4.365 Oil Ring in 4.370 Bore

[Ishiftem]

All I can find is standard tension oil rings for my 4.370 bore. They are 3/16. I can however find lots of choices for a 4.365 bore. What would happen if I ran a 23 lb ring for a 4.365 bore in a 4.370 bore? Or a 18 lb? The second ring will be a napier for a 4.365 bore. No vacuum pump. Just a pan evac to the headers. Thanks!

[PackardV8]

Math says the end gap would be .0157" greater. Also, a low-tension ring in a larger bore becomes that much lower tension.

Let's wait to see what those who've actually done it have to say.

[LSP]

All I can find is standard tension oil rings for my 4.370 bore. They are 3/16. I can however find lots of choices for a 4.365 bore. What would happen if I ran a 23 lb ring for a 4.365 bore in a 4.370 bore? Or a 18 lb? The second ring will be a napier for a 4.365 bore. No vacuum pump. Just a pan evac to the headers. Thanks!

About a 3 lb. change in tension

[MadBill]

A 'file fit' 4.365" ring would typically be +~0.005"...

[Ishiftem]

I've looked through Total Seal, Mahle, and Hastings. The 4.370 bore size is a black hole. I know a file fit 4.365 would technically be +.005 which would be a ring for a 4.370 bore size. They just don't exist except for a standard tension. That's why I was asking about a 4.365 oil ring in a 4.370 bore.

[BillK]

Before you go crazy with this I would pick up the phone and called Total Seal. I think they will make you whatever you want if they dont already have it. Just because its not in the catalog does not mean its not available.

[ProPower engines]

I've looked through Total Seal, Mahle, and Hastings. The 4.370 bore size is a black hole. I know a file fit 4.365 would technically be +.005 which would be a ring for a 4.370 bore size. They just don't exist except for a standard tension. That's why I was asking about a 4.365 oil ring in a 4.370 bore.

If you asked for a +.010 set for a 4.360 bore ( Ford 429/460 ) they can do that guessing you are at .030 over on your current bore. That would be +.010 on std ring set for a 429/460 ford in what ever ring dimensions you need should get the job done.
I did the same thing with a BBC build a couple years back. Asked for a drop in 4.375 ring set no problem.
That would get you your ring set there as well

Just went through the same thing with a 4.105 bore build. Total seal came through then as well

[engineguyBill]

The oil ring assembly is not oversize in file-fit ring sets, only the top and second rings are manufactured .005" oversize. If you can find a ring set that contains a 4.370" ring package, that is what I would recommend that you use. Standard tension oil ring package is the best choice for 95% of the engines on the road.

[Geoff2]

You could use Buick 455 + 060 rings [ 4.312 std ]
or Chrys 400 + 030 [ 4.34 std ]

[Ishiftem]

Called Total Seal. I think it was Bob I talked to. Gave me part # msl9190 130. That has a 12-18 lb oil ring with a Napier second. When I looked it up it’s for a 4.380 bore. No way I’m shoving those into a 4.370 bore. I’m trying to make hp not kill it. Maybe I’ll email Kieth. I think I still have his email.

[Nut124]

Why not file it to fit?

[MadBill]

When you squeeze a ring down beyond its design diameter range, it no longer provides sufficiently uniform contact pressure.

[Nut124]

When you squeeze a ring down beyond its design diameter range, it no longer provides sufficiently uniform contact pressure.

I thought 0.010 over is OK. Not?

[rebelyell]

FWIW
certainly don't suggest following:
a late pal o' mine owned & built & tuned motors for a supertruck CT asphalt piece. Very much like a late model.
Anyway, typical 2 bbl 355, iron bowtie heads, 6" rods, flattops, 5-7 swap, lift rule, flat solids and fuel restricted to track gas.
Pal tried running without any oil rings but with a pan full of Klotz kart oil heavily spiked with methanol.
Man it was fast ... until it loudly broke; terminal