Heat Stove Screw Size

[cericd]

Anyone know the correct size of the heat stove screws? I'm missing the two that hold connect the stove pipe to the heat stove, also missing one of the top heat stove screws. Are the ones that connect the pipe to the stove the same size as the others along the top of the stove?

Also, do they reproduce the two heat stove pieces or will I need to restore my originals? I know the pipe should be black but what finish would the stove have had? I assume most finishes will burn off due to the proximity to the exhaust manifold.

Pics of what I'm talking about.

[cericd]

Found a thread that answers my "original finish" question https://www.67-72chevytrucks.com/vbo...d.php?t=670464. Still not sure about the screw sizes.

[DaHos]

#10 sheetmetal screw with 5/16 hex

[cericd]

Originally Posted by DaHos

#10 sheetmetal screw with 5/16 hex

Hex head? My originals that are left are pan head Phillips.

[54blackhornet]

I have the original set up on my 71 C20. The screws are sheet metal with hex heads.

[cericd]

Originally Posted by 54blackhornet

I have the original set up on my 71 C20. The screws are sheet metal with hex heads.

Interesting, wonder if they made a change from 70 to 71. I feel like the "patina" looks pretty uniform from screw head to stove metal to lower nut & bolt. I guess I really just need to figure out if all the holes are the same size. Also, I can't find a repop of the heat stove so I guess it's not reproduced.

[54blackhornet]

I am referring to the two used to secure the pipe up to air cleaner.

[cericd]

Originally Posted by 54blackhornet

I am referring to the two used to secure the pipe up to air cleaner.

Oh, I wasn't sure if they were all the same or if the two for the pipe were different. Thanks for confirming.

[cericd]

While doing some more searching through the forum I ran across a thread by IronCanine on the subject of heat stoves. davischevy posted a couple pics of his 56,000 mi C10 and it appears that all screws across the top are indeed hex head. It appears however that the two for the pipe have larger heads than the others. Looks like my two Phillips screws are OLD replacements.

Here are davischevy's pics.

[IronCanine]

I believe the hex head sheet metal screws are correct for both the tin to tin connection and the tube to tin connection. I don't think there is a specific call out in the assembly manual, but I'll check tonight as well as post some pics of originals I have at home.

Most of the time those tins came off and never went back on...but if they did, it wouldn't surprise me if a lost screw got replaced or if a hole was wallowed out and a larger screw stepped in.

Also, hardware could be variable amongst plants or time periods...so it is conceivable that other hardware may be seen. Every one of these that felt honest and original to me had hexes.

[Joesjunk]

Originally Posted by IronCanine

I believe the hex head sheet metal screws are correct for both the tin to tin connection and the tube to tin connection. I don't think there is a specific call out in the assembly manual, but I'll check tonight as well as post some pics of originals I have at home.

Most of the time those tins came off and never went back on...but if they did, it wouldn't surprise me if a lost screw got replaced or if a hole was wallowed out and a larger screw stepped in.

Also, hardware could be variable amongst plants or time periods...so it is conceivable that other hardware may be seen. Every one of these that felt honest and original to me had hexes.

I would completely agree

[davischevy]

Originally Posted by cericd

While doing some more searching through the forum I ran across a thread by IronCanine on the subject of heat stoves. davischevy posted a couple pics of his 56,000 mi C10 and it appears that all screws across the top are indeed hex head. It appears however that the two for the pipe have larger heads than the others. Looks like my two Phillips screws are OLD replacements.

Here are davischevy's pics.

I just looked at a 72 that I built over 30 years ago and it has the 5/16 hex head screw in the pipe. The K10 I am building now has 5/16 hex head in the pipe.

[IronCanine]

Parts manual calls for #8-18. All the ones I have are just that. Some have an M makers mark. 1/4" socket fits em all. I don't doubt that the tube screws could have been #10s from the factory. It makes sense, those are the screws really under a load. Also, the ones most likely to get wallowed out and get upsized IMO.

Also, Larry has previously made a point about what he has seen finish-wise on low mileage examples he's owned...and I've recently seen it myself. It appears the outer half of the heat stove tins was painted black and the inner half was unpainted. You can see it in the pic Chris posted of Larry's truck and in the rough original example shown below.

[IronCanine]

...

[cericd]

Thanks for all the great info and pics guys. What would you think the original finish on the fasteners would've been, black oxide? Any recommendation on a source for some new replacements? M maker's mark not necessary.