Technical What grade of bolt is needed for a small block chevy intake?

Just installing an aluminum intake on a 327 small block chevy. I wanted to know the torque spec and what grade of bolt should I use? Thanks Jay

 

Minimum of grade 5.
Some thread sealant on the threads and a dab of anti seize at the shoulder.

 

Grade 5 is fine for the intake, install washers under the bolt heads to get a better torque & to avoid tearing up the manifold. 30-35 lbs. of torque is fine & put a light coat of silicone on the gasket around the water passages on the heads if the intake gaskets you are using does not have sealer built into it.

 

Chevy shop manual has sequence to follow also. But who ever does that.

 

Thanks for the info! Sealer is built (made) into the gaskets Fedlpro 1204s so i guess I don't have to add "The Right Stuff to the gaskets. Glad that grade 5 are good enough. Got lots of those and washers. Someone told me before to use grade 8 whey so high?

Jay

 

All it has to do is seal not hold a rotating mass from exiting out the side of the block.

 

At 35 lbs torque, grade 5 is more than adequate. Grade 8? Why? Not a shear problem, no friction cutting into the shank by an aluminum manifold.

 

If 5 is good 8 MUST be better, just another stupid idea. Actually 5 is a bit of overkill, as they just keep the manifold sealed, but they would be my choice, new of course.

 

Toss the rubber end seals out and use The Right Stuff instead. It will seal better and fill irregularities that the rubber won't. I haven't used end seals since I discovered The Right Stuff.

I would still put some sealant around the water passages, and torque the bolts according to this sequence:



Do it in 3 steps.........first at 15 pounds, then 25 pounds, and finally 35 pounds.

Don

 

After a few heat cycles re torque the bolts. I always do.

 

Seal the bolts. The seal on the gasket does not seal the bolt holes which can go into the the water jacket. I add sealer around the water passage openings as well. Just redid one of those because the bolts had leaked.

 

x2 on using right stuff & leaving out the end gaskets. Solves possible fitment issues if some of the iron has been milled.

 

X2 on sealer for bolt threads some go to water some go to oil. Ever see a SBC with oil around the center 2 intake bolts on each side and wonder where it came from?

 

So does everybody else weld a socket to a short 9/16 box end to torque the 4 center bolts? curious what other guys do

 

Dial indicator elbow

 

Yep, A grade 5, 3/8-16 bolt has a proof load of 6600 psi and a tensile strength of 9300 Psi. A grade 2 is 4250 PL and a 5750 TS.

I'm sure a grade 2 will hold your intake on and not leak.

I have used stainless fasteners in non- critical areas for many years and enjoy the benefits of reduced corrosion.

BTW these are generally slightly stronger than a grade 2.
I don't buy grade 2 either, but just wanted to point out that in this application you could almost use wooden dowels to hold the intake in place.

Many years ago, when I was student teaching, I had two students lift an engine by the carburetor studs with NO BOLTS holding the intake. The
intake had been installed with the old hardening Permatex. #2?

 

Thanks for all the great advice guys! The Right stuff thing is the best. I will also coat the threads of the bolts for a better seal. The HAMB is the best.
Jay