Seating rings vs cam break-in? - Chevelle Tech
Engine General Engine Discussion.

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  • 3 Post By bracketchev1221
  • 1 Post By Busted Knuckles
  • 2 Post By jeff swisher
  • 2 Post By Richard/SIA
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post #1 of 10 (permalink) Old Feb 27th, 20, 11:18 PM Thread Starter
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Richard
 
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Seating rings vs cam break-in?

This is going to be an issue several times this year.
Cam break-in, hold at 2K RPM for X minutes.
Ring break-in, vary speed and load.

How is this working out in the real world?

I've just had to tear down my 350 due to VERY poor ring seal-cylinder leakage in the "Good-wrench" replacement engine.

Hone, new rings and bearings, Performer cam and intake.

Engine will be run and adjusted on the test stand before going back into the truck, which is a PITA to work on so far as reaching anything.

Once back in the truck I can do the normal varied load to seat the rings if the cam break-in is not going to glaze them?

Then I have my hot-rod 327, Buick 225, and Spitfire 1500 to do next.

At these gas prices I want it 100+ octane, leaded, and my windshield washed!
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post #2 of 10 (permalink) Old Feb 28th, 20, 12:27 AM
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Re: Seating rings vs cam break-in?

My method is break in the cam first. Then I go for a test drive. While on the test drive I do several full throttle bursts to seat the rings. Its my method and works for me. Good luck.
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post #3 of 10 (permalink) Old Feb 28th, 20, 7:15 AM
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Re: Seating rings vs cam break-in?

If the engine is machined right, ring seating happens almost as soon as it starts.
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post #4 of 10 (permalink) Old Feb 28th, 20, 7:23 AM
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Re: Seating rings vs cam break-in?

Vary the revs when you're breaking in the cam as well, don't set it at an RPM and hold it.

And I've been told by some of the best in the business - builders that I respect - that if the cyilnders are finished right, the rings break in within seconds.
You're causing the SOFT cylinder wall to "break-in" to wear the hone marks to the point where they pretty much stop wearing down and the cylinder seals. Rings don't wear down, cylinder walls do.
Just don't flood the engine when starting it, washing the oil off of the cylinder walls with excess fuel - particularly at this critical time - can be disastrous.
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post #5 of 10 (permalink) Old Feb 28th, 20, 2:27 PM
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Re: Seating rings vs cam break-in?

Rings can wear down but usually the cylinder wall gets worn also.
620 grit plateau hone and Moly faced rings and it will have the rings seated before the starter quits cranking.

The old Datsun Z engine inline 6 ones 240-280-260 would wear the pistons out after 400,000 miles and the cylinder walls looked good. My uncle built a bunch of them and said he had never seen a worn out cylinder in those.. just pistons.

I had 5 of them.

If you go moly faced rings and coarse 240 grit finish you will chip the moly from the face of the rings.
400 grit is as fine as you want to go on a moly faced ring.

I had a friend that said he was going to race me when his rings seated.. this was back in high school.
a week later he said the oil is still fuel fouled and rings were not seated.

I figured it was his 750 holley 3310.
I pulled it off one day behind the machine shop he worked at and pulled the Q jet and adapter off my car and stuck it on his truck. and drove home with his terrible running 3310.

I did not tell him about it.
3 days go by and I call him and ask how the truck is running.
He said man you would not believe it the rings seated a few days ago and it runs excellent.

Good deal I said when are we racing.
He was always busy and it never happened.
Another week went by and I asked if he messed with the carb any .. he said no I have not even popped the hood.

I told him I know that because you have my Q jet on your intake.
I told him waht I did and he set the phone down and went and looked and got back on the phone and said I never had a good running Q jet.

I said You still don't because it is mine and I got your 3310 running just as good.
I want my Q jet back.
Another week goes by and i tried to meet up a few times but he was always busy.

I think it was Superbowl or Orange bowl day and he was inside his house watching the game with a lot of friends over.
I went over and swapped the carbs back and did not tell him for a few days.

He never noticed.

I wonder how many people had issues with ring sealing up and it was carb issues.

I do not do leak down tests.
I will do a compression test.

Here is why.
I had busted top rings on 4 pistons from very large piston to wall clearances and piston rock along with crappy shaped worn out cylinder walls.
The car got 18 MPG did not use oil revved to 6500rpm.
But 4 holes on that 350" chevy during a cranking pressure test were ZERO.

Pull those plug wires off those cylinders at idle and idle would not change.
Rev it up and it was rough as heck with the plug wires removed.
Plug them in and after 1500rpm or so the engine smoothed out and ran like a dream. I had 268H cam in it and ported and milled 624 heads.

Now I figured at higher rpm ..(above Idle speeds) the air in the cylinder just does not have enough time to get past the piston rings.
Some will get past but not as much as you think will.

So leak down tests for a daily driver is not something I car much about.

That engine got a fresh bore and hone and piston to wall clearance was set at .0015" it would not rev at all now and way down on power. 5000 rpm is all she had ..I bet leak down was better but moot point it was now a turd on wheels.

What makes you think your rings are not seated???
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post #6 of 10 (permalink) Old Feb 28th, 20, 3:40 PM Thread Starter
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Re: Seating rings vs cam break-in?

50%-70% blow-by is unacceptable in any engine.
I could clearly hear the air going into the block, past the rings.
This should explain my poor mileage and low power.
Freshen of the bottom end cost less than the upgrade heads, and half the NV4500 tranmission price.

Not sure why the rings were leaking so badly, no pitting or gouges in the bores.
Thinking the truck sat longer than the seller let on.

In any case I will now have an engine for which I know the exact specs and mileage.
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At these gas prices I want it 100+ octane, leaded, and my windshield washed!
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post #7 of 10 (permalink) Old Feb 28th, 20, 4:21 PM
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Re: Seating rings vs cam break-in?

Quote:
Originally Posted by jeff swisher View Post
That engine got a fresh bore and hone and piston to wall clearance was set at .0015" it would not rev at all now and way down on power. 5000 rpm is all she had
Maybe I missed something else you were saying in your post, but a .0015" piston-to-wall? I'm sure no pro engine builder, but I've never heard of any pistons calling out for less than .002" piston-to-wall, and those are hyperuetectic pistons, not forged. Could the miniscule .0015" p to w have been the reason for the lack of RPM up top?
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post #8 of 10 (permalink) Old Feb 28th, 20, 10:26 PM
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Re: Seating rings vs cam break-in?

Quote:
Originally Posted by BillyGman View Post
Maybe I missed something else you were saying in your post, but a .0015" piston-to-wall? I'm sure no pro engine builder, but I've never heard of any pistons calling out for less than .002" piston-to-wall, and those are hyperuetectic pistons, not forged. Could the miniscule .0015" p to w have been the reason for the lack of RPM up top?



It absolutely was the reason for lack of RPM..after 35,000 miles it would rev to 5500 rpm but was still way down on power.
I think that was an absolute minimum spec, the pistons were cast Zolner. spelling may be off on that.


That is the first time I had a block bored and honed and did not know what to ask for. and the guy did not know how i drove my stuff. Just simple lack of communication and lack of knowledge as iI was younger then..I knew all about making power by porting my heads and porting everything else though. Setting timing curves and building all kinds of carbs.
Just never had an engine that needed any pistons other than what the factory stuck in them. I got a lot of really good engines way back then. Virgins that ran.



here is some chart from KB- silvolite on ring gap and piston to wall.
#2---- Clearance Requirements for Hypereutectic Pistons
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post #9 of 10 (permalink) Old Feb 29th, 20, 12:01 AM
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Re: Seating rings vs cam break-in?

Sunnen CK-10 or similar
deck plates
400 stones
single moly quality rings
proper assembly, which does not include dunking the pistons and rings in oil

rings will be seated on the engine stand or on the starter
good PCV and breather

let it rip
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post #10 of 10 (permalink) Old Mar 1st, 20, 9:06 AM
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Re: Seating rings vs cam break-in?

Quote:
Originally Posted by Richard/SIA View Post
This is going to be an issue several times this year.
Cam break-in, hold at 2K RPM for X minutes.
Ring break-in, vary speed and load.

How is this working out in the real world?

I've just had to tear down my 350 due to VERY poor ring seal-cylinder leakage in the "Good-wrench" replacement engine.

Hone, new rings and bearings, Performer cam and intake.

Engine will be run and adjusted on the test stand before going back into the truck, which is a PITA to work on so far as reaching anything.

Once back in the truck I can do the normal varied load to seat the rings if the cam break-in is not going to glaze them?

Then I have my hot-rod 327, Buick 225, and Spitfire 1500 to do next.
If itS not plate honed rings will really never seat. I have seen circle track engines not plate hone blow oil out the breathers for 3 years do a leak down 35% leak down, Rings will not seat to a distorted cylinders. PERIOD. Leak down test 40 degrees BTDC or ATDC This is a factory 604 circle track engine, This is the Best GM can do.



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