Inliners International Forums General Discussion Engines 292 LP pistons.... detonation????

I'm rebuilding a stock 292 for my Chevy 1/2 ton 4x4 truck. This is not a hot rod,I'm replacing a worn out 250 with a 292.
I have access to a new set of Sealed Power 980P pistons in the correct size for very little money. I believe the 980P is the propane pistons?
Using a stock cam will the engine be detonation prone on regular gas ? If it won't detonate on 89 octane that'll be ok....Anyone have real world experience on this? thanks

I did build the engine. Milled the block .025 to get a reasonable quench of .055.. CC ing the heads an the pistons the actual compression came out to 8.95 with .040 LP pistons. A mild Schneider cam, .465 valve lift, 194-204 degrees duration at .050 lift.The rest of the engine used the 250 intake and exhaust...
The engine idles nice,makes decent power up to 4000 rpm and doesn't ping on 89 octane gas. I will try 87 octane now that the engine has some miles on it..

Nice build my friend. The right parts for kind of motor you need for the truck. I see you used Schneider cams. That is who I have been using for my cams for the last few years. I really like their products as well the way they treat me as a customer and the advice I receive when I call.

Good stuff to know. I'll be running 92 in my 292 as the compression will be between 9.5 and 10.1 compression. lol

Higher altitude than sea level requires less octane, so, if one lives at 2,000' or higher, experiment with lower octane fuels, buy higher octane when at sea level.

Ed

My engine has a stock 250 points distributor with the total advance at 34 degrees. This comes out to 8 degrees at idle.
Generally speaking a lighter vehicle with lower gearing will have less problem with detonation. My 68 Chevy K10 4x4 short step side weighs 3750 pounds on the scrap yard scale.....About the same as the GM listed curb weight.Stock gearing is 3.73

How are you doing Tony?

My 292 is pretty close to yours. 0.060" over LP pistons, 1.94 IN valves, same cam specs, long tube headers, Clifford, Carter AVS and HEI with 6* @ idle.

The C20 is 4600 lb at scrap yard scale. Last year I scrapped a late Corvair, cut up and stuffed in the bed. I'm pretty sure the 4600 from memory is correct.

3.54 gears with 285/70R17 tires.

87 octane in the winter for local driving. For towing or in the summer it gets 91 octane. AC is on full time, but doesn't affect anything.

Hey Richard,I'm just peachy.....My GM tech info lists a 68 C10 fleet side long bed 6 cylinder as 4060 pound curb weight.Of course this can vary a bit depending on equipment...
The 250 Monojet on the 292 isn't ideal but the engine has sharp throttle response at lower speeds.....