Soon assembling a BB engine, and will be running .060 head gaskets. What is the formula for figuring the intake manifold gasket thickness using these head gaskets?

Torque the heads down several times and then use a feeler gauge to measure each corner, top and bottom, of the manifold to head clearances with no gasket and go from there

IIRC, for every .010" increase or decrease of the head (or block) surface you will need to either increase or decrease the intake manifold side of the head .012";. in your case you would be adding .040" of height on the head to block surface (assuming block hasn't been decked) vs a stock .020" shim head gasket. so theoretically you'll need to add something between .045"-.050" on the intake surface. truth is there's no substitute for mocking the parts up and physically measuring what you need. i use old intake gasket (big block wedge) that i've cut the intake/head flange off of to use for mock-up and the paper gaskets can also help in constucting what you need.

Set your intake on the motor withthe valley pan intake gasket in place and look at the bolt holes on the intake manifold and see if they are aligned and centered over the holes in the heads
If so your good, if not you will either need to have the intake cut enough to get te holes aligned or add gaskets to get it in the proper place to make it fit properly
Good on you for taking the time and efforts to get it right

Thanks for the responses! It’s a blower intake, no valley pan gasket. I’ll just have to do some measuring, was just wondering about any formula to figure out to order intake gaskets now.

as the blower intake does not use a valley pan tin, i would do this.
set the intake on the engine in question.
shim the intake, using the china walls until the bolt holes line up to your satisfaction.
measure the thickness between the intake and cylinder head, using feeler gauges of the stack necessary, add some amount for crush, then select your intake gaskets.
seal the china walls with the appropriate rtv.
just my opinion on how i would solve this problem.
your mileage will vary.

I've always used a stock valley pan to keep hot oil off of the bottom of the intakes, no matter which intake, blowers or others.
I cut the outer edges off with tin snips and seal the pan to the block and intake manifold with a good grade of adhesive silicone
Same thing on the intake gaskets, seal them to either the heads on intake manifold, not both
Good luck on your deal
What type of blower and HP are you using and shooting for?
BTW, I learned a long time ago you can never have to many parts for our car racing hobby: devil:
I would order two sets of every thickness intake gasket you can buy and use them to set your intake up on the motor, don't forget the valley pan with an oil drain back hole drill in the middle of that pan for oil drain back

Dyers 6-71 on a +.030 413. COMP Cams 21-228-4, .545/.545 lift, 285 int./297 exh duration, 110 centerline. Under driven, 38 tooth on top, 34 on crank., 10.5%. Maybe 6lb boost. Not sure on HP numbers, street car.