1st - 2nd Ring Gap Discrepancy

[mopowers]

I went to gap the rings on a 408 I'm putting together. The rings are from Total Seal (#CR3690-30) and the pistons are from Icon (#745.030). The bores all have a fresh 4.030" torque plate bore/hone job.

The pistons call for a 0.004" ring gap factor for my application, which would be a cunt-hair over 0.016". I set the top rings at 0.018" (one went to 0.019") just to play it safe. Out of the box they were about 0.015" - 0.016".

When I went to set the 2nd rings, all of them were 0.023" out of the box. I guess I'll leave them there and they'll likely be fine since I was planning on gapping them at 0.018 - 0.020" anyway.

Question(s) - Shouldn't the rings come in on the snug size to allow folks to set the gap where exactly they want them? Are there any problems running a .005" larger gap on the 2nd ring than the first? I doubt it, but wanted to double check as in the past, I've run equal gaps on both rings.

 

[crackedback]

No issue with a wider gap on the second ring. If they are too tight it can trap pressure and cause the top ring to flutter (BAD)

Lots of article about this on the net

 

[Kern Dog]

The Hypereutectics in my 1990 360 are different...

The next one is what came with my 440/495 pistons from Icon:

Some will say that a wider gap is MUCH more preferable to a tighter gap.

 

[mopowers]

No issue with a wider gap on the second ring. If they are too tight it can trap pressure and cause the top ring to flutter (BAD)

Lots of article about this on the net

Thanks Rob. I figured as much. It was just weird to me that the gaps on the 2nd ring were that much wider out of the box than the top rings. For a second I figured they put the wrong rings in the box. I'll run them as-is.

 

[crackedback]

It's fine. Wider is better than not enough!

 

[mopowers]

It's fine. Wider is better than not enough!

Totally. Thank you!

 

[Desoto291hemi]

Those rings are correct for what you ordered .
If you wanted to file fit them,,,,you needed .035 over rings .

I’m pretty sure you will be in great shape as you are .
Those gaps you reported will be okay for what you have .

Good looking block by the way .

Tommy

 

[Bewy]

I would open the top ring gap to 0.019"- 0.020". If the engine ends up running really cool, the ends may butt. That will then cause bore glazing. Ask how I know.....

 

[famous bob]

Thanks Rob. I figured as much. It was just weird to me that the gaps on the 2nd ring were that much wider out of the box than the top rings. For a second I figured they put the wrong rings in the box. I'll run them as-is.

must not be oversized rings to start with ..

 

[92b]

Total seal always says " Make us your first call". I would check in with them for your own peace of mind.

 

[mopowers]

must not be oversized rings to start with ..

Must not. It was just weird to me how the top and second rings had different gaps out of the box. I hadn't seen that before.

 

[mopowers]

Yep, we're good to go. According to Total Seal, they specifically make this particular set with larger ring end gaps on the 2nd than the top rings. I'm glad I ran into this since I'll be building a stroked big block soon as well. I'll be sure to specify a 0.035" ring pack (or 0.005" over whatever the final bore size is) for that build.

 

[AJ/FormS]

IDK anything about strokers.

My engine is just an alloy headed 367, with roller tipped 1.6 arms...
On the street
With Hypereutectics, at .065 ring-factor;
I had nothing but overheating, and the engine locked up every time I shut it down. The waiting time to restarts was 10 to 20 minutes. At the first, I was running a 292/292/108 cam, at 11.3 Scr; But it did exactly the same with a 270/276/110 @11.1/Scr.

I tore the engine down, had the holes honed out a little bit, and installed file-to-fits, at .085 factor on the top, and .075 on the seconds. The LD, at 80psi test pressure, was less than 4%, right out of the gate.

Instant relief/No more problems.
This was MY experience ,
yours may vary.

and the bonus came ~4 years later;
With the next bigger cam, 276/286/110,
car went 93 in the Eighth@3457 pounds@900ft elevation, with 3.55 gears, and 325/50-15 T/A DRs

At the first, back in 2004ish, with the pistons now at about .0040 clearance, yes on cold mornings they did rattle a bit. I solved that with a 195 stat, restricting my bypass, and I installed a Ford Thermostatic clutch on my fan, and she now runs 207*F at the stat-house; and all is quiet within less than 2 minutes.
I feel that, the additional skirt clearance may not have been required. My machine shop had refused to put the hypers in at the KB recommended specs, and he had fit them at .0035. which I later increased to .0040.
I'm not sorry at all.