The Stovebolt Site Forums The Shop Area Engine Shop 292 question

Anyone have a clue what automatic trans Chevy used behind a mid 70's 292 in a heavy 3/4 or one ton truck? I have the ability to buy the engine and trans at very reasonable price. Just wondering how it would work in my 42 1.5 ton. Thanks for your response.

I've always thought that 292 powered trucks used extra heavy duty 4-speed manual transmissions. :confused:

Never heard of one run behind an automatic as stock equipment. Of course because the 292 has the SBC bellhousing your tranny options are numerous.

-ftyler

Yeah, when did they switch from the SM420 4spd to the SM465? I understand they were both pretty rugged with a granny low, but the latter was a bit larger in dimensions (length mostly?).

Just had the engine dropped off this afternoon. I haven't had the chance to identify the transmission other than make a drawing of the oil pan. The casting #'s indicate the engine is a 73-84 292, has electronic ingnition & no smog controls (it even turns over). I have another 292 with an sm465 trans. however, there is a big hole in the side of the block. Hopefully the combination of the two will provide one good engine. I'm wondering though if the crank ends have different bolt patterns for the appropriate flywheels. Any ideas? How about a site for auto trans info? Thanks for your help guys and gals.

Crank ends should be the same except earlier blocks had 7/16" fine thread holes for flywheel bolts and later cranks had 1/2" fine thread holes. Early cranks can be drilled and tapped for the larger bolts.

I would be interested in what you find if any differences. My 292 had a big honkin flywheel on it like it was in a bus or something and will be getting a flexplate for an automatic tranny in the near future - once I figure out what to get.

SM465 came in 68. It takes a bell with a 5-1/8" hole, vs. 4-3/4 for the SM420. Another possible tranny would have been the Clark 5 speed, mostly in school buses and 2 ton trucks.

On most engines in general the differance between the automatic version and manual version is that the crank end isn't always drilled in the auto version for the pilot bearing that the manual clutch needs, but they almost always use the same bolt pattern. It would seem to me that as long as you can find a flexplate (I think one from a 250 should work) that you will be able to use a 292 with a slushbox.

I finally had the opportunity to remove the transmissions from both of my 292's, I was very happy to find the ends and bolt patterns on both cranks were identical. That's the good news. The bad news. I removed the spark plugs from what I thought was my good engine and it spit water out of the #6 cylinder when I turned it over. Is it possible water could have gone down the carb into only one cylinder? It was too much to be condensation and there was none in the other cylinders. The engine has been out of the donor vehicle for a while and kept indoors. It was however, delivered in a rain storm with the carb exposed. Thanks for your responses. Here are the pictures of my project vehicle just before I started my resto.

web page

The water in the single cylinder could have easily come from rain coming in the carb. Especially since it was #6 - motor could have been tilted toward the back and intake valve open, water could have run right in.

Chevy did put some autos behind 292s back then. We had one in the motor pool at a ammo plant. It was a Chevy 1.5 ton, maybe bigger. I thought it was an Allison because it had a retarder on it. But I never checked it out. If I remember right it was a late 60s truck. I do remember the truck well. It was worked hard ran hot and used some oil. As I fueled one hot day I started to add a quart of oil. We had bulk oil and used a gallon can with the pull down type spout. Unkown to me, the valve was stuck open. When I pulled it down it poured oil over the engine, including the very hot exhaust manifold. It started making lots of white smoke. I yelled for the fire extinguisher. The guy says what for? I says you'll see real soon if ya don't get it. About then it burst into flame. I had it out in a heart beat, as soon as the fire extinguisher was in my hand. It didn't hurt anything we could see. We never told any one about it. They would have had a fire truck standing by every time someone wanted to fuel. Mike

Ken, thanks for the info. I feel a lot better now about the water. It was hauled just as you described.

Slomoe, when I was about 10, my dad had 65 Suburban with 292/automatic, would smoke the tires. He had a friend who was in the trucking business and quite conservitive, he had a chevy pu about the same age with a 250/standard he ragged my dad about the gas guzzler he bought, ironicaly the 292 was more efficient when loaded. Anyhow, I figured out the auto was a TH350, but I'm swapping for the SM465 unless I can find a good NV4500, reasonable and local.