What GM create engine to buy for 3/4 ton 72 C20

[garyd1961]

Originally Posted by Jrainman

Agree with you, they have the lowest price, that is where I got my L31 from (Radley Chevorlet ) a few months back. They are great to deal with they had my engine at my door in 7 days, they also advised me that GM had a rebate program at that time , they took care of that also and about 2 weeks later I got a GM visa cards in the mail totaling $150.00 on them, So the engine costed a little over $ 1,800

I agree, they are a Chevy dealership so everything should be good to go. I just wouldn't buy from any billy bob selling engines on Ebay. If for some reason you should have a problem it's best to be dealing with a reputable company.
The center bolt valve covers were an improvement over the old style and a good improvement if you ask me. The adapters are just creating more places for the covers to leak. I'm as old school as anyone but since I installed my motor there is no way I would go back to the old perimeter style covers.
If you want more HP just install a good intake and 4 barrel carburetor with long tube headers and 2 1/2 inch exhaust. You can also install a MSD ignition system. All this will help the motor to breathe and the extra spark doesn't hurt. This is how I have mine set up and it has a lot of power.
You can also add 1.6 rockers on the intake side. I started to do this but learned I might have to drill out the holes for the push rods so I decided not to mess with it. I didn't want to pull the heads or take a chance of getting metal in my motor.

[jocko]

Originally Posted by garyd1961

You can also add 1.6 rockers on the intake side. I started to do this but learned I might have to drill out the holes for the push rods so I decided not to mess with it. I didn't want to pull the heads or take a chance of getting metal in my motor.

Have never had to do this and have used 1.6 rockers before. Where did you hear this? Is this Vortec-specific or something? Not the case with stock Gen 1 sbc.

[davischevy]

WE have 1.6 roller tips on both old style and vortec heads. As I remember we had to use thick valve cover gaskets.

[garyd1961]

Originally Posted by jocko

Have never had to do this and have used 1.6 rockers before. Where did you hear this? Is this Vortec-specific or something? Not the case with stock Gen 1 sbc.

I have never used 1.6 rockers but believe it's just for the Vortec heads. You may get by without drilling but some say you need to drill out the passages for the push rods with a 1/2 inch drill bit to be on the safe side.

[jocko]

Originally Posted by garyd1961

I have never used 1.6 rockers but believe it's just for the Vortec heads. You may get by without drilling but some say you need to drill out the passages for the push rods with a 1/2 inch drill bit to be on the safe side.

Interesting, thanks, had never heard of that. More reason to install the cam one really wants up front! I think the HT 383 cam might be a nice addition to the L-31R, as some have mentioned above. I can't think of any reason that wouldn't work just fine, and with standard 1.5 rockers.

[truckster]

Originally Posted by jocko

Interesting, thanks, had never heard of that. More reason to install the cam one really wants up front! I think the HT 383 cam might be a nice addition to the L-31R, as some have mentioned above. I can't think of any reason that wouldn't work just fine, and with standard 1.5 rockers.

I've got the HT 383 cam in mine with the stock rockers. I haven't fired it up yet, but it should scoot pretty well. As far as opening up the heads for 1.6 rockers, it's hit-or-miss. You definitely need to check clearance for the pushrods, or you could end up bending or breaking them.

[jocko]

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?

[garyd1961]

That's a flat tappet cam, I would stick with the L31-R and a hydraulic roller. There is no way I would pay more for a motor with a flat tappet cam. GM didn't switch to a hydraulic roller for nothing, they would have stayed with the cheaper flat tappet if they didn't have a good reason to switch.

[jocko]

Thanks Gary. Yeah, that's why I was surprised, ALL their other Vortecs have roller cams that I can see, and even one of them, at one dealership, lists the HT383 incorrectly with a flat tappet, so thought maybe this one was incorrectly documented also. I agree, better to have a roller. I think I'd be happier with the lower torque band of the L31R anyway to be honest. If ONLY GM would come to this website and realize they need an L31R with an HT383 cam in it, all would be solved Ha. Actually, to add the exact HT383 cam, ext bal flywheel, intake, gaskets, and bolts - the L31R + all that runs between 26-2800. Not bad at all - just have to install the cam, intake etc, not a big deal.

I saw above a few mentions of painting the crate motor chev orange - does anyone have any pics of a crate L31 painted orange they could share? I'm curious how noticeable the manifold differences are - I'm assuming not very.

And, my apologies to Chilly, I feel I've hijacked a bit.

[davischevy]

Originally Posted by jocko

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?

I have a 330 Horse for my 67 SWB, but it's still in the crate, so I can't help on how it feels.

I do know the 383 we have in the BLazer is fun.

[davischevy]

RE; orange paint.

A friend of mine put the L31 in my 55. He didn't paint it. It would look a lot better to me painted Chevrolet Orange.

I have not warmed up to the center bolt valve covers. I am going to buy adapters, so I can put old style valve covers on it.

[Chilly178]

Good info here. If one were to go the L31-R route how would that work with the electronic fuel pump?

[jocko]

He's referring to the HO350 I posted the link to in post #57.

[jocko]

Originally Posted by davischevy

RE; orange paint.

A friend of mine put the L31 in my 55. He didn't paint it. It would look a lot better to me painted Chevrolet Orange.

I have not warmed up to the center bolt valve covers. I am going to buy adapters, so I can put old style valve covers on it.

Agreed - a vortec looks much better (to me) with the adapters and Gen 1 valve covers. One can hardly tell. And this shows the vertical manifold bolts - they don't really stand out to me once the valve cover thing is remedied. Paint the whole thing stock orange and it will kinda disappear. I think I have my gameplan.
Guess I just answered my own picture request, forgot I had this one saved somewhere.

[6T7 C10]

Originally Posted by Chilly178

Good info here. If one were to go the L31-R route how would that work with the electronic fuel pump?

I am doing this right now to an L31-R on my pickup. I installed an electric fuel pump on the frame under the tank and wired it with a circuit breaker and relay kit, and added an impact switch (for safety) run off the ignition key. Depending on the pump output it would be wise to run a fuel pressure regulator set around 5#.
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[truckster]

Originally Posted by Chilly178

Good info here. If one were to go the L31-R route how would that work with the electronic fuel pump?

If you're going to use a carburetor you'll need an electric fuel pump and a fuel pressure regulator.

[davischevy]

I run an electric fuel pump with my L31.

[garyd1961]

Some pumps don't need a pressure regulator. Right now I'm running a Holley Mighty-Mite without a regulator. I really didn't think the little Mighty-Mite pump would be worth a darn when I first saw it but it has worked flawlessly so far.
If any of you do get the Mighty-Mite be aware there are 2 different versions. I have the 400 hp rated one, don't have the part # right now.

[Chilly178]

Hey Gary could you post a pic where you mounted the fuel pump? Says that it should be within a foot of your tank.

[Dhaak64]

Great disuccusion on the L31r.

I’m looking to run my factory clutch linkage on my 64 c10. Does anybody know if the block has the provision tapped for the ball stud? I’ve looked all over and can’t find any clear pictures, or information on this. Thank you.

[geezer#99]

Easy to make a bracket.
Here’s some ideas.

https://www.google.com/search?tbm=is...10.4ihshz4dKAQ

[B. W.]

Originally Posted by Dhaak64

Great disuccusion on the L31r.

I’m looking to run my factory clutch linkage on my 64 c10. Does anybody know if the block has the provision tapped for the ball stud? I’ve looked all over and can’t find any clear pictures, or information on this. Thank you.

My L31 did not. The boss is there, I drilled & tapped mine.

[Dhaak64]

Thank you for the responses. I feel confident to drill and tap the provision on the block after some research.

[Killer Bee]

if I decide to buy a crate motor over building one of mine, I'm defintiley going this route..

just under $6k with EVERYTHING complete.. huge time saver hunting all that down..

if GM packaged a 383 turn-key like this, I'd already be all over it..

Chevrolet Performance SP350 Turnkey Long Block Crate Engines 19367084

They put out 385 hp with loads of low-end torque. In fact, the engines produce 405 lbs.-ft. of torque by only 3,600 rpm for a thrilling feeling of immediate performance

[SC1969c10]

I just dropped a crate 350 from advance auto. 4 year warranty for $1700. They also offered a performance version for 2700 but only had a 1 year warranty.
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