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**jocko** · 11-22-2017, 06:54 PM

So, here's an interesting find from Radley - since we've been talking about putting an HT383 cam into an L31R, isn't the below kinda "that"?

350, 9.1:1 (the 383 compression ration though, not the L31's) - but a higher lift cam than even the HT383. I sure don't need a forged crank like the 383, so can save some $ there. So basically an L31R with a slightly lower (but still good - same as the HT383) CR and a more aggressive cam than the L31. While not as much hp/torque as the HT383, still a decent improvement over the L31R, and you don't have to rip a factory built one apart to install a new cam... This kinda seems like a factory version of what I'd want to do to an L31R anyway. Hmmm. (the chrome would have to go though...

But it does state flat tappet cam - which I am wondering if that's yet another typo...

https://www.ebay.com/itm/OEM-NEW-Che...19.m1438.l2649

Specifications:
Power: 330 HP AT 5000 RPM, 380 ft. lbs. of torque @ 3800 RPM
Displacement: 350 CID, 5.7L
Bore x Stroke: 4.00” x 3.48”
Compression Ratio: 9.1:1
Block: Cast Iron, 1 piece rear seal, 4-bolt main caps
Crankshaft: Nodular Iron
Connecting Rods: Powdered Metal Steel
Pistons: Cast Aluminum
Camshaft: Hydraulic Flat Tappet
Cam Lift: .435” Intake / .460” exhaust
Cam Duration AT .050”: 212 deg. Intake / 222 deg. Exhaust
Lobe Separation: 112.5 Degree
Cylinder Heads: Vortec Cast Iron, 3/8” pressed-in rocker studs
Combustion Chamber: 64cc
Valves: .194” Intake/ 1.50” Exhaust
Rocker Arms: Stamped Steel, 1.5:1 Ratio
Valve Springs: 10212811
Balance: Internal
Maximum GM Recommended RPM: 5500
Ignition Timing: Base 10 degrees BTDC, 32 degrees total

Here it is for $2500 ($300 less), but I'd probably still go the dealer route - Radley. Reputation.
https://www.ebay.com/itm/OEM-NEW-Che...4383.l4275.c10

EDIT: an important note, the power and torque band is noticeably shifted north in this motor than an HT383, or even the L31R. Guess there's no way around 383 price if you want 383 #'s! Ha. Can build it for a little less, or go with the warranty factory crate. I know what I want (383). I'd have a hard time choosing between the L31R and this HO350. L31R may be more usable for a truck. That's what it's made for. The HO 350 is perhaps more of a Camaro crate... Anyone have both that can speak to the seat of the pants diff between an HO 350 (19210007) and an L31R?

11-22-2017, 06:54 PM	#57
jocko Senior Member Join Date: Oct 2009 Location: Godley, TX Posts: 17,934	Re: What GM create engine to buy for 3/4 ton 72 C20 So, here's an interesting find from Radley - since we've been talking about putting an HT383 cam into an L31R, isn't the below kinda "that"? 350, 9.1:1 (the 383 compression ration though, not the L31's) - but a higher lift cam than even the HT383. I sure don't need a forged crank like the 383, so can save some $ there. So basically an L31R with a slightly lower (but still good - same as the HT383) CR and a more aggressive cam than the L31. While not as much hp/torque as the HT383, still a decent improvement over the L31R, and you don't have to rip a factory built one apart to install a new cam... This kinda seems like a factory version of what I'd want to do to an L31R anyway. Hmmm. (the chrome would have to go though... But it does state flat tappet cam - which I am wondering if that's yet another typo... https://www.ebay.com/itm/OEM-NEW-Che...19.m1438.l2649 Specifications: Power: 330 HP AT 5000 RPM, 380 ft. lbs. of torque @ 3800 RPM Displacement: 350 CID, 5.7L Bore x Stroke: 4.00” x 3.48” Compression Ratio: 9.1:1 Block: Cast Iron, 1 piece rear seal, 4-bolt main caps Crankshaft: Nodular Iron Connecting Rods: Powdered Metal Steel Pistons: Cast Aluminum Camshaft: Hydraulic Flat Tappet Cam Lift: .435” Intake / .460” exhaust Cam Duration AT .050”: 212 deg. Intake / 222 deg. Exhaust Lobe Separation: 112.5 Degree Cylinder Heads: Vortec Cast Iron, 3/8” pressed-in rocker studs Combustion Chamber: 64cc Valves: .194” Intake/ 1.50” Exhaust Rocker Arms: Stamped Steel, 1.5:1 Ratio Valve Springs: 10212811 Balance: Internal Maximum GM Recommended RPM: 5500 Ignition Timing: Base 10 degrees BTDC, 32 degrees total Here it is for $2500 ($300 less), but I'd probably still go the dealer route - Radley. Reputation. https://www.ebay.com/itm/OEM-NEW-Che...4383.l4275.c10 EDIT: an important note, the power and torque band is noticeably shifted north in this motor than an HT383, or even the L31R. Guess there's no way around 383 price if you want 383 #'s! Ha. Can build it for a little less, or go with the warranty factory crate. I know what I want (383). I'd have a hard time choosing between the L31R and this HO350. L31R may be more usable for a truck. That's what it's made for. The HO 350 is perhaps more of a Camaro crate... Anyone have both that can speak to the seat of the pants diff between an HO 350 (19210007) and an L31R? Last edited by jocko; 11-22-2017 at 07:05 PM.