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.
Gentlemen: I pulled the 383 out of my '61 this past weekend and have it partially torn down. Will mic and measure the cylinders for taper and out of round when I remove the pistons. What I've found so far: all cylinders have hone marks, pretty consistent. No ridge, no visible wear other than slight glaze. #3 cylinder has a rust patch where the ring sat for 20 years against the wall. One of the other cylinders has a crazy cross hatch pattern where somebody went nuts with the ball hone...a coarse one. The marks may or may not hone out. What do you think? My plan is a complete teardown and inspection, and go from there. The good: it has a 1977 Nodular iron 400 crankshaft. The camshaft and lifters are as new condition, as are the pistons (from what I can see). The crankshaft thrust is .004". The engine is super clean inside.
The bad: instead of notching the block to clear the crank, the builder shaved the rods. But not all of the rods. Just the ones that required it. The rust on #3 cylinder may or may not hone out. There is no pitting, just light surface rust, proud of the cylinder wall. I'm thinking that the rings didn't smooth this over might be due to ring damage.
The back story: this engine had sat with a blown head gasket between two cylinders (no water jacket) for over 20 years. It had been run hard and put away wet. The deceased owner's son said the engine had been built in the late '70's-early '80's when the car was being drag raced. This engine ran great after I repaired it in 2015, and great for the past few years. 195 PSI in every hole but with 30% leakdown and a lot of blowby.
I'll know more when I pull the pistons and mic the crank and bores, but what do you gents think about that wild cross-hatch pattern in the one cylinder? I suspect this engine will have either stuck, broken, or worn out piston rings. I'll know soon and post my findings.
Photo 1 shows rust at 1 o'clock. Photo 2 shows crazy hone marks. Photo 3 shows how all the other cylinders look. Photo 4 is another shot of the dingle ball blues....
Wow, glad you are fixing it. You did not say what length connecting rods but I am guessing by the pin placement in the pistons those are 5.7 rod 383 pistons and they do look very clean.
Many of the older 383 engines used the original 400 rods at 5.565 and those were not long life engines. The switch to the 350 5.7 rod fixed the short life issue and really helped free up internal stress in a 383.
Your cylinders look terrible. I used to take fax film impressions of cylinder walls to help engine builders correct honing issues. I can't say I have seen many that look worse than yours.
I can also state based on fact that your cylinder walls were very rough on initial start up.
Look at your second piston rings. I like to take all 8 second rings and stack them on each other.
Study the area that is still black vs the area that is worn to a chome face on the second rings where they touch the cylinder wall.
The second ring is a taper faced ring. As it wears the taper wears off and the chrome looking part of the face gets wider.
Yours look to be about 85% chrome face and 15% black faced. I say chrome, it is not really chrome face it is just the bare metal of the cast second ring which has been touching the cylinder wall.
In a properly honed engine the shiny part at 5,000 miles should be only 10-15% of the ring face due to break in wear. At 50,000 miles you should see this increase to maybe 30-40% of the face.
Again, your rings are worn 85%. Terrible cylinder finish is the only thing that will wear them consistently this fast. The second ring wear will tell the story.
If your engine had Cast rings top and second ring both will tell the story as both would be taper faced. I think I am seeing a moly top ring in your engine, moly rings are harder to read but the second ring is always cast iron and easy to read if you know what to look at.
Now look at the area of the ring that runs on the ring land. Most do not know it but 50% of ring seal is achieved by how well it sits on the ring land and what speed it rotates at.
Cross hatch controls ring rotation. Rings have to rotate as the piston goes up and down. Proper rotation helps drag an oil film accross the ring face which helps seal the rings.
IF your cross hatch angle is too steep the rings will spin fast and you will have terrible ring seal and it will leave a very shiny face on the ring where it runs in the ring land. Sometimes it will leave a sharp edge you can cut your finger on the inside of the piston ring.
If your cross hatch is not steep enough the rings will not rotate and this too can destroy ring seal but you will see on the ring land that they have not been rotating.
The low milege ring lands of your rings should still be black with the original black or dark grey ring color. If they are worn and shiny chrome looking the cross hatch angle was wrong in your bore.
I suspect all 8 of your second rings will look identical. Study them and you will know the story of your cylinder wall finish.
Your bearing look fine. The outer bearing surface that touches your crankshaft is only .000030, yes 30 millionths of an inch thick it is an overplate designed to keep the bearings looking good while in storage and to help a little with a soft surface for break in.
This outer layer is babbitt material or tin coating. You can scratch this with a finger nail. Copper base material does not show in your pics so the bearings are perfect still.
It is possible that those are aluminum bearings, FM did sell both but either way they look perfect to me.
I would find a good quality machine shop that understands cylinder finish and they can apply a new cross hatch finish while only taking .0005 5/10,000 out of the bore with a torque plate hone.
This would give you a near perfect cylinder bore for your new rings and you could re use the old pistons. They can also tell you if your cylinders were properly bored to begin with for size.
Another option that has been done many times is to install a new set of rings with no other action. Odds are your oil issue will be 80% better. The old rings were used up honing the cylinder for you.
The first set of rings probably wore in a pretty good cylinder finish. Even GM says if new rings are needed in an otherwise good engine to install them with no honing because moly rings like a smooth cylinder.
The new set wil most likely like the new cylinder and run just fine.
If it was me since you already have it out and want it perfect, I would crate it off to the machine shop for a professional torque plate hone. A good machine shop can offer a better than OEM finish, a bad shop can make it look like your current bore.
I knew Mike Lynch well, Mike was one of the worlds top piston ring experts and trainers, Mike not only helped all the large engine builders in the US he had to help out little guys like GM, Ford, Chrysler, Mercedes.
Mike always said to save your Dingle Ball Brush for mixing paint. He said they destroy the cylinder wall for piston rings.
Modern Moly rings need a smooth finish to seal well, they break in instantly and will use nearly zero oil on a proper cylinder wall finish. If a machine shop says it is normal to use 1 quart per 1,000 miles they are a lousy machine shop.
Plateau honing can help with break in and for racers it gives them full power instantly due to less drag on start up. I do not feel it is necessary for any street engine because after 1,000 miles your rings will have done a plateau hone for you.
When you are ready to gap your new piston rings for install the current technology is to run the top ring as tight as you can without allowing it to butt. For your 4" bore this is normally .016 top ring gap. If you run a supercharger or Nitros you will need to add for that extra heat.
The idea is to have the gap nearly at zero when you are wide open throttle to reduce blow by. If you go to tight they will butt and very bad things happen as the ring will tear up your cylinder wall. .016 top ring is known to be safe in a naturally aspirated Small block.
IF YOU RUN Keith Black Hypereutectic pistons you need to add a lot more top ring clearance because Keith Black runs the top ring higher on the piston than other brands and exposes it to more heat.
Second ring: Today you are advised to open it up to .024, this wider second ring gap helps manage blow by that gets past the top ring and this wider gap has proven to add horesepower at wide open throttle and it helps with oil control. The horsepower gain has been published to be no more than 3-5 HP on a 400 HP engine but this is free horsepower and free horsepower is hard to come by. The second ring can be run as tight as .008 without butting because it is further away from the heat but this does not help power or oil control.
Zero oil loss in 3,500 miles is a good number if done correctly today. The OEM's want 20,000 per quart of oil consumption to meet EPA requirements.
One of Mike Lynch's other sayings we always remember. "Compression at wide open throttle wins races, Leak Down tests never win races"
He always said that because some racers wanted zero gap rings, Sealed Power sayed with traditional gapped rings and had a good history of winning races.
We used to help race teams seal up engines, if we looked in the exhaust port of their head it would either be dry and chalky or a little wet and black.
Wet and black is oil consumption. Dry and chalky means it is sealed up well. This simple check helped sell a lot of piston rings and clyinder wall information got them sealed correctly.
Any oil in the cylinder reduced the octane level and cost you power so racers wanted a great oil seal.
No one argued with the head check, it told the story straight up.
All this assumes your heads are sealed up well and not the cause of the oil consumption.
Wow, I wrote too much but you asked a question I thought I could help with.
The crazy hone pattern came from a piece of grit in the rough stones. They probably honed it a little too big with the roughbefore they switched to the finer stones for finishing. That's why no one saw it when it was originally done. It won't hurt anything.
With 30% I would check cylinder taper top to bottom closely. A lot of guys that do hand (dingle ball) honing tend to go a little heavy at the top of the cylinder.
With 30% I would check cylinder taper top to bottom closely. A lot of guys that do hand (dingle ball) honing tend to go a little heavy at the top of the cylinder.
Thanks. I plan on measuring each cylinder very carefully. It was consistent---I had 30% leakdown in every cylinder. When I got the car, it had a newer intake on it without the oil filler, and had the stock non-vented valve covers. The breather in the back of the block was left open to atmosphere. So, no way to put oil in it and no real crankcase venting. Not good! The deck height on the pistons is about .006", which is almost ideal, and the parts look to have very low miles on them. I'm hoping it's simply stuck or defective rings. Appreciate the advice from all of you guys.
Was it pushing oil before tear down? Are they aftermarket rods or original? The original factory rods are the weak point in small blocks.
If it was not using oil I would replace the rods if factory, balance it,new rings and bearings and re-assemble it. I would also port match the intake and exhaust the best you can with your dual quads.
"the builder shaved the rods. But not all of the rods. Just the ones that required it." Good grief! Or, "Are you f****** kidding me?" Can't imagine how upsetting it would be to find that in a motor. If the hone marks weren't causing problems already, they won't after a clean up. Just a glazebreak hone should be enough if all the cylinders are round and true.
Thanks again, guys, and as always, more input welcome. Yes, the reason for the teardown was oil consumption. Blowing out of the breather. I will weigh the rods and pistons to determine if they are consistent. And go from there. I'll do what it takes to make things right. All of that said, this engine pulled like a freight train all the way past 6500 RPM and was as smooth as glass with no vibrations or weird noises. I don't know what cam is in it yet, but whatever it is, it sure works with this combo. The main reason I want to try to 'save' the build is because it just runs/ran so darn well. Can't deal with an oil pumper on my watch, though!
I think your guess of stuck rings is probably right on target. Or maybe even broken rings. All eight cylinders since your leak down is the same. I would have guessed the gouges in the hone job might be a problem but compression and leak down the same in all cylinders............................... ....
The cylinders look like they are torque plate honed. If they are not it would show up polished at each head bolt. If it was plate honed and you measure it without plates then you will see about .0015" out of round. Especially at the head bolts. As far as a dingle ball hone you could put one in the cylinder turn the drill on and an hr later I doubt you would see any change in cylinder shape. I have never seen a dingle ball take any measurable amount out. Myself I'm a real stickler for internal engine parts and only use very good brands. For rings that would be Sealed Power moly rings.
Removed # 1 piston last night....didn't have time to tear the whole thing down. Very interesting. Bearings are Federal Mogul .010" under, and it looks like some slight wear but also, like the coating was starting to fail. This engine sat for over 20 years with filthy black oil in it, so, acidic corrosion, perhaps? The piston looked like it was installed yesterday, with no carbon fouling. I did NOT clean anything in the pictures....the parts are as-removed. The rings were not stuck. Moly top and iron scraper ring. BUT, the gaps were off.....Top ring was .019, and the scraper ring was at .039". More than 3 times the spec, and this ring is all about oil control. The crank looked nice and smooth, with a good radius. I'll find out when I get the other pistons out, but my bet is that all the rings are going to have excessive gaps. This would certainly account for a great running engine that had a lot of blowby. By the looks of things, I don't think this build has 5,000 miles on the clock. I'll find out after I measure the bores, but I'm thinking of a hone and ring and bearing job on this one if the specs are in line. I cannot feel the crazy hash marks in the one hole with my fingernail. Cam and lifters also look like new parts, as well as the pushrods.
I'll admit to having less engine tear down experience than I wish - but those cylinder walls - random honing marks here and there aside - sure look shiny and slick. Not used to seeing a shine/reflection like that in pictures of recently or somewhat used cylinder walls.
Last edited by DansYellow66; 05-02-2019 at 01:17 PM.
Wow, glad you are fixing it. You did not say what length connecting rods but I am guessing by the pin placement in the pistons those are 5.7 rod 383 pistons and they do look very clean.
Many of the older 383 engines used the original 400 rods at 5.565 and those were not long life engines. The switch to the 350 5.7 rod fixed the short life issue and really helped free up internal stress in a 383.
Your cylinders look terrible. I used to take fax film impressions of cylinder walls to help engine builders correct honing issues. I can't say I have seen many that look worse than yours.
I can also state based on fact that your cylinder walls were very rough on initial start up.
Look at your second piston rings. I like to take all 8 second rings and stack them on each other.
Study the area that is still black vs the area that is worn to a chome face on the second rings where they touch the cylinder wall.
The second ring is a taper faced ring. As it wears the taper wears off and the chrome looking part of the face gets wider.
Yours look to be about 85% chrome face and 15% black faced. I say chrome, it is not really chrome face it is just the bare metal of the cast second ring which has been touching the cylinder wall.
In a properly honed engine the shiny part at 5,000 miles should be only 10-15% of the ring face due to break in wear. At 50,000 miles you should see this increase to maybe 30-40% of the face.
Again, your rings are worn 85%. Terrible cylinder finish is the only thing that will wear them consistently this fast. The second ring wear will tell the story.
If your engine had Cast rings top and second ring both will tell the story as both would be taper faced. I think I am seeing a moly top ring in your engine, moly rings are harder to read but the second ring is always cast iron and easy to read if you know what to look at.
Now look at the area of the ring that runs on the ring land. Most do not know it but 50% of ring seal is achieved by how well it sits on the ring land and what speed it rotates at.
Cross hatch controls ring rotation. Rings have to rotate as the piston goes up and down. Proper rotation helps drag an oil film accross the ring face which helps seal the rings.
IF your cross hatch angle is too steep the rings will spin fast and you will have terrible ring seal and it will leave a very shiny face on the ring where it runs in the ring land. Sometimes it will leave a sharp edge you can cut your finger on the inside of the piston ring.
If your cross hatch is not steep enough the rings will not rotate and this too can destroy ring seal but you will see on the ring land that they have not been rotating.
The low milege ring lands of your rings should still be black with the original black or dark grey ring color. If they are worn and shiny chrome looking the cross hatch angle was wrong in your bore.
I suspect all 8 of your second rings will look identical. Study them and you will know the story of your cylinder wall finish.
Your bearing look fine. The outer bearing surface that touches your crankshaft is only .000030, yes 30 millionths of an inch thick it is an overplate designed to keep the bearings looking good while in storage and to help a little with a soft surface for break in.
This outer layer is babbitt material or tin coating. You can scratch this with a finger nail. Copper base material does not show in your pics so the bearings are perfect still.
It is possible that those are aluminum bearings, FM did sell both but either way they look perfect to me.
I would find a good quality machine shop that understands cylinder finish and they can apply a new cross hatch finish while only taking .0005 5/10,000 out of the bore with a torque plate hone.
This would give you a near perfect cylinder bore for your new rings and you could re use the old pistons. They can also tell you if your cylinders were properly bored to begin with for size.
Another option that has been done many times is to install a new set of rings with no other action. Odds are your oil issue will be 80% better. The old rings were used up honing the cylinder for you.
The first set of rings probably wore in a pretty good cylinder finish. Even GM says if new rings are needed in an otherwise good engine to install them with no honing because moly rings like a smooth cylinder.
The new set wil most likely like the new cylinder and run just fine.
If it was me since you already have it out and want it perfect, I would crate it off to the machine shop for a professional torque plate hone. A good machine shop can offer a better than OEM finish, a bad shop can make it look like your current bore.
I knew Mike Lynch well, Mike was one of the worlds top piston ring experts and trainers, Mike not only helped all the large engine builders in the US he had to help out little guys like GM, Ford, Chrysler, Mercedes.
Mike always said to save your Dingle Ball Brush for mixing paint. He said they destroy the cylinder wall for piston rings.
Modern Moly rings need a smooth finish to seal well, they break in instantly and will use nearly zero oil on a proper cylinder wall finish. If a machine shop says it is normal to use 1 quart per 1,000 miles they are a lousy machine shop.
Plateau honing can help with break in and for racers it gives them full power instantly due to less drag on start up. I do not feel it is necessary for any street engine because after 1,000 miles your rings will have done a plateau hone for you.
When you are ready to gap your new piston rings for install the current technology is to run the top ring as tight as you can without allowing it to butt. For your 4" bore this is normally .016 top ring gap. If you run a supercharger or Nitros you will need to add for that extra heat.
The idea is to have the gap nearly at zero when you are wide open throttle to reduce blow by. If you go to tight they will butt and very bad things happen as the ring will tear up your cylinder wall. .016 top ring is known to be safe in a naturally aspirated Small block.
IF YOU RUN Keith Black Hypereutectic pistons you need to add a lot more top ring clearance because Keith Black runs the top ring higher on the piston than other brands and exposes it to more heat.
Second ring: Today you are advised to open it up to .024, this wider second ring gap helps manage blow by that gets past the top ring and this wider gap has proven to add horesepower at wide open throttle and it helps with oil control. The horsepower gain has been published to be no more than 3-5 HP on a 400 HP engine but this is free horsepower and free horsepower is hard to come by. The second ring can be run as tight as .008 without butting because it is further away from the heat but this does not help power or oil control.
Zero oil loss in 3,500 miles is a good number if done correctly today. The OEM's want 20,000 per quart of oil consumption to meet EPA requirements.
One of Mike Lynch's other sayings we always remember. "Compression at wide open throttle wins races, Leak Down tests never win races"
He always said that because some racers wanted zero gap rings, Sealed Power sayed with traditional gapped rings and had a good history of winning races.
We used to help race teams seal up engines, if we looked in the exhaust port of their head it would either be dry and chalky or a little wet and black.
Wet and black is oil consumption. Dry and chalky means it is sealed up well. This simple check helped sell a lot of piston rings and clyinder wall information got them sealed correctly.
Any oil in the cylinder reduced the octane level and cost you power so racers wanted a great oil seal.
No one argued with the head check, it told the story straight up.
All this assumes your heads are sealed up well and not the cause of the oil consumption.
Wow, I wrote too much but you asked a question I thought I could help with.
Last edited by Westlotorn; 05-02-2019 at 08:39 PM.
Removed # 1 piston last night....didn't have time to tear the whole thing down. Very interesting. Bearings are Federal Mogul .010" under, and it looks like some slight wear but also, like the coating was starting to fail. This engine sat for over 20 years with filthy black oil in it, so, acidic corrosion, perhaps? The piston looked like it was installed yesterday, with no carbon fouling. I did NOT clean anything in the pictures....the parts are as-removed. The rings were not stuck. Moly top and iron scraper ring. BUT, the gaps were off.....Top ring was .019, and the scraper ring was at .039". More than 3 times the spec, and this ring is all about oil control. The crank looked nice and smooth, with a good radius. I'll find out when I get the other pistons out, but my bet is that all the rings are going to have excessive gaps. This would certainly account for a great running engine that had a lot of blowby. By the looks of things, I don't think this build has 5,000 miles on the clock. I'll find out after I measure the bores, but I'm thinking of a hone and ring and bearing job on this one if the specs are in line. I cannot feel the crazy hash marks in the one hole with my fingernail. Cam and lifters also look like new parts, as well as the pushrods.
If you find no more damage and the cylinder taper is not excessive, I would do exactly as you plan: properly gap new rings, new bearings and valve stem seals, perform some hand honing and polishing, and assemble the engine.
You could weigh and compare the rod/piston assemblies to ease your mind, but if it ran smooth before...
Considering the rod machine work found, rather than typical the block clearance machining, if it does not perform (short of an oil consumption issue) plan-B would be new rods and the needed machine and balance work while reusing the rings and bearings (and new oversize pistons with machine work if it uses oil).
The point being there is no reason to not try the engine now, when the only lost expense is the rings and gaskets... and your labor.
OTOH, from first reading the thread title it sounded like a personal medical problem....
I wish. A simple roll of TP and a tube of Prep H and I'd be in business. Westlotorn, thank you. What a comprehensive essay you wrote. I'm a mechanic, but not a machinist. I like the idea of taking the block to a good machine shop and having it honed properly. Then, I can fit the new rings and re-assemble the engine. As much as a PITA it is to do the heavy lifting, I don't want to band-aid it with a dingle ball hone or just slip in new rings and run it. I suspect the .039" gap on the second ring helped with the excessive blowby. Plus, the machine shop can verify the bores are straight and round. I would love to be able to re-use my pistons, as they appear to be in perfect shape and well made. Hopefully it won't need a re-bore and new pistons. While I'm at it, I'm refacing the flywheel, installing a new clutch, and overhauling the transmission. Once it's in, hopefully, it'll stay in.
The angle of the cross hatch is controlled by the speed of the hone, its rotating speed and the exact speed it goes up and down in the engine, the amount of pressure applied to the cylinder is also important along with the stone used. We used to say 45 degree cross hatch was perfect but some modern engines use more and some use less.
This assumes you will use modern piston rings with a Moly Top Ring.
Standard top rings even with a Moly face are cast iron. A cast iron top ring can be damaged pretty easy if you have detonation.
A 383 can detonate with 195 PSI compression so for protection you might wish to upgrade to a Ductile Iron top ring with the same Moly face.
Most modern top rings are ductile iron and I think the later model corvette stock engines used the ductile iron top ring in the same 4" bore in the 90's.
They are available and not much money to add some insurance to your build. It sucks to fracture a top ring while you work out the tune in an engine.
I know very little about most parts in our Corvettes but inside the engine, except for cams and carbs I did have some good training and it was a fun excersize to go back and share.
Engines before 1985 or so Cast iron top rings with a cast iron bevel face were the standard ring. Cast iron rings responded well to a quick hone on overhaul.
These went away because even well cared for engines with bevel faced cast rings started using oil after 40,000 miles and the use would continue to increase with time and miles.
The science has changed and modern rings need a smooth finish with a good cross hatch but offered near zero oil consumption even after 200,000 miles but these need a professional hone, not a drill with a hone attached.
Common shop hones are the Sunnen, CK10, CV616, CK21, you may also find a Rotler or Peterson Hone but look for the newer ones that are computer controlled so each bore gets the same finish.
All will still need a good operator for sure but they have to have good equipment to give you good results.
There is no chance I would ever build a bevel faced cast iron top ring engine today but many cast iron top rings are still sold because they are less expensive.
Mark
Last edited by Westlotorn; 05-02-2019 at 05:34 PM.
Mark, your eye did not deceive you on the ring ID in my engine. The top rings are moly coated, the second scraper rings are cast iron. The engine pinged initially when I first got it running, but I fixed the fuel and ignition curve and got it to scream with no detonation on pump gas with about 32-34 degrees all -in. The quench appears to be pretty good, as the slugs are about .006" in the hole max. I will be going for a machine shop hone and will go with premium rings and bearings on this one. Your analysis on the demise of this engine was spot on, I think. The bad cylinder hone and the poorly gapped piston rings doomed it from the beginning. That, and the previous owner was doing brodies with the car in the dirt fields of his farm with no air cleaner in between drag races. Thanks for the solid advice.
Jeff
Damn, this is good stuff, and a perfect example of why I lurk here on the C1/C2 forum. Thanks so much for sharing your knowledge, Mark. It's greatly appreciated.
05-01-2019, 01:37 PM
Dingle-Ball Blues or What's Inside the 383
