66 350 HP intake carburetor mounting studs

[Jeffrey B.]

I'm considering installing a 1/4 inch Phenolic carburetor spacer on my intake manifold to resolve a problem I occasionally experience with a hot no start problem. the issue I have is the studs that the carburetor fits over are too short to accept the lock washer and nuts when the spacer is installed. I would like to install longer studs however I can't get the studs that are in the manifold to back out and I'm assuming they are threaded into the manifold, not pressed into the manifold. I would like to know if I am correct in my assumption that the studs are threaded in before I go any further. The last thing I want to do is twist off a stud then have to deal with that problem. I tried two nuts tightened together then tried to back a stud out but the nut just turned and the stud did not budge.
Any feedback / suggestions would be greatly appreciated.
Thank You
Jeff

[Joe L.]

Re: 66 350 HP intake carburetor mounting studs

I'm considering installing a 1/4 inch Phenolic carburetor spacer on my intake manifold to resolve a problem I occasionally experience with a hot no start problem. the issue I have is the studs that the carburetor fits over are too short to accept the lock washer and nuts when the spacer is installed. I would like to install longer studs however I can't get the studs that are in the manifold to back out and I'm assuming they are threaded into the manifold, not pressed into the manifold. I would like to know if I am correct in my assumption that the studs are threaded in before I go any further. The last thing I want to do is twist off a stud then have to deal with that problem. I tried two nuts tightened together then tried to back a stud out but the nut just turned and the stud did not budge.
Any feedback / suggestions would be greatly appreciated.
Thank You
Jeff

Jeff-----

The carburetor mounting studs are threaded into the intake manifold. They can be a bear to remove.

[Jeffrey B.]

Re: 66 350 HP intake carburetor mounting studs

Joe,
Thank You for the reply. I have applied some PB Blaster to the studs and will let them soak until tomorrow, maybe that will help when I try to loosen them.

[Larry M.]

Re: 66 350 HP intake carburetor mounting studs

Joe,
Thank You for the reply. I have applied some PB Blaster to the studs and will let them soak until tomorrow, maybe that will help when I try to loosen them.

Kroil is a better product. Use it (or PB Blaster) repeatedly for a few days before trying again.

It is possible you could lose some of the aluminum manifold threads in the process of removal........so be sure you really want the spacer. But Helicoils can be used if the worst happens. Use anti-seize for re-assembly.

Larry

[Darryl D.]

[Jeffrey B.]

Re: 66 350 HP intake carburetor mounting studs

I put everything onto the manifold, spacer, gaskets, carb and air cleaner lose, then crumpled a ball of aluminum foil on top the the air cleaner and closed the hood. The ball of foil compressed and was still almost a full inch thick when I removed it.

[Richard G.]

Re: 66 350 HP intake carburetor mounting studs

Snap on, and others, make a stud removal tool. One is a clamp on style that toasts the threads when used. The other is like a threaded collet that tightens up onto the threads. A different size is required for every thread size. Lacking these tools or the willingness to trash your stud's threads I would use the two nut method with a couple of twists. First idea is to be sure, when attempting to back off the stud, to use the lower nut. This tends to tighten up the two nuts not loosen them, like it would if you used a socket on the top nut. Use a tubing wrench on the nut, if you can, as an open end wrench sometimes isn't enough to keep from rounding the nut. I like to use hardened nuts as these seem to have better thread tolerances don't round as easily. Second idea is the same two nut procedure but loctite the nuts to the stud. With the loctite the issue will be twisting the stud off not how well the nuts hold.

Try heating the manifold if you think you have reached the torque limit of the stud. Even if you pull the threads it's better than breaking off the stud in the head.

If it comes to drilling out the stud remember getting the pilot hole on center is the holly grail! Helicoils in aluminum are stronger than the original threads so don't worry about strength.
Best of luck.

Rick

[Frank D.]

Re: 66 350 HP intake carburetor mounting studs

I've never had the "two nut" method fail....
And please, spare me all the punch lines....

[Michael H.]

Re: 66 350 HP intake carburetor mounting studs

I would heat up the studs and then try the two nut method.

Mike

[Larry M.]

Re: 66 350 HP intake carburetor mounting studs

I would heat up the studs and then try the two nut method.

Mike

And I would first remove the manifold from the engine before the heating starts.

But I agree, some careful torch work and candle wax will remove the studs.........and likely without damage.

Larry

[Darryl D.]

Re: 66 350 HP intake carburetor mounting studs

"I put everything onto the manifold, spacer, gaskets, carb and air cleaner lose, then crumpled a ball of aluminum foil on top the the air cleaner and closed the hood. The ball of foil compressed and was still almost a full inch thick when I removed it."

Did you do your test with the foil in several spots on the air cleaner? Remember, these engines do not sit centered in the engine bay under the sloping hood.
Here is a link to the Corvette forum thread I spoke of that I started (I am 68hemi) asking the same question. See member Kingwoodvette's comment regarding his clearance test. I know there are slight differences in engine height due to aged mounts etc. but the difference in your test and his is substantial.

https://www.corvetteforum.com/forums/c1-and-c2-corvettes/4281624-thickest-phonolic-spacer-for-1965-350-365-engine.html

I am collecting parts to convert my 65 300 h.p. car to a 365 h.p. with factory type parts and would like to believe there is room for the spacer but so far it does not look good.

[Edward D.]

Re: 66 350 HP intake carburetor mounting studs

I'd like to add just a bit of advice to the 2 nut and heat methods. First, heat the manifold around the studs, not the studs, this will expand the aluminum. Second, when turning the studs don't simply pull a wrench (this is how you break them), you should strike the wrench with a light hammer sharply while lightly pulling. Your objective is to break the stud free, not twist and break it.

[Jeffrey B.]

Re: 66 350 HP intake carburetor mounting studs

I was able to remove the studs after soaking them in PB Blaster for 24 hours. They were still pretty tight. I used a small vice grip at the base of each stud and tapped one of them with a small hammer to coax it to break lose. I was not concerned about damaging them as I replaced them with longer studs to accommodate the 1/4 inch spacer under the carburetor. I placed a gasket on the intake, then the spacer with another gasket on top, then the carburetor, the air cleaner base and the air cleaner. Tightened the carb and again placed a good size crumpled piece of aluminum foil on top of the air cleaner and latched the hood. Still measures close to 1 inch clearance when I removed and measured the foil thickness. I started the car and gave it some revs with the hood down and latched and see no evidence of contact when I checked the underside of the hood. Hopefully I’m good to go. Thanks again for all of the feedback.
Jeff