Is it possible to tell 11mm from 12mm head ... if not off engine ?????

[doonboggle]

Not yet.  That comes after the proper tool to extract one is delivered so that it can be determined to be a 11 or 12mm version.
The recess or non-recess I don't believe has been focused on.  In my case, I just want to know what version of bolt I have.

so after all this have we confirmed that 11mm sit above the head surface where as 12mm are recessed in to it? all 11mm and 12mm? or only select few?

[8v-of-fury]

same here bro. i just blew a hg.. need to pull the head as well. and order new bolts

[RustyCaddy]

better brains than mine have already commented on this but to me at least one of these bolts looks to have six sides like a hex head???

the hex heads on 11 mm headbolts use a 10 mm allen style bit.

373 F heads can be either 11 or 12 mm apparently (so as to maximize confusion).

i picked up a 10 mm allen head socket at Sears for a 11 mm headbolt and a triple square (for a 12 mm bolt on a different head) and both held up really well...Autozone also sells triple squares but they are really soft.  Sears steel is better (made in USA!)

[doonboggle]

Am presently waiting on delivery of the 8- piece (http://www.restockit.com/8-piece-xzn-set-%28vimxzn100%29.html) kit ordered last nite. 

Searched for hours and this one seemed to be the best offer, with qood quality, I could find.

 Did not want all 8 ... but by the time that the 2 I wanted were ordered, and having to pay shipping, would be right at their price almost ... so decilded to go for the whole kitten kaboodle. 

Plus, along with free shipping, they also offered an additionsl 5% discount ... and no, I do not own any of their stock ... just posting the order info.

same here bro. i just blew a hg.. need to pull the head as well. and order new bolts

[doonboggle]

If you're chatting about my image, they have the 12-point heads.  This was the focus the last couple of days trying to determine the proper removal tool. 
TORX was not recommended; I had one also that I initially commented on; and was considering getting the 12-point version of TORX. 

Fellows here more knowledgeable than I suggested no go to using it.

better brains than mine have already commented on this but to me at least one of these bolts looks to have six sides like a hex head???

the hex heads on 11 mm headbolts use a 10 mm allen style bit.

373 F heads can be either 11 or 12 mm apparently (so as to maximize confusion).

i picked up a 10 mm allen head socket at Sears for a 11 mm headbolt and a triple square (for a 12 mm bolt on a different head) and both held up really well...Autozone also sells triple squares but they are really soft.  Sears steel is better (made in USA!)

[williamtaygan]

I've got a 373F head right here with 12mm holes, and a 373B with 11mm holes AND a 373B with 12mm holes.  Also got another 373F and a 373M ALL 1.6L mechanical heads, but don't have them pulled.  Both the 373B (11mm one) and the 373F (12mm) have recesses for the washers, I've heard the 11mm washers are smaller(?)

If I had to guess I'd say you've got the 12mm head.

better brains than mine have already commented on this but to me at least one of these bolts looks to have six sides like a hex head???

the hex heads on 11 mm headbolts use a 10 mm allen style bit.

373 F heads can be either 11 or 12 mm apparently (so as to maximize confusion).

i picked up a 10 mm allen head socket at Sears for a 11 mm headbolt and a triple square (for a 12 mm bolt on a different head) and both held up really well...Autozone also sells triple squares but they are really soft.  Sears steel is better (made in USA!)

[RustyCaddy]

Okay...what would be the #3 bolt in the headbolt tightening sequence looked like a hex head to me.

a friend had a 373 F...i told him it had to be a 12 mm like the Brazilian i have but he corrected me saying it was an 11mm...so go figure.

was the TORX SAE because i don't think that would work like a metric triple square...never had a problem with mine anyways

[theman53]

The casting # and letter on the head means pretty much nothing when it comes to finding out the bolt size and mech or hydro. About 2 years ago we were going to put a table together for the faq and came out with that. Nothing is concrete on what casting # is what. I believe all it can tell you is if the head originally had turbo vavles or not...but I am not certain on that either as it has been a few years now.

[Mark(The Miser)UK]

Okay...what would be the #3 bolt in the headbolt tightening sequence looked like a hex head to me.

a friend had a 373 F...i told him it had to be a 12 mm like the Brazilian i have but he corrected me saying it was an 11mm...so go figure.

was the TORX SAE because i don't think that would work like a metric triple square...never had a problem with mine anyways

I agree, does look rather 'hexy' to me too
How about a fingerprint of all the bolts [take a white sheet of paper and stuff thumb onto bolts with paper in between ]