MikeT 90 C4sixer

I was wondering if there was a longer stud and nut available, for the inner thermostat housing bolt. The normal bolt holds down the EGR control solenoid, via a flat bracket. I think it is a poor design. If you had a longer stud, in place of the bolt, and nut it down, you could use another nut to hold the EGR solenoid. That way you do not need to loosen (or remove) the stock bolt that holds both down. The EGR solenoid needs to be moved to get to that inner runner bolt......
Just wondering, cuz my '88 F-body has a stud and nut for one of these bolts...

Joe C

if I'm understanding your post, try the stud/bolt used on the 85 L98 corvette. that bolt besides holding the thermostat housing, also secures a ground strap lug. can't see it not working for your application - about the only thing might be some clearance issues under the throttle body - ??? just a thought...

cohocarl

I don't know if this applies, but years ago when removing my 85's thermostat bolts, one was so corroded into the manifold that it snapped off. I tried getting the remains out, but messed up the threads in the manifold. Since I was removing the manifold anyways, I drilled a hole all the way through the manifold and J.B. Welded a S.S. bolt up through the bottom. Worked great!! I only did this because the threads in the manifold were messed up, but you should be able to put a stud in there.

WVZR-1

The earlier stud is 3/4" on either side of the hex. 3/8X16 for the threads but you should know that it seems. It was actually quite widely used for several applications and some dealers could actually still have some stock if you were interested in OE. The OE would be a 14091545 - you could get lucky maybe.

Joe C

I'm thinking we're on the same page here. seems like that part is still available. googled "GM 14091545," and several sources came up, with a variety of applications.

MikeT 90 C4sixer

Exactly what i was thinking, all good stuff here! So it appears that this bolt is a combination stud with a hex in the middle? Yea 3/8"-16 is very common thread....i have many of them bolts at work....use cap screws everyday. I could get one of them and cut it down.
Now my '88 IROC Camaro has the stud bolt, and no clearance issues...see pic. But for this C4, might have some issues with the EGR solenoid, namely the vac line that goes to it....i think it was directly over the housing bolt, and i was whining about that being in the way to get to the bolt. So i might have to make sure the new bolt is low as possible.
Just trying to see if this will work, if not, will go back to the original setup.Thanks all!

WVZR-1

Those bolts were never just basic cap screws at the water outlet and I'd think that a 3/8-16 with a flanged head would be the preferred at least on the side with the solenoid bracket. They would be very similar to an intake bolt with the flanged head. An older 3/8-16 GM converter bolt would be to short but the material and the head design would be just right.

MikeT 90 C4sixer

Copy that, i was just saying i could come up with something if need be. I will head to my local GM dealer tuesday, and see what i can get. I need several parts for my C4 regardless.

WVZR-1

It will be difficult to source 3/8-16 hardware from a dealer unless it's a very old dealer. You could use a 3/8-16 stud and then use a 3/8-16 flanged nut that would be likely easier to find at a quality hardware store.

MikeT 90 C4sixer

Well you were right, my local dealer did not have much at all for my C4. The good thing was the number mentioned above, was still a good number for the flange/stud, but it is discontinued. The only part i could get was a replacement AC Delco engine coolant sensor. They could get an EGR gasket, but they only sell them in paks of 10. I only need 1. Also needing the gaskets on the EGR pipe, both ends. Corvette Central did not have them.
I think i will try and come up with just a plain 3/8"-16 bolt, cut it down and get some nuts to hold things down. Shouldnt be too hard, and i can always go back to the stock bolts if i have to. But i will try the local auto parts stores as well. They do have an assortment of automotive style hardware.