does anyone know ftlbs to torque down aluminum intake to a set of aluminum AFR heads ?

 

my edelbrock unit was 11ft lbs max GM Crate motor ZZ383 heads are Aluminum “Fast Burn” cylinder heads.

from the manual.

Intake manifold bolt (sequenced). Re-torque bolt after running engine for 10 hours.
First pass ........................................ ................... 97 in.lbs. / 11 Nm (Teflon pipe sealant)
Final pass ........................................ .................. 11 ft.lbs. / 15 Nm

 

Well its been two hrs since the question. An old Chilton Manual states:
30 for iron
25 for the soft stuff.

 

I would check with AFR, they should have recommended torque specs. It is their head that the threads are located in, they should have a spec. Good question!!!

 

Ive done serches on line for my heads and AFR torque specs are always coming up

 

some aluminum heads have steel helicoil inserts or similar, (some not), different alum alloys / heat treat. Factors which can affect optimal torque ratings.

Suggest best to get torque specs for Your specific head part number direct from head manufacturer

 

This may help

https://static.summitracing.com/glob...s/afr-1054.pdf

https://www.airflowresearch.com/sbc-...-instructions/

 

If they are 3/8-16 bolts, I cannot imagine them having "inch-pound" torque requirements. Those bolts get 28-32 foot-pounds torque with iron heads. Aluminum intake will require lower torque...but not THAT low. The 1971 CCSM specifies 30 ft-lbs for intake manifolds...whether iron or aluminum. I think 25 ft-lbs would be about right for an AL intake on iron block.

 

I am going to stick my neck out and say that I have never torqued an intake to a head in my life.
I go around in the pattern at least three times.....each time the gasket will compress slightly and the adjacent bolt will be loose again. When you run the pattern and the adjacent bolts do not feel loose, you are close.
From there.....one can feel that the fastener is tight, it simply will not move any further without applying excessive force on it. Another issue is how are you going to torque the four center bolts on a single plane intake? No way to get a torque wrench in there.....you have to go by feel. Now when I say by feel.......that does not mean tightening the **** out of it......if you do it right, and have a good perception of how the bolt feels as you tighten it, you will know when to stop. The orginal first series Torker intake was so tight in there that I have an offset box end wrench that is ground thin on the outside edge just for this purpose.
Paper gaskets do not crush much but the Fel-Pro blue steel core laminate gaskets (like the 1204, which is the most common gasket I use, I keep a pair on the wall) will crush about .050 before compressed fully.
If you work around a lot of aluminum engine parts like I do (bike engines).......you adapt to having soft touch with fasteners.....
Neck stuck out now......carry on

Jebby

 

The only reason to use lower torque on an aluminum intake is that the aluminum 'boss' under the [steel] bolt can only take so much compressive load before the boss gives way. The bolt would still prefer to be torqued to 30 ft-lbs, so that it gets the proper amount of stretch in it. But, that would get close to the compressive strength of of aluminum....not so good.

 

I'm with Jebby. That's how I have always done it and never had an issue. Other things torque readings are more an issue, heads, main caps and rod.bolts yes but stretch on an intake bolt? Come on you shouldn't be near stretching a bolt.

 

Youre responding to posts that have been unanswered for 4.5 years.