The 292 is probably GM's "best" straight six,not counting older ones like the 235,261,and 302 GMC straight sixes they had in the 50's and very early 60's...the 292 makes its highest torque at 1600 rpm,lower than even a diesel like a 6.2 does...you can lug one down to 15 mph in high gear and step on the gas ,and it'll pull like crazy with no bucking or pinging...if you want low rpm rock crawling ,snow pushing torque,you'll like a 292..they used them in C-60's and busses back in the 60's and 70's,proving they can hold up under heavy useage...
The straight sixes with the "bad" reputation for spark knocking themselves to death were the post '75 250's that had the "integral head" design,and the 2 bbl versions were probably the worst..I had three of those engines,one was a 1975 one bbl carb version that pinged constantly and was herky-jerky around 35-40 mph,never could get the surge out of that one bbl carb,even after messing with the APT screw,(though it did improve some)...that one eventually stripped the cam gear teeth off,so rather than fix it,I swapped in a 307 V8 I had from a '71 Burb 4x4 I parted out...with a '75 Vega saginaw 4 speed behind it (was a 2wd K5)..
The other two 250's I had were a '79 and a '81 in a C10 and my 81 G-10 van,both ran good,but were pretty gutless,and I tried putting a Edelbrock on the '79,but the secondaries made it go slower and bog ,not run better!--I ended up removing the linkage so it was running only off the primary barrels..it ran better that way than with the POS Rochester E2SE carb,(I made a home brewed carb adapter to make it bolt to the intake)...but the engine had pinged for 100K with the original setup,and at 117K,the #6 piston gave up,the top lands came off,exposing the rings,and the cylinder didnt like the peices getting crammed between the piston and cylinder walls...I put a '86 305 V8 in that truck,mostly because I could not FIND another straight six here anywhere...people toss them away when they yank one out of an old car or truck here...
My van I decided was too slow and dangerous with a 250 in it,so I pulled it out and swapped in a 307 V8 from a '73 Malibu...bad choice,that was the last year for those engines,and the first with EGR...was rated at a whopping 115 HP,the six I removed was rated at 130,and though the V8 had more tourqe,it sure dont FEEL like it does,especially after I had to put a used diff with 2.73's in it when the original one with 3.08 gears wiped the diff case out...it'll go 78 mph in second gear now,but takes a mile to get there (still better than the 53 mph with the six and 3.08's,but not much!)...it gets less mpg's than the 250 did too,but at least it can get out of its own way better...looking back,I think I should have just left the 250 in it and lived with it,it was a lot of work for little gain,really.
Be aware the 292's have different locations for the engine mount on the passenger side,the block is higher and differs from a 250,the fuel pump and distributor swapped places,and you'll need that bracket off a 292 truck to bolt to your frame in order to bolt a 292 in it...other than that its a simple swap...
I like straight sixes,very simple,easy to work on,and hardly ever NEED work,if you give one any kind of care...the 292's aren't known for great gas mileage though,15 mpg would be the most ,I bet 12 would be more likely with low gearing..maybe you can put big tires on the truck seeing the 292 will pull at low rpms,the closer to the 1600 rpm maximum torque speed you can keep it at cruising speed,the better mileage you'll get...
I don't need a powerhouse for what I do right now.
