1969 427 ZL1 Bolt Torque Specs

[Kenny M]

I'm in the process of building a original aluminum GM block and 074 Head engine. And I am in need of the proper Fastener torque specs. Most important are the Mains and Heads. If possible I would like specs for Bolts and Studs. Because I may use both. Also what do you guys like for Main bearing clearance with this Aluminum block? spinning 7800 RPMS.

Thanks you.

[jred]

wasn't that a special bolt???? I did one years ago and I think it had some sort of special bolt...

does the bolt have a neck down and a raised rib in the center of the bolt????

I think that if I remember correct that was a carr bolt and was to replaced as it was a 1 time use only...

I am talking rod bolts....
I think the mains were stock bolts with the stand off for the windage tray....

[GOSFAST]

I'm in the process of building a original aluminum GM block and 074 Head engine. And I am in need of the proper Fastener torque specs. Most important are the Mains and Heads. If possible I would like specs for Bolts and Studs. Because I may use both. Also what do you guys like for Main bearing clearance with this Aluminum block? spinning 7800 RPMS.

Thanks you.

Hi Ken, here's some numbers:

Mains=
studs- 100# (oil)
bolts (inner) - 100# (moly) / (outer) - 100# (moly)

Heads=
bolts- 70# (long) / 60# (short) (sealant on both)
studs- (7/16" fine) / 65# (long) / 55# (short) (oil on both)

If you are using aftermarket fasteners (ARP, etc) follow their directions, they will "override" what I show here?

Thanks, Gary in N.Y.

P.S. Strongly recommend "pinning" the front 4 lower main shells to the caps! We do all aluminum plaform builds this way for insurance!

[blykins]

On my all-aluminum FE engines, with a 2.750" main diameter, I will aim for .0018-.002" clearance "cold".

I've never pinned a main bearing, but I do green Loctite the cam bearings in.

[Kenny M]

Thank you guys!!