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

[Chilly178]

Hello, a few months ago the 350 in my C20 started knocking. Instead of rebuilding it I am looking at the small block create engines by GM. http://www.chevrolet.com/performance/crate-engines Specifically the SP350/357 looks pretty good with the Vortec heads and hydraulic roller cam,
little expensive though.http://www.gmperformancemotor.com/parts/19367082.html anyone have any experience with these and know if it works with mechanical fuel pumps? And what parts do I need when buying a deluxe engine, also would this engine work with my current "thin belt" setup and pulleys? Or do I need a whole different serpentine system. I plan on keeping the same SM465 and Eaton no slip rear end. What crate engines are you guys using? Or am I better off rebuilding mine? Thanks.

[52napco]

Rebuild yours with a mild rv cam... I bought a 350 crate back in the summer and it's a bit disappointing...wish I would have built mine instead.

[JMC1965]

Mine went kaboom and I just installed ATK HP32-C with the FITech EFI. Truck is a 67 C20.

Pretty happy so far (only 1 month in though so I’m still taking it easy)

http://www.high-performance-engines....ors-s/2195.htm

[truckster]

If you want a crate 350, the L31 Vortec is an excellent choice. You'll need an intake manifold and electric fuel pump, but you'll get a one-piece rear main seal, a roller cam, and the best-flowing heads GM ever produced for the SBC. It should be good for around 300 HP, but the usable torque curve is much broader than that 290 HP engine you're looking at.

[mike16]

look carefully at where the usefull HP begins max's out and where torque begins and peaks.

wow those 290 hp crate motors are outreageous in price.

[Chilly178]

Yeah that's retail I think here is a different website.
http://www.gmperformancemotor.com/parts/19355659.html

[kwmech]

You could build from your 350 a 383 and still have money left over from that crate price

[6T7 C10]

I am about a month away from firing up my L31-R GM long block crate engine. It has been fun doing it and I would do it again. You will need an electric fuel pump as it is not drilled for a mechanical pump. I went this route for its simplicity, historical reference and bolt in ability versus a LS swap (nothing against LS swaps as that is on my bucket list). I gathered a HEI ignition, low profile dual plane manifold, small four barrel carb, serpentine belt system and ram's horn exhaust manifolds. Just for fun I put in .015" Fel-Pro head gaskets, 1.52:1 full roller rockers and painted the entire engine Chevy orange.

I think it would be a good choice for your C20 as that is what was in C20's in the 90's and the best GM had to offer in mass for the small block. Any mods and torque converter stall should be done with low end torque in mind.

[FirstOwner69]

In 2010 or 2011, I bought a 350HO Deluxe for my '69 C20. At that time, it was rated at 330HP with a Holley 670CFM carb. It is a Vortec head engine with a flat tappet cam. The Deluxe engines do not include a belt drive setup, serpentine or V-belt. When I bought mine, it included everything else except a fuel pump. I believe the current version does not include a fuel pump or water pump (mine had a long water pump). The flexplate on mine was a 153 tooth. I needed a 168 tooth. I'm using a short water pump. I'm also running ram horn manifolds which require different plug wires than those supplied with the engine.

To answer your questions...
- This engine uses a mechanical fuel pump like your original engine.
- The original alternator and power steering and brackets bolted right on. However, the front and rear top A/C brackets that attach to the heads did not due to the different style intake manifold used with Vortec heads. I fabricated brackets based on some brackets used in earlier/different SBC applications.
- If your current engine still has a points distributer, you'll need to set up the truck for HEI.

I am very satisfied with this engine and would buy it again. It performs well and runs great. A lot peppier than the original engine which is in storage. There is a hesitation when the engine is cold. I'm pretty sure all I need to do to fix that is do some tweaking to the Holley.

I did not buy mine at Summit Racing, but here's a link to it on their website.
https://www.summitracing.com/parts/n...SABEgLVZfD_BwE

[Chilly178]

Thanks for the info! I should have mentioned I don’t have power steering, AC. How does that work with the belt? I also have points so I would need the engine to come with HEI. I was looking at those engines but I’m hesitant towards them because of the flat tappet cam and having to add zinc to the oil.

[davischevy]

We have a 383 with vortec heads in a Blazer and one of the 290 HP crate motors in a K10.

The 290 HP engine is a very capable engine, but the 383 is a lot more fun to drive.

WE put roller tip rockers on both.

[jocko]

I have a personal "thing" about center-bolt valve cover hold downs, I have no idea why... While there are a few dual-valve cover hold down bolt and "old" intake manifold dual drilled heads out there, most of those vortec heads are for big inch small blocks (and pricey). As for aluminum options, I would rather have cast iron than aluminum on a daily driver personally.

While I'd like a 1 piece rear main seal because the 2-piece tend to eventually dribble on the floor, I've noticed they also require a neutral balancer, but externally balanced flexplate. Which I find a bit odd, but they do according to most of the info I've read on these.

Since what I REALLY want to do is just replace my stock (1x replaced) 350 with a stock GM 350 - and since I kind of prefer the GM new engines that haven't been over-bored, i.e. stock with the above criteria of perimeter bolt valve cover cyl heads and 2-piece rear main seals (all internally balanced), that leaves the 195, 260, and 290 hp GM crates.

Weird little nuances to these engines... I've yet to figure out the difference between the 195 and 260 hp engines... Both have the anemic cams (.383/.401 int/exh) but have 8.5:1 compression, whereas the 290 hp engine has a better cam (.450/.460) but 8.0:1 compression. One step forward and one step back.

While I really hate to crack open a brand new crate to upgrade the cam, that seems like the best option - the 195 or 260 hp crate with a subsequent buyer-installed cam upgrade. Nothing wild, but nothing dead like what it comes with either. That would yield a bit more potential in at least an 8.5:1 engine over the 290 hp's 8.0:1 I'd think. Anyway, speaking of thinking, I think perhaps I'll just continue my search for a stock 72 engine and rebuild it. Maybe make it a 383. Don't mind building them, I do enjoy that part of a resto. And even though I've rebuilt several, I probably still can't match the reliability and somewhat less mistake prone build of a good ol GM mfgr'ed engine. That's why I've been leaning toward a crate. My truck isn't numbers matching and it's not that important to me (although I WISH it was ). I do prefer them to at least look stock, thus my aversion to center hold down bolts on the valve covers I guess I don't see the 260 hp engine at GM or Summit anymore, only Jegs.

I DO wish they (GM perf parts) made a crate GEN 1 sbc with about 9-9.2:1 compression and a decent cam. To get that, ya gotta go with vortec these days it seems.

Perhaps a 383 vortec with the perimeter bolt adapters for the valve covers... Hmmm. Those are quite a bit more pricey than the Gen 1s, but great little stump pullers.

Anyway - does anyone know the difference in the details of the 195 and 260 hp GM Gen 1 crate engines? Thanks!

[Chilly178]

I have narrowed down to two engines, the L31-R or the newer SP350/357. I just don’t know how well the SP350/357 would work in a heavy 3/4 ton geared low. And I’m worried that the L31-R won’t have enough horses for me.

[geezer#99]

THe only difference Jocko is the 260 hp one is because of a 4bbl (holley or eddy) and headers and likely intake.. THey assume you'll outfit the 195 hp one with a stock intake, carb (quadrajet or 2gc) and single exhaust.
http://www.jegs.com/p/Chevrolet-Perf...67244/10002/-1
At least that crate has a cam that's matched closer to it's compression ratio.
The 290 hp engine has a mismatched cam with it's low compression. Look at this chart to see a relationship between cams and compression ratios.
http://www.crankshaftcoalition.com/w..._compatibility

[geezer#99]

Originally Posted by Chilly178

I have narrowed down to two engines, the L31-R or the newer SP350/357. I just don’t know how well the SP350/357 would work in a heavy 3/4 ton geared low. And I’m worried that the L31-R won’t have enough horses for me.

How do you intend to use these motors.
Cruising around town or down the highway.
Either one of those would work great if you don't mind winding the rpm up a little higher.
Just remember if you're producing higher hp you're loosing bottom end hp and torque. Everything moves up the scale.

[truckster]

Originally Posted by Chilly178

I have narrowed down to two engines, the L31-R or the newer SP350/357. I just don’t know how well the SP350/357 would work in a heavy 3/4 ton geared low. And I’m worried that the L31-R won’t have enough horses for me.

One of the car magazines built an engine just like mine - L31, Quadrajet, rams horns, HEI, HT 383 cam - and ran it on a dyno for 330 HP and just shy of 400 ft-lbs torque - and their engine featured a bottom end that was used and not rebuilt. So if you compare it to the 290 HP motor you mentioned in your original post, you've got way more HP, tons more torque, and more importantly, the HP and torque are available across a much broader power band.

[68Stepbed]

For a 3/4 ton, I'd get this hoss!!
http://www.jegs.com/p/Chevrolet-Perf...69813/10002/-1

[jocko]

Originally Posted by geezer#99

THe only difference Jocko is the 260 hp one is because of a 4bbl (holley or eddy) and headers and likely intake.. THey assume you'll outfit the 195 hp one with a stock intake, carb (quadrajet or 2gc) and single exhaust.
http://www.jegs.com/p/Chevrolet-Perf...67244/10002/-1
At least that crate has a cam that's matched closer to it's compression ratio.
The 290 hp engine has a mismatched cam with it's low compression. Look at this chart to see a relationship between cams and compression ratios.
http://www.crankshaftcoalition.com/w..._compatibility

Thx Geezer, so the engines being sold are identical, just advertised differently based on what the buyer adds on - thanks, appreciate the info. Yeah, the compression ratio/cam combo on the 290 horse motor baffles me. I think the 195/260 with a cam improvement may be the way to go (for me) I’d rather change the cam than pistons, ha.

Anyone have any additional info on the internal/external balanced 1 piece rear seal approach? There are a lot of 383 crates floating around ought there so it can’t be that big of an issue - I just haven’t looked into it much yet. I guess I’m only used to internally balanced engines, even though GM has had fully external balanced engines around for decades. I’m guessing it’s just not really a big deal. And if that’s the case then maybe a 383 in sheep’s clothing (stock valve covers with perimeter hold down adapters) is what I am really seeking. If I didn’t care about the bone stock look, I wouldn’t care about the vortec valve cover look.

[truckster]

A 1-piece rear main seal requires a different flywheel or flexplate (different center diameter) and that will be balanced for the 1-piece seal crankshaft - it has a weight on it and it's indexed with a pin so you can't put it on wrong. It's really no big deal.

I can't imagine why you'd want to go with a flat tappet cam when you can get the L31 Vortec with a roller cam and better heads for less money - by the time you add the intake manifold and fuel pump you'll still be money ahead. Read through the forums and you'll find a lot of people who complain about wiped cams, but not a single one with a roller cam. Plus the roller generally has a better profile because it opens and closes quicker.

You can get adapters for perimeter bolt valve covers for Vortec heads, but I like having valve covers that don't leak.

[67ChevyRedneck]

Originally Posted by geezer#99

THe only difference Jocko is the 260 hp one is because of a 4bbl (holley or eddy) and headers and likely intake.. THey assume you'll outfit the 195 hp one with a stock intake, carb (quadrajet or 2gc) and single exhaust.
http://www.jegs.com/p/Chevrolet-Perf...67244/10002/-1
At least that crate has a cam that's matched closer to it's compression ratio.
The 290 hp engine has a mismatched cam with it's low compression. Look at this chart to see a relationship between cams and compression ratios.
http://www.crankshaftcoalition.com/w..._compatibility

I've read a lot of these threads before and a lot of people have been happier with the lower HP version because it appears the "performance version" wasn't optimized for performance at all and has most of it's usable HP in high rpm range. I want my power down low. It's a 4K lb brick.

[jocko]

Originally Posted by truckster

A 1-piece rear main seal requires a different flywheel or flexplate (different center diameter) and that will be balanced for the 1-piece seal crankshaft - it has a weight on it and it's indexed with a pin so you can't put it on wrong. It's really no big deal.

I can't imagine why you'd want to go with a flat tappet cam when you can get the L31 Vortec with a roller cam and better heads for less money - by the time you add the intake manifold and fuel pump you'll still be money ahead. Read through the forums and you'll find a lot of people who complain about wiped cams, but not a single one with a roller cam. Plus the roller generally has a better profile because it opens and closes quicker.

You can get adapters for perimeter bolt valve covers for Vortec heads, but I like having valve covers that don't leak.

Copy on the flexplate, didn't realize they came with an index, so that solves that, thank you. But I don't think you can put a pre-Vortec intake manifold on the L31 can you?

[jocko]

Originally Posted by 67ChevyRedneck

I've read a lot of these threads before and a lot of people have been happier with the lower HP version because it appears the "performance version" wasn't optimized for performance at all and has most of it's usable HP in high rpm range. I want my power down low. It's a 4K lb brick.

Thanks Jesse - I recall reading the same on here and that's why I dug into some of the details on my own. Great info on this forum - and some of the sites, Jegs, Summit, GM, etc all have helpful info if you piece it together by looked at them all. If I go with a pre-vortec, I will likely go with the 195/260 block.

[truckster]

Originally Posted by jocko

Copy on the flexplate, didn't realize they came with an index, so that solves that, thank you. But I don't think you can put a pre-Vortec intake manifold on the L31 can you?

Nope, that's why I said he'd need a new intake. The Vortec heads use an intake with 8 bolts, and the bolts are vertical rather than angled into the head.

[garyd1961]

Originally Posted by Chilly178

I have narrowed down to two engines, the L31-R or the newer SP350/357. I just don’t know how well the SP350/357 would work in a heavy 3/4 ton geared low. And I’m worried that the L31-R won’t have enough horses for me.

The only difference in these motors is the cam and the L31-R is half the price. The L31-R is a 3/4 ton motor and has the torque to move your truck. If you really have to have the extra HP just do a cam swap but I think you will be surprised at the power of the L31-R with a 4 barrel carb and good exhaust.

[jocko]

Thanks Truckster, yes, familiar with the vortec manifold vertical bolts - that's part of my dilemma, wanting to use an original manifold. Missed where you said he'd need a manifold, sorry about that. All on the same sheet of music.

350/357 aside - if I go away from a Gen 1 head config, I'd either go with the L31 or a 383, your point is a good one. In that case it comes down to money, and if tight, L31 a great option.