When you click on links to various merchants on this site and make a purchase, this can result in this site earning a commission. Affiliate programs and affiliations include, but are not limited to, the eBay Partner Network.
Just going to mention you will want to save that old c3 specific oil pan off that engine to bolt on to your new engine regardless wich means you need to set the oil pump pickup for the the old pan also regular pans hit the c3 power steering ram and hang lower. If this was my situation id pull things apart since youve decided to pull the engine. I'd at least replace the timing chain and maybe consider a ball hone and re ringing it though thats not needed by the compression readings. Id replace the main seal and oil pan gasket with the silicone/rubber type and take a quick peak at the mains bearing while in there just for piece of mind. (again not needed) a 4 bolt has no advantage for your stated application, dont get sidetracked into something you dont need or want. A lot of folks (myself included) are giving advice based off our own choices or priorities.
Last edited by augiedoggy; Feb 16, 2026 at 08:51 AM.
The Flotek heads are inexpensive and a good upgrade so I would just automatically chuck them.
After rereading my post I meant to say "The Flotek heads are inexpensive and a good upgrade so I would just automatically chuck the cast iron heads".
I agree with Augiedoggy on the two bolt main being strong enough and if you want to give a quick freshening up with a ball hone, some new rings and bearings that's a good idea too. I just wouldn't go dumping thousands of dollars into that block.
I would advise the hard stone hone. You can see if the bores are straight and where the low spots are. You need only remove what you must remove based on the witness marks. The ball hone will rough up a smooth bore for new rings but if the taper is excessive, you will never know about it.
The old heads would go right in the trash IMO. The original heads will need a full valve job and they do not improve anything. They were crack prone even when new. I had one replaced with a later casting date on my '80 before I got the car with just 43K on the odometer. Get an estimate from the machinist to do the valve job before you make the decision. New heads will look pretty good from a cost and performance perspective.
You may have had a bad experience ( have yet to actually find any threads with data on these failures here but lots of warning to stay away because they are cheap and chinese) Maybe you can share what was wrong with the unit you had issues with to help the rest of us understand what to look for?
Theres a lot of us who stabbed a $50 HEI off amazon or ebay in and had zero issues also. I needed the tach drive and replaced my points distributor when I swapped engine 14 years ago. I did tune the curve by changing the springs and adjusting the vac can but you want to do that with a stock hei as well. I pulled the hei to put a melonized gear a few years back when I swapped in a comp roller cam and there was no additional play or wear issues I did a little research and found there are at least 2 different chinese manufacturers selling online and they sell the same units as summit and jegs brand and others. I have a new accel non tach drive HEI and thats also a generic chinese clone just branded and sold by Holley/ accel. Again Im not stating these are all fine with no issues but I did look for more data and searched this forum as well as other hot rod forums and found all but one of the mentions of issues I read about were anecdotal third party or from folks who had no idea how to change springs or weights or adjust the allen screw in the vac can to make the curve work with their engine configuration. these arent a bolt on and go with best results thing.
The one thread I did find with actual first hand reports of issues from chinese HEIs was from a guy who had a side business rebuilding OEM heis so theres kinda a bias and conflict of interest when they were costing him business.
Im no crusader for chinese good but I Do like to research and know when I do buy something due to budget if its actually poor quality and /or if its the same stuff being rebranded and sold under the big performance part brand umbrellas for much more $$ So often with car parts its all about the marketing and not so much who and where its made anymore. case in point are the head castings... Many are chinese now and the same castings are rebranded and sold at drastically different prices. cam shafts and lifters are another area where only a few manufacturers make and sell to all the other brands (if those brands arent already a sister company like edelbrock/comp/lunati and the like.)
Mechanically the HEI units are great, it's the aftermaket Ignition modules that tend to fail intermittently. Failures due to heat related issues. They work fine when cold, but as they heat up things expand like printed circuit boards and cause poor connectivity between components or the components themselves. Never opened up an ignition module as they are sealed units and would be trashed if you could. I am just summarizing or for lack of a better word theorizing here as to the failure issues.
Yeah, I guess I got a bit disgusted with how dirty the outside of the block was yesterday trying to clean it. Going to try and clean it with something different today. The oil pan I can blast the outside to bare metal in my blast cabinet and prime and paint it to look like new.
After rereading my post I meant to say "The Flotek heads are inexpensive and a good upgrade so I would just automatically chuck the cast iron heads".
I agree with Augiedoggy on the two bolt main being strong enough and if you want to give a quick freshening up with a ball hone, some new rings and bearings that's a good idea too. I just wouldn't go dumping thousands of dollars into that block.
Yeah, I don't want to dump a lot of money in the L83 block. I can still see the cross hatch from the honing and can't measure any taper in the bore but a set of bearings and check the ring gap is a good idea... hopefully Bubba didn't rebuild the short block.
JT
Last edited by jthornton; Feb 16, 2026 at 03:17 PM.
I would advise the hard stone hone. You can see if the bores are straight and where the low spots are. You need only remove what you must remove based on the witness marks. The ball hone will rough up a smooth bore for new rings but if the taper is excessive, you will never know about it.
The old heads would go right in the trash IMO. The original heads will need a full valve job and they do not improve anything. They were crack prone even when new. I had one replaced with a later casting date on my '80 before I got the car with just 43K on the odometer. Get an estimate from the machinist to do the valve job before you make the decision. New heads will look pretty good from a cost and performance perspective.
good point I prefer the stone hone also but the dingle ball version is the one that always seems to be the fav here which was why I had mentioned it.
Ok, I'm feeling better about getting the outside of the block clean. I'll just take my time and get it clean then take the oil pan, harmonic balancer and timing chain cover off and take a peek inside.
If it was mine, I would pull all the core plugs out and remove all the pipe plugs too. Then run a thread chaser thru ALL the block threads. You want to clean all the threads before you take it to the shop. Makes your job easier when it comes back.
If it was mine, I would pull all the core plugs out and remove all the pipe plugs too. Then run a thread chaser thru ALL the block threads. You want to clean all the threads before you take it to the shop. Makes your job easier when it comes back.
By "core plugs" do you mean the freeze plugs? I have a set of thread cleaner things I'll clean all the threaded holes with.
there is a "hidden plug" (either a solid steel ball or barrel shape) that's press-fit driven into a vertical oil gallery. Just Above #5 main cap.
Even with #5 cap removed, it's not obvious. With motor inverted on stand & cap removed, it's another inch or two down in that hole in block. If it is removed for proper cleaning, It MUST be replaced and properly repositioned. Oftentimes, machine shops knock em out for cleaning but often leave their replacement to builder, Who might not KNOW a thing about it (bad).
Its proper vertical location is critical to proper oil circulation. If not properly positioned, you'll Never maintain stable oil pressure and will be WTH wringing hands until ya fix it. Easy to overlook, but PITA to identify & affect a cure once motor's put back into service.
* once more---suggest bake n blast block & iron heads & iron intake Because their coolant passages are surely fouled & coated with 50 years of scale & sediment. Pressure washer & green or purple liquids cannot cut it.
Last edited by Rebelyell; Feb 16, 2026 at 09:21 PM.
there is a "hidden plug" (either a solid steel ball or barrel shape) that's press-fit driven into a vertical oil gallery. Just Above #5 main cap.
Even with #5 cap removed, it's not obvious. With motor inverted on stand & cap removed, it's another inch or two down in that hole in block. If it is removed for proper cleaning, It MUST be replaced and properly repositioned. Oftentimes, machine shops knock em out for cleaning but often leave their replacement to builder, Who might not KNOW a thing about it (bad).
Its proper vertical location is critical to proper oil circulation. If not properly positioned, you'll Never maintain stable oil pressure and will be WTH wringing hands until ya fix it. Easy to overlook, but PITA to identify & affect a cure once motor's put back into service.
* once more---suggest bake n blast block & iron heads & iron intake Because their coolant passages are surely fouled & coated with 50 years of scale & sediment. Pressure washer & green or purple liquids cannot cut it.
Thanks for the heads up on that plug, I didn't see any mention of it in the service manual.
I do need to get it clean enough to disassemble before taking it to the engine shop for cleaning otherwise I'll get covered in nasty greasy dirty oil. Looks like we are down to one automotive machine shop here now.
But my engine is only 44 years old it can't be that bad LOL.
I was surprised at how much oil was still in the engine after letting it drain for two days, more than a cup full came out when I rolled it over. Then I had to roll it back upright to empty the oil in #7 piston and I'm letting it drain for a while.
The oil pan bolts were not tight at all and not even the correct type (socket head cap screws) so no wonder it leaked. The bottom of the oil pan has some black goo in it, that could be the reason the oil went black so quick.
And last photo for today is the oil pressure nipple, is that a pipe thread? Does it screw out? I don't like the looks of that one with the hole way off center.
The chain does have slack but any chain is going to have slack after some time. Yours isn't terrible but you going to replace it anyway.
Oil pan, I've seen worse.
Yes, it should be a pipe thread. Run pipe tap through it loaded with grease to catch shavings to clean it up.
And last photo for today is the oil pressure nipple, is that a pipe thread? Does it screw out? I don't like the looks of that one with the hole way off center.
? Is there a short windage tray attached via main cap bolts ?
Originally Posted by jthornton
And last photo for today is the oil pressure nipple, is that a pipe thread? Does it screw out? I don't like the looks of that one with the hole way off center.
JT
? Is there a short windage tray attached via main cap bolts ?
That oil gallery, with the wonky nipple, pretty sure that's the gallery with the 'hidden plug' located about an inch or so up, from Bottom of that hole.
First --- Measure WHERE it is located; Both from top AND from bottom.
Then, To remove 'hidden plug':
Remove #5 cap.
Remove wonky nipple
From top: insert rod (about 2 ft long) into top
drive 'hidden plug' out bottom
after thorough block cleaning, drive 'hidden plug' into position From Bottom.
That looks a lot like a GM-aftermarket replacement double row timing set; and budget-grade as well. 58 links = small pitch (perhaps roller OD about 0.222" as well). No need for (monkey see-monkey do) a double row anyway. And, a larger pitch double row will likely require grinding-clearancing behind/around chain. Suggest a Quality, Large pitch, Heavy-Duty (46 links), Single Row chain with seamless aka solid rollers. Good uns' rollers have about 0.333" OD. No block grinding either. Part numbers upon request.
Select tapered thread oil fittings with a jaundiced eye; some are relatively weak pot/white metal castings.
