Some info on the 292 I6

[tony_rama]

Hey all
Trying to find out some info about the 292. I can find some stuff online, but so far I've only found info on the 292 as it came on the pre-'67 trucks, and as it came on the '73 and later trucks. Mine is a '68, and I'm curious if they're any different, or if it was the same motor all along.

[Wrenchbender Ret]

They are all basically the same. About 68 they put an outlet in the head for the temp. gauge sender. Most 68 up had holes in the ports for emision controls. About 66 they changed the flywheel bolts to 1/2 in. from 7/16. 73 up had different water pump & outlets with a smaller bypass hose & narrow fan belts. There are variations in the exhaust manifolds through the years & size of trucks.

[tony_rama]

Were the horsepower and torque numbers the same thoughout?

[Wrenchbender Ret]

Similar but not the same.

[Shaky]

Torque peak at 1600 rpm!

[cam.man67]

Huh, Well I'll be danged! I wish a PO wouldn't have ditched the 292 for a 350 in mine. Oh well, no truck's perfect.

[1968CHEVYC10]

dadgum, I'd always heard they had lots of torque but never seen any numbers, thats pretty good.

[RichardJ]

Why??
It doesn't matter where the power or torque is, as long as it is geared for it. Replacing the 4.56 rear gears with 3.54 gears woke the truck up. It pulls really well in the 60 - 80 mph range with little effort.
It isn't a race car, it isn't a new $50k Silverado, but it gets the job done.

[Shaky]

Well, it's good to make it down low on a work truck. And it adds to longevity when you don't have to spin too fast (although the piston velocity is high for a given rpm on a 292 due to the stroke, which increases main bearing loads significantly).

My understanding is that UPS had good luck in their trucks with the 292 for many years due to these characteristics. A high-winding 327 with a torque peak at 4500 rpm is a wonderful motor in a 'Vette, but kinda lacking when you have a full load in the bed and you're stopped on a hill.

[tony_rama]

I'm trying to get an idea of the 292's characteristics, because the one time I drove it out on the road, there was lots of noise, lots of shaking, vibration, got all the way into fourth, differentials screaming, and found I was only doing forty or so. Now I've poked around here just enough to know that you guys like the 292, and hold it be heresy to swap in a 350, so I'm trying to understand more about horsepower, torque, RPMs, gearing, and how all that affects the overall feel of the truck. I would like to be able to get it higher than 40, 60 would be plenty fast enough I'm sure, I don't need a speed demon. But I'm used to small Japanese cars, and this is very different. Behind the 292, I've got a 4 speed tranny, and 4.10 gears. Just want to understand how it all interacts so I know what to change (or fix) to make it alittle more highway friendly.

That page looked like all the info I need, but if I zoomed in on it, the resolution wasn't good enough to read it. What book did that come from?

Thanks
Tony

[Shaky]

I wouldn't call it heresy to swap out the 292 for a V8. It all depends on what you want to do with your truck. I have a soft spot in my heart for GM straight sixes because they took me so many places over so many years and did it reliably. When they did break they were cheap and easy to fix.

I just want to cruise around with it and not have to work on it all the time. I also don't want to sink huge amounts of money into it.

I'm restoring a '67 C20 with a 292 and an SM420 (granny-geared 4-speed). Most people would probably put in a more modern V8 and transmission. This would make it faster and a lot more sporty. However, I'm keeping the stock drivetrain and will just add a (very expensive) overdrive behind the 4-speed so that I can keep up on the highway. I just get a kick out of rowing that old cast iron 4-speed and listening to the big straight six.

Playing with performance parts on the straight sixes can be expensive. You can get so much more for your money out of a V8. If I was going to put an eight in my truck I would probably get a stock LS motor and modern transmission. This would make plenty of power and probably get better mileage than an old straight six!

As far as characteristics go, the 194-230-250 sixes are similar to the 292 but also different. They all have the robust 7-main-bearing bottom end and share a lot of parts, but due to differences in the bore-to-stroke ratio they act very different. The 292 has a very long stroke compared to its bore, which is why it makes so much torque down so low.

For a given rpm, the longer the stroke the faster the piston has to travel to go a further distance in the same time. When you spin a 292 up, it is putting progressively larger loads on the main bearings, so I try to stay away from that. The 4-barrel 250 I had like to rev, but that has a much shorter stroke.

Some people build some hairy 292s, but it costs $$$$. For me, on my budget, I've come to the conclusion that I'm going to keep my sixes stock and any performance work will be done with V8s.

As far as all the noise goes - I was amazed when I bought a '68 Biscayne with 24,000 original miles and fired up the 250 for the first time. It was quiet and smooth! All the other ones I had were high milers and rattled and clattered. Also, my 292 in my '67 C20 slipped the outer part of the balancer and vibrated like hell until I put a new one on.

You can put a higher (numerically) geared rear in and reduce rpm somewhat, but an overdrive (either different transmission or add-on overdrive) will really get you where you want to go without sacrificing the low-end.

All that above is my view on things. I'm sure others will have some other perspectives...

[Shaky]

Originally Posted by tony_rama

That page looked like all the info I need, but if I zoomed in on it, the resolution wasn't good enough to read it. What book did that come from?

Thanks
Tony

I got that spec page from a thread in the 60-66 section of this website. The guy that posted it gave me a link to where he got it, but it was still too small to read. I share your frustration.

The specs below are from my '67 Service Manual. Notice that all the sixes have the same bore but different strokes.

[tony_rama]

Lot of good information, thanks. As far as noise goes, the engine itself is fine, I think. My diffs, (or maybe the tranny?) howled like mad when I got her out on the road, louder and higher pitched the faster I went. Of course, max speed on that run was 45 or so. Also, the front end felt like it was riding on marbles. I plowed snow all last season, and none of these things were issues in my yard, but hopefully I'll get them all ironed out before snow flies again.

[capev86]

geez.....wishing my 72 burb c20 had come with a 292 instead of the 327's smaller bore sibling the 307. better numbers both in hp and torque and it is smaller displacement. a stroker is the way to go for normal driving and pulling any kind of weight (aka towing) as it moves the torque curve lower in the rpm band.

i do have a 406sbc to fix my problem, but i'd love to stick a 292 in like an early 50's chevy and bypass the 216/235 lackluster performance altogether. i was thinking a 50 or so 1 ton extended panel truck with a hot rod 292 (roller cam, electronic ignition, etc) would be awesome backed up by a 6 speed with dual overdrives. a 4.10 rear would round it out very nicely. a lot of that could be done in such a way as to appear like the factory (paint, shifter handle, accessories, etc).