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#26 | |
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Join Date: May 2016
Location: Henderson NC
Posts: 975
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Re: What GM create engine to buy for 3/4 ton 72 C20
Quote:
ETA- The center bolt valve covers like the one piece rear main seal don't leak like the old style does. I didn't like the center bolt valve covers at first but now I prefer them over the old valve covers. No need to tell me yours don't leak because everyone knows they leak sooner or later, usually sooner. Last edited by garyd1961; 11-13-2017 at 09:57 PM. |
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#27 | |
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Location: Harrison, Arkansas
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Re: What GM create engine to buy for 3/4 ton 72 C20
Quote:
I too have a negative vibe about center valve cover hold downs. The after market vortec heads we used on the Blazer were dual bolt pattern, so we used original valve covers. We had to redo the exhaust and oil filler tube because of the angle of the heads. The rear AC compressor brace wouldn't work either. The 290 crate motor we used on the K10 worked great as an install. I had all the same emotions about the engines you mentioned. It has a nice lumpy idle and works well. It's not the torq monster we would like but is fine for pulling the boat and atv's.
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other Larry Build thread, Arkansas K10 https://67-72chevytrucks.com/vboard/...=755797&page=5 The ability to speak several languages is an asset, but the ability to keep your mouth shut in any language is priceless. |
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#28 |
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Join Date: May 2016
Location: Green Bay, WI
Posts: 134
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Re: What GM create engine to buy for 3/4 ton 72 C20
Thank you everyone for the feedback! I think I have made up my mind and will go with the L31-R. Some questions I have is what parts I need to make this engine work in the 72. My engine mounts currently in the truck look nasty any suggestions on mounts? Will this bolt up to the SM465 with no issues with the correct(?) flywheel? Another question I have is how the serpentine system would work. My truck doen't have power steering or AC and I intend to keep it that way. It uses a old school simple thin belt setup that only goes to the alternator. Can I keep this simple setup and same alternator or I need to buy a serpentine kit for the L31-R? If I do have to buy a kit do they all come with power steering and AC provisions? What do I do with it? Also I would need a water pump, intake manifold for carb, new carb, exhaust manifold/headers?, HEI distributor, electronic fuel pump, air cleaner, and plugs and wires. Any suggestions or anything I'm missing for this. Also will the starter thats in the 350 in the truck now work with L31-R? Will the radiator be the same? Any additional wiring needed? I also saw somewhere you have to plug a hole in the block for a sensor? Any mods I should make to the L31-R before it goes on for more hp/ torque? Thanks
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#29 |
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Join Date: May 2016
Location: Henderson NC
Posts: 975
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Re: What GM create engine to buy for 3/4 ton 72 C20
You should be able to use the factory style mounts, I did. I also added chains to my motor because I read the mounts are prone to breaking. I have a V-belt setup, I had some old brackets and just matched up some to work. Yours should be easier without power steering. Use a water pump made for your model truck, I have a problem with mine, lower radiator hose hitting the frame. I used the thick Felpro gaskets(forget the part #) for the intake and Edelbrock part #9300 gasket sealer. This is what Edelbrock recommends for their E-Tec heads which is basically the same thing. You will need a new flywheel made for a 1 piece rear main seal. Right now I'm running a Holley Mighty-Mite fuel pump which is pretty quiet. I have only run it for a few weeks but no problem with it yet. The bigger Holley pumps are loud as He!!.The starter should work depending on what exhaust you use. I'm running a mini-starter but don't buy a MSD mini-starter, two different cousins have had 4 to go bad in no time. If low end torque is what you want leave the motor alone and put a low profile duel plane intake (I used a Summit Stage 1) and good exhaust. I used long tube headers and 2 1/2 exhaust.
Just one more thing, If you don't have your heater hooked up be sure to run a by-pass hose from your intake to your water pump. |
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#30 | |
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Location: Orem, Utah
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Re: What GM create engine to buy for 3/4 ton 72 C20
Quote:
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I have sworn upon the altar of God, eternal hostility against every form of tyranny over the mind of man. - Thomas Jefferson |
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#31 |
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Location: Godley, TX
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Re: What GM create engine to buy for 3/4 ton 72 C20
A little more info on the GM crates. Note that the L31 we've been talking about that lists for just a hair over $2000 is the base L31 - but it also has a slightly more expensive brother (I assume this is the L31R some have referenced - it's specified for 3/4 ton and up, whereas the base L31 is considered a 1/2 ton replacement). Anyway, L31R = L31 HD (same engine, just different terminology depending on where you're looking). From what I can see it has the exact same specs, but you get 4 bolt mains for your extra $200. If I were to go the GM crate with vortec heads budget route - either of the L31s is hard to beat bang-for-the-buck-wise. The HT383 has some impressive numbers (but an equally impressive price - more than double an L31).
Here they are: L31 https://sdparts.com/i-19928727-gm-en...te-engine.html L31 HD https://sdparts.com/i-19928425-gm-en...te-engine.html HT 383 https://sdparts.com/i-19928346-chevr...SABEgKvj_D_BwE Some interesting notes: - The L31s have a hyd roller cam/383 has a hyd flat tappet - 383 has a forged crank/L31s are cast - L31s require electric fuel pump (as mentioned above) - 383 includes manifold and ext balanced flexplate (not sure if L31s include a flexplate) - 383 and L31 HD are 4 bolt mains, L31 is not. - L31 CR=9.3:1 / 383 CR=9.1:1 (MUCH better than the 195/290 hp crates' 8.5/8.0:1 CRs) - Both have decent lift cams, 383 is more aggressive, thus the hp delta.. Bottom line, I'm not building a race truck - but the extra 100 ft-lbs of torque of the 383 sure would be nice. However, very best bang for the buck imho is the L31 HD. I think a set of center-to-perimeter bolt valve cover adapters may be in order... ![]() EDIT: Note in the table below for the HT383 cam - it is a mis-print. HT 383 has a hyd roller, not a hyd flat tappet cam. Last edited by jocko; 11-19-2017 at 01:11 AM. |
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#32 |
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Location: Harrison, Arkansas
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Re: What GM create engine to buy for 3/4 ton 72 C20
I have the L31 in my 55 Chevy 210 2 dr. It is a very capable, smooth running little engine, but is a little anemic. It does fine, but the response to the go pedal is a little light to suit me.
The roller cam was the biggest factor in the purchase of the L31, but if I were to do it again, I would gladly pay for more torque and HP. You can build a 383 cheaper than that HT383 and have a roller cam. I love the 383 we have in the Blazer.
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#33 |
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Re: What GM create engine to buy for 3/4 ton 72 C20
Jocko, the HT 383 has a hydraulic roller cam: http://www.chevrolet.com/performance...l-block-ht-383
If you want to save some money but get more HP and torque, buy the HT 383 cam and put it in your L31 block. That will get you close to the 383's numbers - at a much more friendly price.
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#34 |
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Re: What GM create engine to buy for 3/4 ton 72 C20
I have been thinking about calling Comp Cams and ordering a roller cam set up for my L31.
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other Larry Build thread, Arkansas K10 https://67-72chevytrucks.com/vboard/...=755797&page=5 The ability to speak several languages is an asset, but the ability to keep your mouth shut in any language is priceless. |
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#35 |
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Re: What GM create engine to buy for 3/4 ton 72 C20
[QUOTE=truckster;8082963]Jocko, the HT 383 has a hydraulic roller cam: http://www.chevrolet.com/performance...l-block-ht-383
Thanks - that’s certainly what i was expecting, was surprised that Scoggin Dickey listed it as a flat tappet. Ok, scratch that detractor! Good point on 383 cam in the L31. Has anyone does this that can confirm you won’t kiss a piston in the slightly higher compression L31 with the slightly higher lift of the HT383 cam? I highly doubt it, the lift isn’t “that” aggressive, but would be a comforting data point. I’d probably go with the 383’s intake also. Considering GM Parts prices - by the time you add a flexplate, manifold, electric go, and cam, you might be tickling just south of the 383’s price tag, and you could use a mech pump with the 383 ![]() Last edited by jocko; 11-15-2017 at 03:28 PM. |
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#36 | |
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Location: Orem, Utah
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Re: What GM create engine to buy for 3/4 ton 72 C20
[quote=jocko;8083021]
Quote:
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I have sworn upon the altar of God, eternal hostility against every form of tyranny over the mind of man. - Thomas Jefferson |
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#37 |
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Re: What GM create engine to buy for 3/4 ton 72 C20
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#38 |
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Re: What GM create engine to buy for 3/4 ton 72 C20
I want more power, and a 55 Chevy is supposed to have an engine that lopes.
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other Larry Build thread, Arkansas K10 https://67-72chevytrucks.com/vboard/...=755797&page=5 The ability to speak several languages is an asset, but the ability to keep your mouth shut in any language is priceless. |
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#39 |
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Re: What GM create engine to buy for 3/4 ton 72 C20
Ah copy, thanks. Completely understand!
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#40 |
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Re: What GM create engine to buy for 3/4 ton 72 C20
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#41 |
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Join Date: Jul 2015
Location: North East PA
Posts: 682
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Re: What GM create engine to buy for 3/4 ton 72 C20
Yes you will need a plug that will go in to the timing cover because you are deleting the Sensor. you will also need a Melonized gear for your Hei distributor ,because of the hardness of the Cam in the L31 , I think you might want to go with the serpintine set up as the L31 was designed for it and you can go to your local pick n pull yard and get everything you need in a Hours time for around $100 ,if you try to go with your old V/belt set up it will cost you more money to convert and ton of agravation trying to line up the pullys and finding the correct pullys . also serp set up is more reliable ,
I just put a L31 in my 68 a few months back ,So I am just going by my personal experience installing the L31 vortec , So far its a great little engine that is driven everyday |
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#42 |
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Join Date: May 2016
Location: Henderson NC
Posts: 975
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Re: What GM create engine to buy for 3/4 ton 72 C20
Have you checked out Summit? No shipping but I believe there is a $100 core charge. Also you will need a way to unload the motor out the back of a semi if you want it delivered to your house. You may find it a little cheaper but Summit is an A1 company to deal with.
https://www.summitracing.com/parts/nal-12530283 Don't pay any attention to the HP ratings. If you install a 4 barrel carb and good exhaust you will get 300 hp easily but the torque will be way more. Torque is what you want, HP sells cars Torque wins races. |
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#43 |
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Join Date: Nov 2014
Location: Lincoln City DE
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Re: What GM create engine to buy for 3/4 ton 72 C20
depending on the overall gear ratio, horsepower is the most important measure. Because of the math, an engine that is tuned to have peak horsepower below 5252 RPM will ALWAYS have more torque than horsepower, and engines with peak horsepower above 5252 RPM will ALWAYS have more horsepower than torque
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#44 |
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Re: What GM create engine to buy for 3/4 ton 72 C20
Confused yet jocko?
Interestingly, there is not a "wrong" answer in all this. It's all in what you want.
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other Larry Build thread, Arkansas K10 https://67-72chevytrucks.com/vboard/...=755797&page=5 The ability to speak several languages is an asset, but the ability to keep your mouth shut in any language is priceless. |
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#45 |
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Location: Godley, TX
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Re: What GM create engine to buy for 3/4 ton 72 C20
Ha, no not confused. I didn't even start the thread! Ha, hope I haven't butted in too much. The reality of my situation is that my K20 has a pretty raggedy replacement engine in it, couldn't even trace the numbers on it, but am guessing late 70's/early 80's passenger car. I've stumbled onto a no-kidding running 72 350 with all the a/c goodies attached that I could make a deal on - but it has a little over 200k on it with 1 rebuild about 40k mi ago. Nothing wrong with that - I'd get what, to me, would be what I'd have been dealing with when new - just not new. I'm not worried about numbers matching - but I am kind of on the "period correct" bandwagon. Anyway - the availability of the local 72 350 has kinda forced my hand even though I'm nowhere near tearing down the K20 for a rebuild. But - a bird in the hand... I should either crap or get off the pot with this engine. So, it's forced me to think about crates now rather than when I'm ready to install in the future. And, while I enjoy rebuilding old engines, if I went with the 72 350 and redid it, I'd still have a 200k+ motor (and that's ok) but likely with a .060 overbore by the time I'm done. Not too concerned with that, but a brand new crate might be a better approach. Am guessing rebuild of the stock 350 would yield similar #'s to the 195/260/290 Gen 1 crates. nothing to write home about, but a capable driver. Since I intend to stuff a camper on the K20, it would be nice to get a bit more than what the stock 350 (or a crate 290) would provide. Although I really do like the 195 with a cam swap approach. Still, probably not much better than original stock 350.
So, my initial aversion to one piece rear seals and vertical intake bolts has subsided a bit (as long as I use the perimeter valve cover bolt adapters). I really think it will come down to either the HT383 (if times are good) or the L31 HD (if things are just what they are today). I'd be happy with either. All said and done, it's really only about a $1K-1300 difference once you add in the flexplate, fuel pump, intake, etc. So, would I spend that for an extra 100+ lb ft of torque. Hmm. Maybe! ![]() Appreciate all the insight from those that have installed either of these engines - very helpful. I'm gonna think on it a little bit longer and perhaps let my procrastination on the 200k mi 350 make the decision for me ![]() EDIT: Thanks Gary - yes, I have checked out summit - was just posting specs from GM sites. Summit is where I go first to buy IF they have it - they tend to have the best prices. They beat Scoggin Dickey by almost $200 on the L31R. And, they just opened a store in Arlington, a hop skip and a jump from my house ![]() Last edited by jocko; 11-16-2017 at 12:08 AM. |
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#46 |
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Re: What GM create engine to buy for 3/4 ton 72 C20
I lost track of the OP. Sorry Gary.
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other Larry Build thread, Arkansas K10 https://67-72chevytrucks.com/vboard/...=755797&page=5 The ability to speak several languages is an asset, but the ability to keep your mouth shut in any language is priceless. |
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#47 |
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Re: What GM create engine to buy for 3/4 ton 72 C20
Honestly, in a truck, when was the last time you spun an engine up past 5k to get max horsepower?. Very rarely if any of my engines see even 4k with a manual trans.
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#48 |
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Re: What GM create engine to buy for 3/4 ton 72 C20
Best price I've found on the L31 R: $1971
https://www.ebay.com/itm/GM-OEM-NEW-...BYyYeE&vxp=mtr |
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#49 |
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Join Date: May 2016
Location: Green Bay, WI
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Re: What GM create engine to buy for 3/4 ton 72 C20
Yeah I tend to agree with you jocko. L31-R or the HT383 I think are the best options for low end torque, vortec heads, and hydraulic rollers. It’ll just boil down to how much you got to spend.
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#50 | |
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Re: What GM create engine to buy for 3/4 ton 72 C20
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