Years ago I watched an old man preparing a bare block for rebuilding and was puzzled when I saw him break out a can of stuff called glyptol. It is the reddish brown coating used on electrical motor windings. After making sure all oils and contaminants were off the block he painted lifter valley, crank area, and the timing chain area with the glyptol. He showed me another engine he had apart for repair and it was nice and clean inside. The stuff is really tough and helps oil drain back to the pan better. It doesn't make the engine run any better but it does help keep oil/carbon residue from sticking everywhere.
Ive used that crappy looking yellow Zinc Cromate primer for the some purpose. Lots of big diesels come from the factory with the same yellow coating inside and I split the case on my 49 John Deere A the other day and it even had it inside it and it was clean as a pin.
painting the inside with Glyptol is an old trick....I guess the youngun's haven't heard about it? I personally don't bother, because I have chevys so I have to work on them all the time and they don't have a chance to get dirty inside
I've never heard of this before, I'll try it out on my next build (which is shaping up to be a 327 small block). Thanks!
That was a '70s racers "trick",probably used even before that. Supposed to help the oil drain back easier. Don't think the serious engine builders bother with it any more.
That, & also, "they" say that it helps to seal up casting junk, mold sand, etc. Personally I find it better to actually pay attention when cleaning the block. I prefer to grind/semi polish the valley & drainback channels (along with all the other oil system mods) ...but it's a royal PITA...my own personal stuff only, not others. I would also add that, unless you are meticulous about cleaning the block with MEK, acetone, etc., that the Glyptal may not stick...looks like it does, but it will flake under heat, flow down to the sump, & end up in the pickup screen. At any rate it's best to let it cure for several days, or use a heat lamp.
They painted the inside of the old Harman Collins dual coil caps with glyptal. Seems the old plastics weren't quite the insulator of the stuff we have today and they had arcing problems through the caps.
Yeah, I remember reading about Glyptol in old hot rod engine building books all the time in the '60s and '70s. It sounded like a good idea back then, but I never actually used it before. I do get a die grinder and smooth off any rough flaky looking casting edges down in the lifter valley, and I smooth up the oil drainage holes because they usually have some rough edges. That probably helps a lot with the drainage, because sometime the drainage holes are half plugged up with casting flash. Sometimes the casting flash is just barely hanging on and just crumbles off. I don't know if "casting flash" is the right word, but I'm talking about that thin crusty cast iron that squeezes out between parts of the sand casting cores. Some engines have a lot of it that flakes out of the insides of the water passages too and you can sometimes grind some of that loose junk out with a die grinder or chip it out with an old screwdriver if it's really thin and flaky. When you tear apart an old sludgy engine, you can see that the sludge really builds up around the crusty areas of casting, especially around rough areas near the drainage holes in the lifter valley and the drainage holes in the cylinder heads. A "tree-shaped" carbide cutter in a die grinder works good for most of those areas to smooth them up.
Most of the heat in an engine is in the heads and bores coating the valley,blocks insides and such honestly does little to increase temps Consider the crap that builds up in the block that insulates as well The other thing this does is keep the sand in the castings from getting to the oil Coating provides some measure of windage meaning hot oil is not retained in the castings I use Rustolum's rusty metal primer..... but brush on..... spray can stuff is a different formula and will fall off
I concur 100% - I'd prefer to grind & partial polish than paint the inside w/something that can flake off...I realize it's been done for years & I'm sure with proper surface prep, there's little concern, but why risk it?
Glyptol was the thing to do back in the day..But as noted above, unless perfectly clean it would flake off and get into the pickup.. The best thing to do is grind and clean up the block as best you can before hot tanking it. Then after it is clean and dry, spray "dry graphite" any place where there is not a gasket surface. the oil will run to the pan asap! Also, its no big deal if the graphite doesent stick perfectly. Make sure you clean up any overspray on the gasket surfaces right away with thinner or brake parts cleaner. If you dont the gasket will slide around and possibly leak. ( dont ask how i know! LOL ) Dave
Just a note: You probably would NOT want dry graphite between the crankshaft bearing halves and the block or main caps, or between the rod bearings and the rods or rod caps. You want good clean metal to metal contact in those places, and graphite might just help towards spinning a bearing.
Been using gyptal for many years . Eastwood has it for sale. Its actually a GE product designed for the rebuilding of inside electric motors. Finish last forever and works great. heres our last one..
I saw an article in a Mopar mag within the last couple years, showing some of the build process by one of the top Hemi S/S engine builders in the nation, and he painted the inside of the block. And you better believe someone building top Hemi super stockers is paying about 30 times more attention to everything he does when building an engine than the rest of us do. I could see the benefits in a race engine...I'd be hard pressed to see them in a daily driver. That'd be like micro finishing the lifters, dry coatings on the pistons, etc. -Brad
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