The Stovebolt Site Forums The Shop Area Engine Shop '47 3100 Rebuilt 216 upgrade questions

I am helping my dad get his 1947 truck back on the road after close to two decades of dormancy. Engine was rebuilt by an old-timer shop in Abilene Texas in about 1992 when a lot of the truck came apart for a freshen up. Circumstances saw the truck have to be left, in this apart state, in a barn with the fresh engine sitting in place.
The years were fairly kind to it but it froze up due to some very light ring-to-bore rust.
My questions are of the 'what do I have here' variety. I think it was rebuilt with a 235 crank using some sort of inserts that allowed for the use of an oil pump and 235 pistons. My dad specifically remembers that the valves and seats were upgraded to accommodate modern fuels. Anyone who would know by looking what has been done, please have a look at the pictures here and tell me what I'm looking at:
1947 3100 216 engine tear-down pictures.

Thanks!

They probably installed "Hardened" valves to deal with the unleaded fuel. However, I though the 216 and 235 were heavy duty enough to handle the unleaded gas in stock form!

Also, before you tear the engine out, pour some marvel mystery oil through the spark plug holes and let it sit for a couple days. That could very well free up the engine. Then the previous rebuild would not have been a total waste of time and money.

It's hard to tell from the pictures if the rod bearings are inserts or not, but a common upgrade would have been to machine the stock 216 crank for inserts. The pistons are more than likely alluminum replacement pistons for the 216. The oil pump came from the factory, as the only bearings that were "splash" oiled were the rod bearings, a pump was used on the 216's to provide oil to the cam bearings, main bearings, and the valve train.

Hope that helps.

We must be on the same page on the '47 216. I just found one in a crate in Yakutat, Alaska while up there on a fishing trip. That is an old Navy Sub base. The military sold all of the stuff they didn't want to haul out to locals. This guy still has crated GMC 270's and 302's. I'm in the process of converting this one to a full pressure oiling system and also machining the block at the back crank oil seal to use a later design seal there. When it goes back together it will go in my '32 Chev. Confederate four door daily driver. I'm also using a late model distributor and a much more dependable intake manifold with w Weber carburetor up on it plus cast iron exhaust headers. This won't be a racer but it will get me around dependably for years to come. I also have a 261 with a 12 port AMD head on it for my racing thirst and it is in a '37 Chevy coupe with a complete redo in the undercarriage. For you, think about an updated HEI distributor, High Lift Rockers, improved fuel delivery and also updating the transmission of this truck to a later full synchronized four or five speed. OR.. how about a automatic like the T-400? It only takes money (and lots of it!) talent, tools knowledge and a place to work.
Normbc9

I think it would be the rods that would be machined to take inserts. You most likely have a 216 motor there. The 235s of that style were in the large trucks.

I drive a 51 Chev. Bel Air with a 216 bone stock and have had no unleaded fuel issues of any kind. My neighbor works at the Chevron Richmond, CA plant and the engineers there told him not to worry about that question if he uses their gasoline (that must be a sales gimmick)because one of my Vol. Firemen works at the Occidental (old 76) refinery up the bay a piece and they told him the same thing.
Normbc9

Looks like aluminum pistons. The rod caps still have dippers and the oil pan the troughs. It still has the oil distributor thing on the driver's side. If it had been converted to oil pressure rods (by drilling oil passages in the crank from the mains to the rod throws) then the dippers, troughs and oil distributor thing would be gone. It was and still is a common upgrade to machine the rods for inserts. And it could have a 235 crank too. It could have been bored to 235 diameter. It could easily be a 41-49 235 from a 2-ton truck. What do the bores measure? stroke? What is the serial number stamped? block casting number?
Since you have gone this far I think you should pull the pistons and inspect the rings to insure they are not frozen to the pistons. Probably only needs a good cylinder honing and put back together with new gaskets - and run it!!
Good luck - looks a good motor to me.

Thanks for all the responses.

I guess I should clarify a few things:

This is the original engine to the truck, so it's whatever flavor of 216 a 47 3100 would have.

The engine turned over with a little effort once the head came off. Am considering pulling the pistons for inspection but the rust in the bores is very very light -more of a discoloration than anything. It can be seen in the picture of the bores.

Re the valves/seats: I think it was done because it was the 'right' thing to do.

OK, so it looks like a stock 216 . How did you do that thing to the thermostat housing? Here's the thing with the bore rust. If you leave it , it might just be worn away by the rings, but the proper thing to do is remove the rust. you have to pull the pistons to do this because you cannot properly clean the residue from the rings etc if you dont. Not a big job, just time spent doing it carefully. Think surgical cleanliness as you are assembling the engine.

By the way, I love the old hand painted lettering on the doors! Very cool. I vote to keep that.

Dusty -I think maybe that corner broke off when my dad was removing it- I wasn't there to see. I am thinking the same think -there will be no unknowns if the rings and bores are cleaned up.

Frank50 -absolutely the doors will be left as they are. I am hoping to find front fenders in the same color with matching patina someday.

I did a write up of my last bit of work on the truck for my blog: http://giuliettas.com/2011/03/31/project-dads-1947-chevy-3100-part-2/