Head bolt questions...

lyeinyoureye · Post by **lyeinyoureye** » Fri Feb 22, 2008 1:51 am

I coulda swore that I've read, either on this or the other forum, that not all 81 1.6s had 11mm head bolts, but I've searched for a good 15min and can't find anything. Were some 81 1.6s made with 12mm head bolts later in the year, or am I just making this stuff up as I go along?

Also, is the 11mm stretch bolt a better choice in order to avoid cracking the block since it's torqued to 55ft/lb+.5turn instead of the 66ft/lb of the non-stretch bolts.

Lastly, a fastener site sells head bolts with this description.

1.5 1471 cc 1971-79 SOHC DIESEL 12 mm bolts head bolt set

Are there really 12mm head bolts available for the 1.5s, and if so, could I use these on 11mm 1.6s?

Post by **Fatmobile** » Fri Feb 22, 2008 3:20 am

No, I tried to correct that guy but he didn't change it.

The 11mm headbolts don't go deep enough into the head.... that's why they crack the block or rip the threads out.
I went to the dealership for some parts and they had an '81 Rabbit diesel in the shop. Some guy bought a new head from the dealership and had them install it, they ripped the threads out of the block, tried to helicoil, haha, they ripped out too. $3500 later he towed his car home.... hell I could have sold him a rebuilt 12mm engine, installed for that.
v8volvo siad he's seen some '81s with 12mm headbolts.... I haven't.
I had an engine from a german made Rabbit, 1.5. Had the xzn headblots, the guy I got it from said it had 12mm headbolts because it was made in Germany. The engine hasn't died yet so I can't do an autopsy and see if he used gasser 11mm stretch bolts.

lyeinyoureye · Post by **lyeinyoureye** » Fri Feb 22, 2008 4:13 am

Has anyone ever tried getting longer 11mm head bolts from a fastener shop, or are they just not made and/or the holes in the block aren't deep enough?

Post by **Fatmobile** » Fri Feb 22, 2008 4:17 am

I just go with ARP head studs.
The gasser 11mm headstuds will fit the diesels and I find used ones on the vortex occasionally.
Just found a set for $50 shipped, posted it on the GTD forum and they are sold.

lyeinyoureye · Post by **lyeinyoureye** » Fri Feb 22, 2008 4:58 am

Do they have head studs for both the 11mm and 12mm or is it a one size fits all deal? They seem a bit pricey at ~$150, but at the same time, it'll probably be a wash wrt rebuilds, especially if I screw something up.

82vdub · Post by **82vdub** » Fri Feb 22, 2008 9:07 am

lyeinyoureye wrote:Do they have head studs for both the 11mm and 12mm or is it a one size fits all deal?

11mm=12mm? No, for proper fitment, 11mm bolts should be used where 11mm bolts are supposed to be installed and same for 12mm.

ARP doesn't list head bolts or studs for the VW diesel engines. However, I would suggest calling their tech department and see if they offer them (not in the catalog), or if they can make them.

vwkook · Post by **vwkook** » Fri Feb 22, 2008 9:27 am

How long are these studs? Does anyone have a picture or a link to a picture?

VWCaddy · Post by **VWCaddy** » Fri Feb 22, 2008 10:51 am

No info on the ARP studs for the VW diesel, but here are some pictures of the Raceware studs I put in my '82/1.9D:

nicknack2 · Post by **nicknack2** » Fri Feb 22, 2008 12:27 pm

VWCADDY

so you retreaded the block and made the holes bigger in the head... can yoy explain to us the process of what you did???

VW Jon · Post by **VW Jon** » Fri Feb 22, 2008 12:33 pm

I've got several early 1.6 engines as well as a few 1.5s, and none of them have the problems with the blocks cracked or other problems with the threads.

I think some of the problem with broken out blocks may be the fact that few people completely blow out the oil and debris at the bottom of the holes, and the pressure when reinstalling the headbolts cracks the block. I've noticed on the 12mm 1.6s that the counterbore at the top of the threads is usually bigger, which may help by allowing excess oil at the bottom of the holes to wick up when tightening, thus preventing a hydro lock condition.

lyeinyoureye · Post by **lyeinyoureye** » Fri Feb 22, 2008 12:38 pm

Does anyone have any measurements on stud length and possibly the threads per inch on an 11mm block?

82vdub · Post by **82vdub** » Fri Feb 22, 2008 12:48 pm

The under the head to tip of the bolt (not end to end) distance should be approximately:

11mm - 4"
12mm - 4.5"

Oops! After I posted this, you were wanting head stud lengths. The above info is for the head bolts, not head studs.

VWCaddy · Post by **VWCaddy** » Fri Feb 22, 2008 1:57 pm

nicknack2 wrote:VWCADDY

so you retreaded the block and made the holes bigger in the head... can yoy explain to us the process of what you did???

No, simply used the tap to chase the threads in the block to ensure they were clean to allow for full insertion of the studs. I did the swap with the head in place, so had to rig up an extension with a ratchet to allow the tap to run down to the bottom of the bolt holes.

tawney · Post by **tawney** » Fri Feb 22, 2008 5:49 pm

Does anyone have any measurements on stud length and possibly the threads per inch on an 11mm block?

Thread size for the 11mm is 1.5mm; for the 12mm it is 1.75mm. I don't have the studs, but the 11mm bolts are 94mm from washer to tip; 12mm bolts are 112mm

nicknack2 · Post by **nicknack2** » Fri Feb 22, 2008 7:11 pm

VWCADDY Wrote:

No, simply used the tap to chase the threads in the block to ensure they were clean to allow for full insertion of the studs. I did the swap with the head in place, so had to rig up an extension with a ratchet to allow the tap to run down to the bottom of the bolt holes

no head gasket was replaced???