Some info on the 292 I6

[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...

[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.

[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.