Easy Rhino

I can't help with the expertise above; however, it does not appear that the engine had been previously assembled in a truly clean environment. You have the opportunity to rectify that now. It's always amazing to me when guys spend a ton on quality parts, and a ton of time selecting nicely matched parts, then toss them together in a filthy environment.

My .02, and worth every cent you paid for them.

What's great is that you're taking the time and effort to fix your engine now instead of letting it run down to early failure.

GTOguy

It was put together over 25 years ago.....on a rice farm. Probably by rice farmers. The previous owner did some time courtesy of the State for meth. I think the engine was assembled prior to his 'vacation'. Spun people can lead to spun bearings, IMO!!! It's going to be fixed right this time. Hell, I'm even going to replace all the core plugs!

Easy Rhino

That's quite the tale there!

It's great that the car fell into responsible, caring hands.

(you're not a crack head, I assume)









j/k

Robert61

I'm losing something in translation. In 12 you say the scraper has .039" end gap, in 17 you say second ring. .039 on a scraper wouldn't bother me. My guess is .039 on the second ring is from wear due to the honing process. When you see the face of the ring worn that much it added several thousandths to the end gap. I'll have to take your word for those being moly as I can't tell from the pics. When I see the very top edge worn it would indicate a cast top ring but it doesn't have enough wear to match the second ring. A good hone and new rings and you should be good to go. At least you don't have broken ring lands or galled pistons. If it were mine I would shoot for .015 top and .017-.018 second.

Westlotorn

The Top Ring if you look has a straight line right at the top. This is the top of the channel, there will also be a thin line at the bottom of the ring and the moly is laid into the channel.
These rings are so worn it looks like the moly is worn away and the channel is wearing also. normally the top moly ring has a barrell face touching the cylinder.
In this engine it looks like the moly barrel face is worn flat due to lousy cylinder finish.

The Top ring gap is better the tighter you run for sure right up to the point where they touch and it tears up the bore. The industry says .004 per inch of bore is safe.
I knew racers that would tighten the bore by a 1/2 Thou every time they freshened the engine till they started seeing witness marks where the gaps were just starting to touch.
At this point they would back off a 1/2 Thou and leave it as the correct ideal gap for that particular engine in that type of racing on that exact fuel.
Guys on Alcohol engines could run .012 because alcohol burns a little cooler and the piston ring was not exposed to so much heat.

I am pretty sure at .004 per inch of bore you are totally safe and I am sure there is a safety margin built in so .015 is probably fine.
Sealed Power did some tests and used the SBC as the test mule. The first test was done with top ring gaps at .024, the second test was at .016 and a third test was done at .010 top ring gap.
Between .024 and .016 blowby was reduced by 50%. At .010 blowby was reduced again but horsepower fell off. On tear down the rings were butting at .010 causing drag.
Maybe they should have done more tests at .014 and .012 to see what happend but they only did the first three to get a baseline.

The wider second gap was invented by Sealed Power back in the early 90's. The first application to use the wide second ring gaps was the 7.3L Ford Diesel. The factory was having real problems with this engine burning oil.
Sealed Power Engineering helped Ford fix this issue, they opened up the second ring gap with no other changes and the engine stopped burning oil so Ford made a running change.

The engineers told some racers about this new technology at first and they started trying it and found good results. A few years later it was in print and advised for all engine builds.
They said at the time that combustion blown past the top ring was getting trapped between the top and second ring. This pressure between the rings was lifting the top ring off the ring land at the bottom of each normal stroke.
They called this top ring flutter.
By opening the second ring the pressure would escape into the oil pan and the top ring would seat faster at the bottom of the stroke eliminating top ring flutter.
The high compression diesel application exaggerated this issue helping make this discovery. Today all OEM's and most engine builders will take advantage of this simple trick to make a little better power and help ring seal.
When this came out the gap we recommended was .024 but that was in the early to mid 90's. I checked Sealed Power's current guide tonight printed in and for a street engine they say .020 to .022 updated in 2015. Sorry I was out of date.
If you add Nitros, Supercharger, Turbo the second ring gap should be .024-.026 or oval track racing should use .022-.024. I should try to stay up to date.
Sealed Power manufacturing was sold to Hastings Piston Rings several years ago so most of that engineering information access moved along with it, SP did sign a supply agreement with Hastings and the rings are mostly made on the same equipment today just different owner of the equipment.
It does help seal the engine against oil burning. It does offer a very small Horsepower gain, as mentioned 3-5 on a 400 HP engine. That is small for sure but free.

Robert61

I agree mostly. I built race SBCs for years almost all 4.125+ bores. At first we used .014 top .012 second. As time went on everyone moved to a wider second ring gap, race and street. Racing figured out the increased ring gap on the second ring decreased ring flutter. Personally I don't feel you need .024 end gap on the second ring. Just by looking at your stats it tells me if I have tightened up the top bores to .015 and decreased blow by by 50% then I don't need a huge increase in the second ring to let gas by. Maybe 8 years ago a new trend started showing up where you had to cut the oil ring rails. This absolutely drives me crazy as there is no logical reason in the world for this. I first noticed it in brand X racing pistons. I thought they possibly boxed the rings wrong. Then it moved to more brands. I asked them what's up with this. They said they knew it wasn't necessary but they got too many complaints about the end gap on the rails so this was their fix. If you can run .025 on the second ring .050 wouldn't hurt a thing in the rails, JMO.


Foot note, I still have a few Briggs racing engines the end gap on the top ring in them is .0015". But they are air cooled and the cylinder expands as much as the piston and rings do.

GTOguy

Mine are .019 top, .039 second, Robert. Others may be better or worse, but I expect about the same. Looking at the rings physically, it appears that they were file-gapped too much, at least the second ring. The top ring may have worn out of spec, but the second one was installed with a huge gap. I call the second ring a scraper ring, as it scrapes oil downward. I didn't mean to confuse it with the oil scraper rings at the bottom of the piston with the expander. I'm tied up at the moment, but expect to get it all the way apart in the next few days and off to the machine shop. Will keep all of you folks posted as to my findings! Again, appreciate all the help here. Lots to learn.

Robert61

I was pretty sure what you meant just verifying. We were doing a magazine article and when the engine was installed on the dyno it smoked like a freight train. The builder was a very conscientious guy but had installed the second rings up side down. I don't remember the circumstances as to how he was confused but I can say the owner was not happy. Lol The end gap on the second rings is not super important. As much wear as you have on the face of the rings is would have easily increased the end gap.

Westlotorn

One more thing on ring gaps to remember. If you buy a packaged set of rings with standard gaps the rings are sized to fit at the oversize ordered.

If you have a 4.030 bore and order rings, E251K30, std Moly rings for this 4.030 engine they are supposed to fit correctly, most times if your bore is exactly 4.030.

If you choose to run the engine loose and bored it to 4.031 rather than 4.030 the ring gap will increase by the .001 x Pie or 3.14.
So the standard .016 ring gap built in will now be .019. .016 + the extra .001 bore x 3.14.

Westlotorn

Side Note Robert, you mentioned the Briggs engines. I was in a machine shop and heard a really odd sounding engine winding up. The owner took me back to observe his dyno test.
They had a 5 HP Briggs and Stratton making 40 HP running on the dyno on NITRO. It sounded healthy as hell. It was built for some class of the exhibition drag racers the NHRA had running for kids.
That was a good 20 years ago, they probably make 60 with those engines now. Racers are nuts, always pushing the envelope. But it is fun to see.

Robert61

I have 3 Briggs of various CCs. The biggest is a 3x3 bore and stroke. It's pretty stout, turns just over 10,000. I had a dyno we ran the stockers on. It had a 200 lb. flywheel and I wouldn't want to pull a high hp motor on it. The guy that was running these is now running a single cylinder 460 CC motorcycle engine. I guess my Briggs are finally done in.

427Hotrod

Westlotorn.....EXCELLENT information! Folks....this dude understands what he's talking about....listen to the man!

Thanks!

JIM

Westlotorn

Thanks for the kind words Jim, I just was lucky to work with some good people and some of what they shared sunk in.
Mark

cardo0

Crank looks good - I like the corner/edge radius. Bearings show no real damage so nothing to fail the crank there. If pistons are all good a re-ring and re-bearing may be good enough. The Gen I rods have weight pads top and bottom so not difficult to match weights with those when your ready.
If it were mine and I wanted so save money I would just borrow a 400 grit 3 leg drill hone. Well those are difficult to find but Lisle tools has a hand drill hone that you can buy 500 grit stones for. Lisle also has a $40 glaze breaker but that is only 320 grit and I don't know how much metal that would remove how fast though it seems to be made for your situation.
Hone and wash the block maybe all it needs and would be simplest way to go. Yea deck plate honing is tops but in this situation your not trying to remove any more metal so why go there?

Any kind of boring and your into an engine build with at least new pistons and really a different show/situation.

JohnZ

When I was running my AA/FD back in about '61-'62, I ran it occasionally at Motor City Dragway in New Baltimore, Michigan, and there was a guy back then running a WHIZZER Sportsman on nitro, centrifugal clutch, V-belts and all; never saw him make a successful full pass, but it was a glorious sight to see when it blew up!

Westlotorn

John, I had never heard of a Whizzer before. Looks like a high tech bicycle. On Nitro! Wow. Rider is lucky to be alive.

GTOguy

I measured the rod journals on the crank....all are between 2.092"--2.10".....which is strange since the bearings are marked .010" oversize. I thought the standard rod journal diameter for a 400 crank was 2.10"? Bearings all look excellent with the exception of one, which has a tiny groove from a piece of grit. No marks on the journal, and the groove is too small to be of consequence. It has forged pistons marked .030", but all the bores measured between 4.022" and 4.027". I measured for taper and roundness (without a torque plate, so rough measurements) and got .005" on #5 and # 8 holes, with .002" on all the other cylinders. So at this point, I'm going to take the block, pistons, and crank to a machine shop and have them looked over. Hopefully a hone job with a torque plate, a slight polish on the crank (if needed), and I can fit and gap new rings and get it assembled. All the pistons look 'as new', and all the rings are worn out. Will keep updates coming.

Robert61

What are you measuring with? The numbers can not be correct. A .030 piston wouldn't go in a 4.022 hole. A std rod journal would measure 2.0986-2.0996. It is referred to as a 2.1 but that isn't the actual measurement. A .010 under would usually be 2.0895. Some would refer to the mains as 2.45 but they would measure about 2.4485-2.4495 so a crank ground-.010 on the split would be 2.439-2.4395. Your bores would be 4.030-4.031. I wouldn't run anything larger than 4.0315 with your pistons. If you would prefer I not chime in just drop a quick pm and say so.

GTOguy

Robert, I appreciate all of your comments. Chime away. I am using a standard caliper and a bore gauge standard. Not the right equipment for the job. No real way to get the bore bar square every time without a guide. And hard to measure the bar with a caliper and not a mic. Another reason to have a machinist mic everything when a torque plate is installed. Agree that my measurements defy the parts that are installed in the car!!