C3 small block oil leak

[Joseph A.]

I am a new member and I just acquired a 73 small block. There is an oil leak pooling in one of the cavities of the intake manifold. It looks like it may be riding up one of the bolts. My plan is to take the manifold bolt out, coat the threads with permatex and torque the bolt back in. Is this correct? I want to then check the torque on each of the other bolts and note there is a GM factory torque sequence to be followed. What is that sequence and the lb/ft. Can you also recommend a quality torque wrench to me.
Thanks
Joe Asselmeier

[Joe L.]

Re: C3 small block oil leak

Joe-----

You've diagnosed the problem correctly and it's VERY, VERY common with Chevrolet V-8s. You must do as you surmise to correct it. However, you MUST make sure that the bolts and the bolt holes are completely and scrupulously clean before applying sealer and re-installing them.

The torque sequence is shown in the Chevrolet Service Manual and is also shown in more "generic" manuals like Chilton's. The torque values are shown there, too. I'm out-of-town right now so I can't confirm, but my recollection is that the torque on these bolts is about 30 lb/ft.

[Kurt B.]

Re: C3 small block oil leak

Joe Lucia , as always, is correct; the torque is 30 ft lbs for the intake manifold bolts according to my manuals. The correct sequence is to start with the bolts in the center of the manifold (the ones around the perimeter of the carburetor) and work outward in a clockwise spiral until all have been tightened to 30 ft lbs..
Kurt

[Michael M.]

Re: C3 small block oil leak

If you have an aluminum intake, I wouldn't fully torque them to 30 lbs. For a cast iron intake no problem but I have an aluminum intake and just snug my intake bolts because torquing them to full value will crack the intake near some of the bolt holes.

[John H.]

Re: C3 small block oil leak

Normal specified torque won't crack an aluminum intake unless there's some other problem (machining mismatch, warped casting, etc.); if you only "snug" the intake bolts, you're asking for problems with vacuum leaks, oil in the intake ports, coolant in the lifter valley, and all manner of other issues.