1957 heads

[Theodore K.]

I am rebuilding a 1957 engine for my 57. This engine has the 539 heads. I noticed when I went to install the heads that the long head bolts (9) are the same rather than 4 of them (inside middle row ends) being shorter by 5/8". The various rebuild books list the 14 long (3-5/8") plus 4 mid length (3") bolts as being correct. Has anyone else noticed this for the 539 heads?
Thanks in advance for your reply

[Eric V.]

Re: 1957 heads

I am rebuilding a 1957 engine for my 57. This engine has the 539 heads. I noticed when I went to install the heads that the long head bolts (9) are the same rather than 4 of them (inside middle row ends) being shorter by 5/8". The various rebuild books list the 14 long (3-5/8") plus 4 mid length (3") bolts as being correct. Has anyone else noticed this for the 539 heads?
Thanks in advance for your reply

Theodore,
The early production small block V8s used the same (long) head bolts in all of the head bolt positions under the rocker cover, at least thru '57 production. I would have to do some research to determine when Chevrolet changed the four end bolt positions to require a mid-length bolt - it may have been as early as '58 production with the 770 and 772 heads. If memory serves, I think the head bolt length change was associated with a head casting change to improve oil drainback to the block valley. I hope this helps.
Eric V.

[Tom P.]

Re: 1957 heads

Seems as though the change was in 59.

[Joe L.]

Re: 1957 heads

Seems as though the change was in 59.

Tom, Eric, and Ted-----


Yes, I believe it was late 1959. I think the head bolt length change was coincident with the change from the "staggered" to "straight-across" valve cover bolt pattern.