Low Mileage SBC Minor Rebuild: What to do?

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Low Mileage SBC Minor Rebuild: What to do?

Post by NewbVetteGuy » Wed Oct 10, 2018 12:14 pm

Context: I've got a 40-year-old L82 SBC 350. I planned to just put a new roller cam, heads, and intake into and do an EFI conversion, but I've pulled the block and I think the time is right to ensure that the bottom-end is in good shape.

I'm just not sure what my priorities should be as I haven't seen much discussion on blocks with such low mileage. There's VERY little wear; the bores look great, even the tappets were barely worn. I've got forged pistons and a forged crank so no need, nor desire to replace pistons or bore the block.

Laser-focused question: If rebuilding a stock 350 L82 with low mileage and wear what machining procedures should be done and what parts should be replaced / upgraded?

Engine Build Details: Profiler 195cc heads, aggressive Mike Jone Hyd Roller 227@0.050"; long-runner TPI-style EFI intake, 440 hp @6,000 RPM/ 460 ft lbs @ 4,500 RPM (EA simulation); 10.2:1 CR; SBC 350, L82 (4 bolt mains). Given that I have forged pistons and a forged crank and a Holley EFI, I'd love to be able to spray a 125 HP NOS shot, if desired, too.

I'd love to make upgrades / perform operations that are a good "Bang for the buck"; the fewer machining operations, the better, as far as I'm concerned. (When the bottom end needs refreshed in the future I'll go with a stroker kit and have major machining done, but not today.)


Specific Questions:
  • New Rings?: Are new ring materials significantly improved enough that I should get new piston rings?
    -I called Total Seal yesterday to see what it would cost to get a modern LS-like ring pack and spacers on my old L82 5/64, 5/64, 3/16 and they quoted $490.11; WAY too much $$ for 6 HP @ 6,000 RPM.
  • Decking the block / squaring the block: I've heard from some threads here on ST that these old SBCs are notorious for having uneven / unsquare decks. I'd obviously like to have more consistent CR and Piston-to-head clearance cylinder to cylinder. But I REALLY want to maintain my #s on my #s matching block and I don't want to
    dramatically increase the CR.
  • Rod Bolt / Mains Bolts Upgrades I've heard that one of the weaker links in these old SBCs is the stock rod bolts and mains bolts. ARP advertises a 2x - 4x improvement in strength over stock bolts. My understanding is that studs could significantly increase the load on the rods/mains and if going with a mains studs upgrade I should have the mains honed. -My question then becomes whether just upgrading to a high quality ARP mains BOLT also necessitates checking for roundness or honing or not.
  • Freeze Plugs: Should I have the freeze plugs replaced for some reason?
  • Crank Bearings: My understanding is that crank bearings get worn primarily based upon mileage and RPM and I probably don't need to worry here.
  • Rear Main Seal: Oil leaks are evil; replacing rear main seals with the block in the car SUCKS, I should put a new Felpro gasket on while the block is out. -My thought, anyway.

What else?



Adam

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Re: Low Mileage SBC Minor Rebuild: What to do?

Post by F-BIRD'88 » Wed Oct 10, 2018 3:25 pm

The long runner tpi intake is a mistake.
Use a weiand stealth ram efi intake. If you want a real 440 hp from that 350.

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Re: Low Mileage SBC Minor Rebuild: What to do?

Post by CGT » Wed Oct 10, 2018 4:35 pm

NewbVetteGuy wrote:
Wed Oct 10, 2018 12:14 pm
Context: I've got a 40-year-old L82 SBC 350. I planned to just put a new roller cam, heads, and intake into and do an EFI conversion, but I've pulled the block and I think the time is right to ensure that the bottom-end is in good shape.

I'm just not sure what my priorities should be as I haven't seen much discussion on blocks with such low mileage. There's VERY little wear; the bores look great, even the tappets were barely worn. I've got forged pistons and a forged crank so no need, nor desire to replace pistons or bore the block.

Laser-focused question: If rebuilding a stock 350 L82 with low mileage and wear what machining procedures should be done and what parts should be replaced / upgraded?

Engine Build Details: Profiler 195cc heads, aggressive Mike Jone Hyd Roller 227@0.050"; long-runner TPI-style EFI intake, 440 hp @6,000 RPM/ 460 ft lbs @ 4,500 RPM (EA simulation); 10.2:1 CR; SBC 350, L82 (4 bolt mains). Given that I have forged pistons and a forged crank and a Holley EFI, I'd love to be able to spray a 125 HP NOS shot, if desired, too.

I'd love to make upgrades / perform operations that are a good "Bang for the buck"; the fewer machining operations, the better, as far as I'm concerned. (When the bottom end needs refreshed in the future I'll go with a stroker kit and have major machining done, but not today.)


Specific Questions:
  • New Rings?: Are new ring materials significantly improved enough that I should get new piston rings?
    -I called Total Seal yesterday to see what it would cost to get a modern LS-like ring pack and spacers on my old L82 5/64, 5/64, 3/16 and they quoted $490.11; WAY too much $$ for 6 HP @ 6,000 RPM.
  • Decking the block / squaring the block: I've heard from some threads here on ST that these old SBCs are notorious for having uneven / unsquare decks. I'd obviously like to have more consistent CR and Piston-to-head clearance cylinder to cylinder. But I REALLY want to maintain my #s on my #s matching block and I don't want to
    dramatically increase the CR.
  • Rod Bolt / Mains Bolts Upgrades I've heard that one of the weaker links in these old SBCs is the stock rod bolts and mains bolts. ARP advertises a 2x - 4x improvement in strength over stock bolts. My understanding is that studs could significantly increase the load on the rods/mains and if going with a mains studs upgrade I should have the mains honed. -My question then becomes whether just upgrading to a high quality ARP mains BOLT also necessitates checking for roundness or honing or not.
  • Freeze Plugs: Should I have the freeze plugs replaced for some reason?
  • Crank Bearings: My understanding is that crank bearings get worn primarily based upon mileage and RPM and I probably don't need to worry here.
  • Rear Main Seal: Oil leaks are evil; replacing rear main seals with the block in the car SUCKS, I should put a new Felpro gasket on while the block is out. -My thought, anyway.

What else?



Adam
Id do all of the above. Factory machining during that period is generally very very poor, so no wear means little to me. I'd have a hard time putting something together without square decks, round cylinders etc. It needs it all, and would get it all if I was involved. Considering reusing bearings, rings, freeze plugs etc is just silly in my opinion...considering the cost and availability of those parts, along with having a chance of making things "right"
"How or Y do you think I get all this $hit, I read all of you all builds and desktop dyno them with all the correct info and I've got your build."

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Re: Low Mileage SBC Minor Rebuild: What to do?

Post by NewbVetteGuy » Wed Oct 10, 2018 4:57 pm

F-BIRD'88 wrote:
Wed Oct 10, 2018 3:25 pm
The long runner tpi intake is a mistake.
Use a weiand stealth ram efi intake. If you want a real 440 hp from that 350.
It's not a GM TPI intake...
Image

1.75" stock ID (compared to 1.4"? 1.6"? for the GM TPI intake), 19.25" total runner length from entry to valve (compared to 22" for the TPI). 835 CFM throttle body. 296 CFM as-cast on the weakest runner (over 300 CFM on the rest; according to BigJoe's flow bench with someone else's FIRST intake); way bigger plenum and way better entries from the intake to the head. Mine has been ported 2 sizes larger to a Felpro 1206.

Pipemax estimates that for a 350 with 5.7" rods and my intake (out-of-box) the 2nd Harmonic tuned length is 18.96"; my actual total runner length is 19.25" and the last probably 3rd of the runner has been opened up bigger than stock, which should move the tuned rpm up a little bit, so the intake is almost a PERFECT match.


RCS sells a crate 383 with this intake that makes 520 ft lbs @ 4,000 RPMs and 460 HP @ 5,200 RPM on 93 octane on 10.1 CR. I've got Profiler 195cc heads and what I'm guessing is a little bit bigger and more aggressive Mike Jones roller cam with an estimated torque peak +500 rpm and HP peak +600 RPM (yes, I'm missing 33 cubic inches and some piston speed) http://rcsracingengines.com/Perf%20Crat ... 20EFI.html

My engine was modeled using EA Pro by BadSS on 3rd Gen; those guys over there are very familiar with this intake and have a number of cars that have been on the dyno. If EA Pro with good data says 440hp, I figure it's ballpark close enough.


My goals are as much torque as possible and an HP peak of 6,000 RPM. I think the top-end is pretty well matched towards that goal.

Have any recommendations on the bottom-end? (The top end is already purchased.)

Adam

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Re: Low Mileage SBC Minor Rebuild: What to do?

Post by NewbVetteGuy » Wed Oct 10, 2018 5:11 pm

CGT wrote:
Wed Oct 10, 2018 4:35 pm
NewbVetteGuy wrote:
Wed Oct 10, 2018 12:14 pm
Context: I've got a 40-year-old L82 SBC 350. I planned to just put a new roller cam, heads, and intake into and do an EFI conversion, but I've pulled the block and I think the time is right to ensure that the bottom-end is in good shape.

I'm just not sure what my priorities should be as I haven't seen much discussion on blocks with such low mileage. There's VERY little wear; the bores look great, even the tappets were barely worn. I've got forged pistons and a forged crank so no need, nor desire to replace pistons or bore the block.

Laser-focused question: If rebuilding a stock 350 L82 with low mileage and wear what machining procedures should be done and what parts should be replaced / upgraded?

Engine Build Details: Profiler 195cc heads, aggressive Mike Jone Hyd Roller 227@0.050"; long-runner TPI-style EFI intake, 440 hp @6,000 RPM/ 460 ft lbs @ 4,500 RPM (EA simulation); 10.2:1 CR; SBC 350, L82 (4 bolt mains). Given that I have forged pistons and a forged crank and a Holley EFI, I'd love to be able to spray a 125 HP NOS shot, if desired, too.

I'd love to make upgrades / perform operations that are a good "Bang for the buck"; the fewer machining operations, the better, as far as I'm concerned. (When the bottom end needs refreshed in the future I'll go with a stroker kit and have major machining done, but not today.)


Specific Questions:
  • New Rings?: Are new ring materials significantly improved enough that I should get new piston rings?
    -I called Total Seal yesterday to see what it would cost to get a modern LS-like ring pack and spacers on my old L82 5/64, 5/64, 3/16 and they quoted $490.11; WAY too much $$ for 6 HP @ 6,000 RPM.
  • Decking the block / squaring the block: I've heard from some threads here on ST that these old SBCs are notorious for having uneven / unsquare decks. I'd obviously like to have more consistent CR and Piston-to-head clearance cylinder to cylinder. But I REALLY want to maintain my #s on my #s matching block and I don't want to
    dramatically increase the CR.
  • Rod Bolt / Mains Bolts Upgrades I've heard that one of the weaker links in these old SBCs is the stock rod bolts and mains bolts. ARP advertises a 2x - 4x improvement in strength over stock bolts. My understanding is that studs could significantly increase the load on the rods/mains and if going with a mains studs upgrade I should have the mains honed. -My question then becomes whether just upgrading to a high quality ARP mains BOLT also necessitates checking for roundness or honing or not.
  • Freeze Plugs: Should I have the freeze plugs replaced for some reason?
  • Crank Bearings: My understanding is that crank bearings get worn primarily based upon mileage and RPM and I probably don't need to worry here.
  • Rear Main Seal: Oil leaks are evil; replacing rear main seals with the block in the car SUCKS, I should put a new Felpro gasket on while the block is out. -My thought, anyway.

What else?



Adam
Id do all of the above. Factory machining during that period is generally very very poor, so no wear means little to me. I'd have a hard time putting something together without square decks, round cylinders etc. It needs it all, and would get it all if I was involved. Considering reusing bearings, rings, freeze plugs etc is just silly in my opinion...considering the cost and availability of those parts, along with having a chance of making things "right"


Thanks, am I forgetting anything?

-Any recommendations on what to do about the rings? Is a Moly ring ok with a little 125 NOS shot? (assume so, but assuming is dangerous)


Adam

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Re: Low Mileage SBC Minor Rebuild: What to do?

Post by F-BIRD'88 » Wed Oct 10, 2018 5:39 pm

If you want the torque and power of a 383, build a 383.
A cast hyper piston cast stroker crank 383 kit is fine for this. (Scat)

Put that 350/short block aside.

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Re: Low Mileage SBC Minor Rebuild: What to do?

Post by cgarb » Thu Oct 11, 2018 12:08 am

Is there a budget you wish to adhere to? Now is the time to make things right you know. If you want to get things round square and flat. Better pistons with the thinner rings would be worth some HP, just having stuff round and true is worth a few HP. If your doing stuff on the cheap, yeah berry brush hone and a set of decent quality rings would make it NOS worthy, in small doses. If you don't have a spending limit, a nice 383 assembly and some block blueprinting work would make for a nice little torque monster.

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Re: Low Mileage SBC Minor Rebuild: What to do?

Post by Schurkey » Thu Oct 11, 2018 1:14 am

Put the original engine in a bigass plastic bag. Oil the cylinders and the original stampings on the deck surface. Vacuum the air out of the bag just after tossing in a few desiccant packs, and tie the bag SECURELY shut. Stuff it under the workbench in your garage for "later".

Build or buy the 383 you actually want.

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Re: Low Mileage SBC Minor Rebuild: What to do?

Post by rebelrouser » Thu Oct 11, 2018 8:50 am

Adam, I teach engine rebuilding, this is what I tell my students, locate the specifications for the engine, measure and inspect each component, after you compare your measurements with the specifications for each piece of the engine, you decide to use the component as it is, have it repaired or rebuilt, or you replace it with a new one. All the things you mentioned in your post can be measured and compared to specifications. Many shops replace things like rings and bearing, oil pumps, with every rebuild. Some states have laws about what a shop to replace to sell the job as a rebuild. If you are doing the work yourself it is your decision.

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Re: Low Mileage SBC Minor Rebuild: What to do?

Post by psychomotors » Thu Oct 11, 2018 11:24 am

Schurkey wrote:
Thu Oct 11, 2018 1:14 am
Put the original engine in a bigass plastic bag. Oil the cylinders and the original stampings on the deck surface. Vacuum the air out of the bag just after tossing in a few desiccant packs, and tie the bag SECURELY shut. Stuff it under the workbench in your garage for "later".

Build or buy the 383 you actually want.
Opinions are like belly buttons , but this is my thought also.
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Re: Low Mileage SBC Minor Rebuild: What to do?

Post by Frankshaft » Thu Oct 11, 2018 11:28 am

I can tell you one thing. It will never peak at 6000 with that intake. 5000 is more in line where it will peak.

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Re: Low Mileage SBC Minor Rebuild: What to do?

Post by midnightbluS10 » Thu Oct 11, 2018 11:31 am

Schurkey wrote:
Thu Oct 11, 2018 1:14 am
Put the original engine in a bigass plastic bag. Oil the cylinders and the original stampings on the deck surface. Vacuum the air out of the bag just after tossing in a few desiccant packs, and tie the bag SECURELY shut. Stuff it under the workbench in your garage for "later".

Build or buy the 383 you actually want.
They sell oxygen absorbers on Amazon, also. They do work. Not sure how they work with engines as I haven't used any yet but it couldn't hurt to try. They're just bags of some sort of desiccant, also.
JC - Precision Guesswork & Expert Up Arrow Manipulation

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Re: Low Mileage SBC Minor Rebuild: What to do?

Post by CGT » Thu Oct 11, 2018 12:52 pm

Whats a L82 350 really worth anyway?...or what it came out of? Not exactly prime muscle car material. I would use it.
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Re: Low Mileage SBC Minor Rebuild: What to do?

Post by Newold1 » Thu Oct 11, 2018 8:47 pm

If your L82 is a Corvette unmolested original L82 in the shape you say it is in with low miles then I agree with others here , clean it up, prep for storage and bag it up for future sale as more and more of those old vettes are being restored and put back to original numbers cars and that can make the old complete engine more valuable for resale than what you will save using the short block for a stretched 350 build.

Put together a nice all forged properly machined and assembled 383 short block and put your heads intake and a "better camshaft" than you mentioned and you can make an easy 450-500HP 6000rpm engine that can take a 125 squirt of nitrous easy. JMHO
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Re: Low Mileage SBC Minor Rebuild: What to do?

Post by Krooser » Fri Oct 12, 2018 9:34 am

Save that engine and build another... I've seen a couple guys do what you are suggesting only to have themselves scared to death of blowing up that numbers matching block.

Buy a core block and go from there. It's likely a good machine shop will have one in stock...
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