Nice and snug with a 9/16 wrench . Thats the spec Ive allways used with no problems

 

Same as factory 25-30 ft pounds. Use a hardened washer between underside of bolt and aluminum intake. Neither washer or bolt should be plated either plain or stainless steel. Zinc and galvanize are reactive with aluminum when wetted.

Some intake fastener holes of the head are closed while some are open to either places with coolant or oil. Fasteners going into blind holes only need thread lube which is engine oil in slipperiness, this has an effect on torque readings so super lubes are not recommended. All threads should be chased to insure they are clean snd straight. Threads open to coolant or oil must be sealed, in this case a thin coating of Permatex Aviation Gasket Maker #3 is my recommendation as it firstly offers thread lubrication similar to 30wt oil which is what the OEM’s base their torque numbers on and secondly it is a pliable non hardening sealer that well insures that coolant nor oil will pass up the threads.

Unless your using an air-gap intake you will find that unless your living in a very cold climate that aluminum intakes do not need exhaust heat, so choose an intake gasket that seals off the exhaust crossover passages if that suits your operating climate.

You will also find that carburetors on aluminum intakes acquire enough heat transfer from the manifold that modern fuels formulated now for nearly 50 years to support the needs of high pressure fuel injection tend to boil off in carb float bowls so I recommend at least a 1/2 inch thick insulating spacer between the carb and the intake. The Edelbrock carb is particularly sensitive to this but not necessarily alone though the Rochester and the Holley are usually less troubled.

Bogie

 

Long ago I mounted a aluminum intake manifold to a 1969 Ford 429 and a 4 barrel Holley, the fuel literally boiled out of the vent tubes. I then installed a spacer kit of that time period of 4 thin aluminum spacers and 6 thick gaskets between each plate, it worked great.

 

which heads? 1995 and older, or 1996 and newer vortec heads?

the 1996 and newer use eight 5/16" bolts (18 ft-lb) , the older heads have twelve 3/8" bolts (25 ft-lb)

 

Also check the length of the bolts that go into the blind holes in the head. My Edelbrock flange was a little thinner than the old iron intake, and some bolts tightened up in the blind hole before they actually pulled the intake down fully. Initially a little antifreeze seeping, and then a streaming leak. Needed to use 1/4” shorter bolts, or more washers under the bolt head.

 

always used a wrench to hand tighten on gen 1 chevy small blocks and big blocks

 

And retighten after 100mi or so

 

It all depends what model your using?

 

Pretty sure my instructions said 35 ft/lbs as I just got it on last week. I got them to at least that and never heard my ~20yr old craftsman torque wrench click. After I tested the torque wrench on a larger bolt in a vise and still couldn’t make it click. I may have overtightened but I doubt it was enough to stretch the bolts and I didn’t have any pull out.

 

Click style torque wrenches will take a set if you leave them turned in. Most fail

 

I had it set to 0 in its case in the bottom of my toolbox, but I had not tried to use it in years.

 

I've never torqued an intake manifold on a SBC iir BBC in my life. Just a good snug tightening always worked on aluminum or cast iron for over 50 years.