I know the JM20-22 is not the most current technology but its what I have. If my Cutlass sells I won't have a home for my 455. I do need a truck. Can't help but wonder how well that cam would work in a truck.


I will haul firewood and gravel in my utility trailer but never horses or huge camper trailers.
Thoughts?

 

The 260h comp cam worked really well in my 350 had plenty of grunt at cut out at about 5k rpm. Would probably be good in a 455 too.

 

What's the compression ratio in the 455? Gear? Trans?

 

If memory serves (and I'm not so sure about that) it would be 9.5?
It has 2278P pistons and C heads that to my knowledge haven't had any heavy milling done to them.

T350 gear? don't have the truck yet. Gears can always be swapped but initially I'll run whatever the truck came with. (Assuming I go this route)
Seems like my old C10 350 T350 came with 3.08's

 

I have the JM 18-20 in an 80 GMC with stock converter & 3.73 gears. It is 0.060 over 455 with 10.2:1 compression & ported C heads. Running an Edelbrock performer & an 750 AED carb & MSD electronics & headers it put 540 ft lbs to the ground on the chassis dyno @ 3850 RPM.

Very nice truck engine.

 

Got a dyno sheet by chance?

 

I appologize. I made a mistake. I was thinking about FLYWHEEL number not the wheels. Obviously a huge difference. I should have read it again before I posted. Thanks for catching my blunder.

The observed values for this engine were 325 hp @ 4500 & 427 TQ @ 3500 rpm to the ground. This was in Lethbridge AB & the net flywheel numbers in Lethbridge were 406 hp & 534 TQ.


Sea level corrected the flywheel power was 447 hp & 587 TQ. I do not recall what the correction factor what that day. Corrected altitude in Lethbridge is usually between 3500-4500 ft.

Those are the numbers that were provded to me. I will look to see if I can find the dyno sheet.

A lot of people are down on some of the old Mondello camshafts. I agree that there are better choices but I have had reasonable success with the JM 18-20 in my truck engine & I do have the JM 22-25-10 in the 455 in my 65 442 (no dyno work done on that car).

 

Those camshafts aren't made by Engle anymore some of their grinds are actually compcams but some are a third party I don't know who. We had a nasty debate last week so buyer beware if you buy from Mondello ask who it's made by and don't forget to degree it to verify the specs.

 

Actually, there is no such thing as a JM20-22 now. It is a JM20-22 Extreme and is a generic grind made by someone that sends the cam in a white box with no information.

Anyway, you can order the ENGLE 20-22 direct from Engle and it is the same cam that Mondello USED to sell. If you have a Mondello JM20-22 from the good old days then you are just fine. It is a great cam and I still order that grind direct from Engle to this day. In fact I am putting a 455 in my convertible that has that cam in it. It has always been a strong performer.

In my high school car it went 13.001 on street tires (BFG Radial T/A's) so I'd say it has plenty of power. I don't know about 534 ft/lbs of torque but it's got enough to make you smile.

 

Mines an old one, came in a Engle box.

 

Run with it...and don't look back. Use Valvoline VR1 oil from break in on. Either 20W50 or 10W30 or mix the two for a 10W40ish blend.