them from motors I have stripped.
I'll have a scrounge for ya.
BUT I think helicoiling the holes out to the corect size would be better.

steptoe · Post by **steptoe** » Wed Oct 26, 2011 9:55 pm

might be a bit tricky to do after repaired to M10. Can you get m10 1.25 threaded rod in stainless and make some studs if no bolts available ?

I would not re use a head gasket on one of these

revmax · Post by **revmax** » Thu Oct 27, 2011 5:34 am

steptoe wrote:might be a bit tricky to do after repaired to M10

not at all the pitch is the same just the diameter is bigger.

steptoe wrote: Can you get m10 1.25 threaded rod in stainless and make some studs if no bolts available ?

Stainless has not got the same tensile strength as Hi tensile carbon steel bolts and will stretch.

Bryan1 · Post by **Bryan1** » Mon Oct 31, 2011 6:56 am

G'day Guy's,
Anyway ended up getting some M10 x 1.25mm Graded 8.8 bolts and used them, I had to run a die down on some to make the bolt thread the right length. Got the motor all back together and she kicked into life pretty well straight away.

No more coolant leaks and the motor is running sweet now although still have the dreaded back firing on de-acceleration. All in all I'm pretty happy with the rebuild and the subi did serve serve well yesterday taking all the plants to the local show.

Regards Bryan

steptoe · Post by **steptoe** » Mon Oct 31, 2011 7:09 am

Great stuff and thanks for finishing the thread