Author Topic: identifying head bolts (Read 3923 times)

veeman · « **on:** April 06, 2005, 01:49:24 pm »

I did some searching of the archives, but didn't find an exact answer about this...

Can you identify the head bolts by looking at the bolt's head? In other words, do all 11mm bolts have the normal hex head and all 12mm bolts have the 12 point head?

I have an '81 CR engine and it seems they changed styles midway through the year.

Thanks in advance!

lord_verminaard · « **Reply #1 on:** April 06, 2005, 04:50:13 pm »

Well, according to ETKA, I have the CR engine up to chassis number 176 338 using 11mm hex head bolts, and 176 339 and later CR's using 12mm triple square. The only other 11mm bolts were used on gassers and had polygon heads. They were also something like two threads shorter. :?:

Hope this helps.

Brendan
84 Scirocco 8v
00 Camaro L36 M49

janb · « **Reply #2 on:** April 06, 2005, 06:15:03 pm »

I have 11mm diesels with both styles. But... the factory issue diesel was hex, and non-stretch

all '81'D's (CR) that I've run across have been 11mm

The counter sink (spotface) is smaller dia but deeper on 11MM
11mm blocks have 16D cast into back; 12mm = 1.6D in casting

janb

veeman · « **Reply #3 on:** April 07, 2005, 06:20:24 am »

>>11mm blocks have 16D cast into back; 12mm = 1.6D in casting

So the only difference in the casting marking was the decimal point? Interesting.

chrissev · « **Reply #4 on:** April 07, 2005, 08:31:55 am »

Quote from: "Sharkey"

One of the tricks people tried to keep 1.5D's from blowing head gaskets was to use 11mm gas stretch head bolts on them. It didn't help, but they do have the triple square heads, making things more confusing yet.

ah, the 1.5 diesel. Had two of them. Blew the head gasket on both within 6 months of buying them.