I just pulled everything off the top end of my engine last weekend and although, I'd love to just put a new cam in this thing and bolt the heads and intake on and go, I probably should pull this 40 year old block and get it checked out and get some basic 40 year maintenance done...

Extra Context: My rear main seal is super leaky and needs replaced, I should replace the stock flywheel as I didn't know to do this while the transmission was out (new build will be about 440 ft lbs and 450-470 ft lbs and I don't want to cut off my own feet if the flywheel explodes; not worth it). The engine has a LOT of carbon in it including little chunks floating around. BUT, the engine only has 14.6k miles on it and really has very VERY little wear.


If I decide to pull the block and send it to a machine shop to have it checked out and do a super basic 40k rebuild; what should I have done / reconditioned / replaced / upgraded? (It's an L82 4 bolt mains 010 block) -Let's assume that the cylinders don't have enough wear to even require any boring or honing.

No Brainer / Definitely Should Do:

• Hot Tank / Basic Cleaning
• General inspection
• Magnaflux / check for cracks
• Repaint block
• New Freeze Plugs
• Replace cam bearings (I have a new roller cam going in and I already bought fancy, coated bearings for it)
• camfer oil drainback holes

Should CONSIDER doing:

• Square the block deck (minimum removal of block deck surface to make it level and flat (find shop that can avoid removing the block #'s)
• Rod bolt upgrade
• mains bolt / stud upgrade
• New Piston Rings -assuming the block doesn't need bored at all and I'm keeping the stock L82 forged pistons (I'd kinda like to use Total Seal's ring groove spacers to go with a thin 1.2mm ring pack....)
• Honing the block's cylinders to a modern speced finish as dictated by the ring MFGR
• Install new crank bearings?!??

If you really want to be OCD you could / should do:

• Line hone crank / cam tunnel (requires new bearings)

I'm not sure which operations fall under "definitely should do", "probably should do" vs. "nice to do" and I'd love some feedback on where you all think these things should land.

Note: If the block needs to be bored bigger and needs new pistons, I'm just doing a modern, top shelf 383 stroker kit; right now I'm trying to explore what a basic rebuild would look like if I can still run the current pistons and crank.


Adam

 

So it sounds like you and I are on slightly different ends of the spectrum when it comes to our cars. In that I have a pretty dang small budget, so alot of "if it ain't broke, don't fix it!". I agree that money no object, a full teardown and inspection is the way to go. But with that low of miles, maybe just do a compression test and leakdown test at home and see how healthy your cylinders seem? You may find out that the piston rings are sealing just fine and then you don't have to invest all that money in a rebuild.

That said, it's also possible you do a leakdown and find out that despite your low mileage, you have low compression or cylidner not able to hold up for the leakdown test simply due to the age of the rings and possibly some of that time not being well oiled.

Basically, I would borrow a compression and leakdown tester from your local auto parts store and give it a shot! If your motor is healthy and you are comfortable with running it that way, you saved yourself quite a bit of cash!

But if you have the money to spare, and the peace of mind of a fresh bottom end is important enough to you to spend it on that, then that is definitely the way to go.

I don't think I told you anything you don't already know, hopefully just reaffirmed what you were already thinking! Personal experience: I did a compression test, found my bottom end was decent, and did the head/cam swap in my garage. Cleaned the head mating surface thoroughly, checked it with a straight edge. I then used copper gasket spray on the .015 shim gasket to help seal any imperfections. I've been running it like that for the last couple years no problem.

 

Engine has no heads. Can't do a leakdown.

On the upside, it CAN be visually inspected now. ;-)



The block needs to come out of the car anyway, so taking it somewhere to get it checked out and get a few things done to it that I don't really want to do to it anyway, so I'm just trying to plan ahead.

I've got random hard bits of carbon floating around the inside of the motor too...


Adam

 

Oh well in that case, assuming the bores look ok, and the deck surface is flat, new piston rings and call it a day! Especially considering you have an L82 you have factory forged pistons, might as well use em.

And then the question I always have to ask, if you are going to have it out and the motor apart..... 383 rotating assembly? This way you are starting with all new components and all the little things that are 40 years old (piston wrist pins, crank bearings, main studs/bolts) will be replaced. You could even sell your forged crank, pistons, and rods for a couple hundred bucks to help pay for it. Just my $.02! You seem like you research and think through your stuff alot before you start it, so I'm sure you have already made the decision to stick with a 350 for good reason, more just curious!

Personally, if I was gonna spend the money to have a machine shop dissassemble, check and possibly bore/hone/deck the block and clean it, I would want to just go ahead and get the extra cubes while it's apart. One of those things I'd rather do now and have the extra power, rather then build the motor and later wish you had the extra cubes.

 

I haven't made a decision yet. This is me trying to do more research on that subject...

My gut feeling is that I probably don't need to do anything major to this block right now, but get it cleaned up and checked out and make any minor changes that I might regret not making while I have it apart. (If the bores are good.) -If there's something wrong and it needs bored, and major machining then I'll just go with a stroker crank and make my wallet feel the pain.


Adam

 

If your going to do that much then go all the way and do it all.... Probably don't need studs.

 

With a really leaking rear main, take a close look at the seal area on the crank. If there's a groove where the seal lip rides, you have 2 choices- find a seal that puts the lip in a different spot on the crank, (there are 3 different seals with the same part number), or replace the crank. If you have the crank out anyway, and measure it, just about anything that is close to the limits can justify a new crank. Just looked-- Ohio Crankshaft has a 383 stroker kit for less than $1000.

 

Skip the studs..if you go there may as well line hone, deck, raise compression etc.
Just have them teardown/inspect go from there. How bad could a 14 mi shortblock be?
If you decide to put pistons in then make sure you put a bigger crank in it too! A 396 tpi would be cool & make crazy torque.

 

 

If your being warned about going past 10.2:1 that should be hint that 'forged' may be a good thing. I'd skip the ring spacers, seems to band-aid-ish….

 

 

you have oem forged pistons and crank. re-ring it and spend the diff on brodix heads...

 

14.6 k miles, and you have visual carbon, I would really look at the heads and valves, perfect time to have them serviced before all the re assembly especially if its a tiny crack somewhere can easiy be missed

 

 

 

Teardown inspect, maybe just a quick refresh will do it.

If anything Get rid of the plastic coupler on the oil pump or nylon timing chain if it has them.
You shouldnt hurt the bottom end even with 6k blasts. Gm steel cranks can take a beating.

Let your machinst know the cam specs, take deck measurements to ensure your CR will be where you want before you button it up, go from there.

 

 

crap, think I just found the source of some spark scatter. Ugh..

well theres the difference. One can break, one probably never will. Dont forget to put it in before you torque that oil pump down.

 

I'm going to come back to this thread again, now that all the context is here.

I appreciate all the feedback so far but I don't really feel like I have anything resembling and answer to the question I actually asked, which is: If rebuilding a stock 350 L82 block with VERY low mileage (assumption: keep the stock forged pistons, & crank; no boring or honing necessary; I can disassemble everything/ almost already have), what machining procedures should be done and what parts should be replaced / upgraded?


Specific questions:

1. Rings: Are new ring materials significantly improved enough that I should probably get new piston rings if I plan to keep this car / engine forever?
2. Decking the block / squaring the block: I keep hearing that these blocks are notorious for not being at all square and each piston having it's own piston to valve clearance and ultimately compression ratio. I REALLY do not want to dramatically alter the CR, nor go to a "0 Deck" and I REALLY do not want to lose my matching #s. Just a minor decking to square things up, even them out, and give a good, flat deck surface.
3. Rod Bolts / Mains Bolts (4 bolt mains): I keep hearing that when it comes to making good power, the stock rod bolts and mains bolts are weak links in these old blocks. ARP advertises like a 2x-4x strength improvement if going with their bolts or studs. Because I have an L82 the mains studs are extra long to support the windage tray and replacing the bolts with ARP studs or bolts that support a windage tray is like $150 just for the stud set... (Rod bolts are cheap).
   • If I replace the rod bolts / mains bolts with newer bolts or studs do I now NEED to have the rods and mains professionally checked for roundness and honed?!? I've read that if going to studs, you definitely SHOULD, not sure if just moving to strong bolts necessitates this additional machining and machine shop labor.
4. Freeze plugs: Should I have the freeze plugs replaced for some reason?
5. New Crank Bearings: I'd honestly love to have a tighter crank and cam bearing clearance so I can run lighter weight, synthetic, modern oil... But are crank bearing something that should be done?

Adam

 

I did all 5 of those items when my L82 motor was out two winters ago. 75K miles but the cylinder walls were somewhat scored from cold, dry starts. Kept the stock crank, rods and pistons, just reconditioned them. It was one of those, well as long as you're there things. Only thing different I wish I had done was roller instead of flat tappet cam and aluminum heads instead of Dart iron. Oh well.