The Stovebolt Site Forums The Shop Area Engine Shop Carb > Intake manifold studs?

After adding a carb spacer and deflector for better carb cooling I now notice that the mounting studs (to the intake manifold) are a tad too short.
Before I order some hardware, can someone please tell me what the actual size of those studs are?
I can then source out something that is a tad longer than stock.

1955 1st series w/1957 235 inline 6

5/16-18 on the end that screws into the intake and 5/16-24 on the end the nut screws on. Pull an old stud out and take it with you to compare.

If the studs come out, any 5/16-18 bolt the correct length will work, also, any decent auto parts or hardware store will have studs. All-thread cut to the correct length will works to. Be sure to use the same thread pitch nuts.

Hey thanks, guys

The idea of using all-thread/ready-rod in a pinch is good -- but that might not have the tensile strength when it comes to heat (?)

Providing I can get them out , what do you suggest using on the threads when screwing back into the manifold?

Double nut the studs, if hard to remove, warm up the engine first, add Kano or similar oil before it cools. Locktite or similar upon reinsertion.

Ed

Thanks, Ed -- you kinda confirmed what I was thinking

all thread works really fine for this, they won't see anywhere near enough heat or tensile stress to be a factor. I would also use never seez to put them back together. But that is just me, I know one day I will probably want to take it apart. I have spent 35 years in industrial maintenance, I spend a lot, a lot of effort assuring I can get my stuff back apart. I know it won't last forever.

As well as all-thread (or ready-rod) I also have some long 5/16-18 grade 5 bolts laying around. Using the appropriate sized cutting die I can try extending the threads further and use coarse locking nuts to hold the carb down.
Alternatively, new 24 pitch threads may be cut above the existing 18 pitch (manifold) threads and use the existing carb nuts. This will mimic the OEM studs, albeit longer.
Of course all this depends on whether the cutting die will actually cut into the grade 5 bolt. If not, then it's either ready-rod or a trip to FLAPS for longer studs.

But first I have to get those &*%$ing existing studs removed

So far, I've tried heating the surrounding (intake) cast with a heat gun and applying Liquid Wrench and letting it sit for a couple hours ...No Joy.
I'm tapping the head of the stud with a small hammer, and using the 2-nut method of gripping the stud. But find that the bottom nut just wants to unwind with the top nut when under a good amount of torque.

I've also discovered a vintage 1/2" drive Grey brand cam-style stud extractor in my stash.
So after reheating the cast then followed by an equal mix of ATF, acetone and paint thinner and leaving that soaking for a couple days, I thought I'd give the extractor a try.
The suspicion is that the extractor may mash up the lower part of the stud, but it's being replaced any way. A greater concern is snapping off the stud

To lower the risk, shall I also use an air impact wrench (tuned to 'low') on that extractor?

I do not have a stovebolt intake to inspect, so the following are general statements:

Years ago, we used to restore and sell lots of multiple carb set-ups.

Many of the manifolds had open holes for the carburetor studs. Using all-thread here would NOT work, as it would be impossible to tighten the studs to the manifold.

As mentioned above, the better FLAPS will have a stud assortment. Generally, the studs will have threads on both ends, with a non-threaded section in the center. This non-threaded section makes it possible to tighten the studs to the manifold, and if an open hole, will prevent the stud from extending into the manifold plenum. Dorman Products is one manufacturer (there are others) that has an excellent selection of studs.

The studs come in a number of diameters and threads. GENERALLY, GM used a course thread into the manifold, with a fine thread for the retaining nuts. If one is changing studs, one could also change the fine thread to course (ie all-thread), but I have always believed that engineers have a reason for their actions, and have tried to duplicate their work.

As mentioned above, double nut the studs for the purposes of either removal or insertion.

Jon.

I too don't know if stud holes are bottomless. I guess we'll find out
But first, I have to get the darn things out of the manifold -- without snapping them.
And as mentioned earlier, the double nut procedure does not appear to be working (after tightly jamming them together they are still climbing back out).

Heat the manifold, not the stud, to red hot, wait till it cools, heat again, then try and back out. Heat gun will not be hot enough!

Ok, got the studs out. Propane torch with a turbo option was just enough to heat it up. I also took some other advice and used some candle wax on the stud while it was still hot.
Seemed to do the trick as the studs came right out using the double-nut method.

Also, (for custom making of new longer studs) when I tried to die cut some threads in the spare bolts I have, seems they are 3/8" not 5/16" ..at least that's what the die stamp reads -- diameter measured at .354"
So it now seems, manifold: 3/8-16, carb: 3/8-24.
After applying some no-seize compound, I'm ready for reassembly.

Thanks again for your help

Tell us about this candle wax trick. Do you pour it over the hot stud so that it wicks down into the manifold in the threads? I'm intrigued.

Found out about the wax trick somewhere on other forums. I used a propane torch to heat up the cast surrounding the stud, let it cool for a minute then rubbed a wax candle onto the stud and let it drool down. Of course it fizzed away for a bit. Then using the double nuts I simply unwound the stud out of the manifold. And yes, I think it migrates into the threads once the dissimilar metals are released from one another due to the heating process.

Excellent! Thanks.