When you click on links to various merchants on this site and make a purchase, this can result in this site earning a commission. Affiliate programs and affiliations include, but are not limited to, the eBay Partner Network.
I'm cleaning up the intake manifold on a small block 67 and reinstalling. What are the torques specs for the bolts? What is the proper sequence for torquing them? Do I need to put sealer on the bolts?
The torque specs for each bolt and the order you torque them in is in the 1967 Corvette Service manual. IIRC there are some bolts which go completely through the manifold into the oil flow portion of the heads and those should be coated with some Permatex Thread Sealer before installation. Those that do not make contact with any oil circulation via the heads do not need sealant. Hope this helps. C.J.
1. Don't know the torque specs.
2. The sequence is to incrementally tighten them in 2 or 3 passes. Starting in the center and moving in expanding circles to the ends.
3. Yes, they need sealer.
4. Consider blocking off the heat crossover passage. You can buy or make your own block offs. (Use stainless steel. Not cut up beer cans like we used to do.) Or, buy an intake manifold gasket that includes them. Look around, all the usual vendors sell such a gasket set.
5. You should remove the splash guard to clean under it.
6. If you did, make doubly sure that that it is reattached in such a way that the rivets or screws can't fall out. The old rivets may be too loose. I think you can still buy new rivets. Consider Lock Titing them. Or, tap the holes to take a screw. Lock Tite and stake them too.
7. Don't forget the crankcase ventilator can.
8. Look in the archives for a discussion on whether to use the intake gasket ends. Some people think a generous bead of sealant is better.
9. If you are installing an aluminum intake manifold, consider using washers under the mounting bolts. Otherwise the soft aluminum will get gouges. If you do use washers, consider using the smaller diameter AN washers (stainless, of course).
I'm cleaning up the intake manifold on a small block 67 and reinstalling. What are the torques specs for the bolts? What is the proper sequence for torquing them? Do I need to put sealer on the bolts?
Thanks!
Ben
You'll be OK on bolt torque if you tighten to 25 - 30 ft-lbs. As to sequence, imagine spiraling circles which start with the bolts nearest to the carburetor and work their way outward to the ends of the engine. Sealer, specifically Permatex #2 ,on all the bolt threads is needed.
Here is a picture out of the Chevrolet Chassis Service Manual with the bolt pattern torque sequence. Like Jim said, 30 foot pounds of torque for each bolt is correct. Good Luck with it. C.J.
IIRC, one or more bolts in the center area, if too long, will contact a pushrod. That will be a problem. Someone please confirm this for me. Dennis
That's correct. I don't have a car here to check it, but you can use a piece of coathanger wire in each of the (4) center bolt holes to identify the hole(s) where the correct length bolt is critical. The production intake bolts were 3/8"-16 x 1-1/8"; longer can hit a pushrod. Bolt length is measured from the underside of the bolt head to the end of the bolt, and production intake bolts didn't use separate washers.
As mentioned use Ultra black Permatex silicone. I use it around all ports and water passages as well as the end pads. The 4 corner bolts do not go into oil so sealant on them is not necessary. The other 8 are open to the inside of the engine and can leak oil, Ultra black on these as well. The second bolt from each end can hit push rods as well if it's too long. With a stock manifold I believe 1" is long enough nothing over 1 1/4". All silicone is not born equal use the Ultra black it's available everywhere.
From: Somewhere North of The 49th Parallel Ontario
If you really want to get the manifold install dead center in the valley, cut an old broom handle off and stick it in the distributor hole, and slip the manifold over it upon installation. Works like a dream every time.
If you really want to get the manifold install dead center in the valley, cut an old broom handle off and stick it in the distributor hole, and slip the manifold over it upon installation. Works like a dream every time.
Intake manifold install
Dennis
