Inliners International Forums General Discussion Engines 292 Truck Engine Build

Hello all!

I’m starting a build thread for the engine I want to use in my 1953 GMC 2-Ton truck project. This truck will be updated with a more modern suspension, brakes, and tires from a compatible (in GVW) medium duty truck. It needs to be safe at modern highway speeds. My goal for this truck is to be able to drive across the country and safely transport back heavy stuff. One of the first things I want to use this truck for is to bring home a crankshaft grinder.

I looked long and hard at the idea of building a 302 GMC inline-6 engine for this truck. But the cost and difficulty of finding parts made it impractical for this project. After a lot of careful research, I feel the 292 is a good choice. Parts are still somewhat available, and there are quite a few people out there who know a lot about and love these engines.

A little about me:

I’ve been a precision machinist and tool maker now for over 45 years. This will be my first experience being an engine machinist. Does this make me an engine builder? Not even close. But I’m hoping with luck, my existing skill set will transfer to what I’m going to try here. I also hope that some of you on this forum that do have engine building experience will help guide me when I get stuck.

Please know, I am always impressed and interested in the clever work people do to extract as much power as possible from the internal combustion engine. This build will NOT be that. I’m only interested in improvements in torque and power in the lower RPMs. This engine will have a 4,200 RPM red-line, and spend most of it’s “useful” life between 1,600 and 2,400 RPM.

I have found two 292’s to play with. The first one unfortunately has a block that looks like it will not clean-up at 0.060” over bore. I might try and put 6 sleeves in this first block as a learning exercise. On the second engine, I still need to pull the head off, and dial bore gauge the bores to get a better idea of what I’m working with.

This build thread will not be something that happens fast. This project will take some time. Some of that is because I’m still trying to figure out the final recipe for this build. And mostly because I will be learning a LOT during this project.

Below is an image I managed to upload to the Photo Library here on the Inliners forum. It’s an image of the first 292 engine I found, mounted to an engine stand I built a few years ago. Looks like I need to make a longer drip pan!

Thanks for taking a look.

David

improvements in torque and power in the lower RPM:
1. larger engine
2. higher static compression ratio

Almost every other mod only increases power above your desired RPM range.

You will have fun with the challenge.
Don't put 6 sleeve in a 292 or a 250 for that matter. The block is already not super strong. You will remove too much strength of the base block casting.
I am willing to help as much as possible. Many people will benefit from your posting the knowledge out here.

Agree with Tom. A sleeve is only going to be as strong as the material supporting it, and these blocks have thin decks and sometimes thin cylinder walls at .060 over. So even a single sleeve can be iffy unless you have a Mexican block, especially since your block is already .060 over now, and you can bore into the water jacket removing needed support for the sleeve.

12bolt has .065 pistons in stock, if your block can hone clean at that.

OK, The players are showing up! Good job figuring out the picture posting puzzle!
This build is like the one I've been pondering here for many years with no build yet. I have all of the parts, or thought I did until TLOWE started printing intakes.

I have built many engines but not a 292 so my information is gleaned theory. My engine is for my '68 C20 flatbed dually, low rpm truck use. Now that the 350 has died I'm ready. Originally it was to be Turbo/injected but have ,at least for now, scrappers the turbo. That was one way to add inches. I don't think it is worth it for what I will be doing. It's always there with a piston change and maybe a different head. We have discussed some of what you want before but I want the hear what answers you get and maybe add some ideas.

Thanks for all the replies!

I was afraid the blocks where too thin for sleeves. I think it was on Tom's 12Bolt site? or maybe on this forum? I saw some images of a block he sliced up. The cylinder walls do not look very thick. I can post some of those images here if Tom says it's OK.

I have read over on the Speed-Talk forum about a technique where a very thin sleeve (thinner than normal) is used with a 0.0005" to 0.001" interference fit to help with distortion. It's also recommended to use a anaerobic sleeve retainer like Loctite 640. Of course, the use of a sleeve retaining adhesive then opens a forum discussion "can of worms" about whether it hurts thermal transfer between the sleeve and block...

Tom: I saw those beautiful forged pistons on your site offered in a 0.065" over-bore. I think you call them the "Block Savers." Because this engine will be used in a heavy truck, and will see long events with the pedal to the floor, I would like to keep the cylinder walls as thick as possible. I'm told this should help with cooling. Maybe a compromise would be a partial coolant jacket fill at the bottom, and add an oil cooler to the engine?

What I need to do next, is get both of these 292's fully disassembled and cleaned. I can then magnetic check for cracks, and pressure test the heads and blocks. I'll then measure the bores, check the decks and mains for straightness, and finally sonic check all the cylinder walls for thicknesses. This would at least let me know what I'm starting with. Fingers crossed I have at least one good block.

I will say that I consider this project to be like most of the things I do. For me, the most fun is learning something new.

In the end, all of this will be a collection of wins, hopefully few losses, and a whole lot of compromising.

David

Well, you really only have 2 viable options at this point for a block. Either go bigger with the bore with the .065" pistons, or use the other block. Even sleeving with thin wall sleeves isn't an option. The problem with other forums like Speed Talk is they are 99% V8 knowledge based, and thin wall sleeves dont protrude into the water jackets of hardly any V8 block because they are considerably thicker than the thin design of these 6 cylinders. Any money you spend after you do try to sleeve the cylinders with be futile, and end in disappointment for you.

CNC,

I completely agree with you and appreciate your knowledge. It's why I'm here. People like you know what can realistically be expected because of your experience. Even though I wish I could, I have no plans to try and sleeve a block. I was only sharing what I find.

I will be very curious to see with the sonic thickness gauge how thin this stuff really is.

David

Santucci mentions using a step bore and a thin chrome moly sleeve to give a good stiff bore. Any thoughts? Where might such a sleeve be obtained?

Darton can make them to your specifications.The thin wall style they have are around .060" thick, and are replacement sleeves more specific to aluminum race blocks like Rodeck and Donovan that have an additional 1/4" or more of material surrounding the sleeve to support it. These blocks can be as thin as an 1/8" or less. You'll remove half of that thickness to bore out to install a sleeve. Unless you have a Mexican block that is much thicker, you'll not end up with a better block by sleeving one. Leo's comments are mostly race oriented on this matter and for blocks that will be filled. So not too relevant for non-race applications, unless again, its regarding a Mexican block. We wouldn't even consider a non-Mexican block to start with because our cutoff for wall thickness was .125", and most of them were below that at .060" or less on the major thrust side.