Ring gap

[pistonbroke]

OK , I have a simple question I'm sure for some but to me it's very important . So asking the guys that do and have done it means a lot to me. I'm ready to assemble my piston assembly's for my 53 merc 255. I have Hastings rings and nowhere in or on the package does it have end gap specs that I can find. I was under the impression the ring manufacturer would have their own gap specs, am I wrong? Thanks guys, Tim

 

[Bored&Stroked]

They should - and it should be documented with the rings. If it was mine, I'd call Hastings and ask them (or whomever supplied your pistons/rings).

Here are their general recommendations - which would work fine in your application:

Minimum gap tolerances must be observed in order to prevent the ring ends from butting together as the ring expands when the engine approaches operating temperature. Hastings recommends a MINIMUM of .0035 gap per inch of cylinder diameter. Example: 4″ (bore) x .0035 = .0 14 minimum gap.

So, with a 3.187 bore engine, the minimum ring gap would be .011 to .012. The top-ring usually gets a bit hotter than the 2nd one, so you could use a gap of .013 on the top and .012 on the middle and you'll be fine.

 

[aussie merc]

dont want to hijack this but dose anyone make gapless[overlap] rings in suitable sizes for these engines

 

[5851a]

You could try to contact Total Seal as that name seemed to be big way back when.

 

[Ronnie]

https://www.hastingspistonrings.com/tech_tip/checking-compression-ring-gaps/


Ronnie

 

[Ronnieroadster]

dont want to hijack this but dose anyone make gapless[overlap] rings in suitable sizes for these engines

Yes Total Seal makes them in custom sizes but they are pricey.
Ronnieroadster

 

[GB SISSON]

I have a couple of blocks with very nice bores, no ridge and was wondering what the maximum end gap might be and I'm talking an 'overhaul'. not needing factory new specs. Hasting rings and .017 end gap.

 

[bobH]

I'm a little 'loose' with my thinking, and in response to post 7, me thinks 'big' does not present any substantial problem. 'Course, I'm thinking OLD Fords, patch-um-up anyway necessary. And, NOT high-quality 'race' engines which many folks here tend to embrace.
For example, I patched up the engine in my 47 after it burnt a couple of pistons. This was (is) a worn-out engine, like .020 wear at the top of the cylinders. I replaced a couple pistons (used), and was given some .040 rings. No problem, I just opened the ring gap for a standard bore, and was not too careful about it. It sticks in my mind that .020 or more was 'good enough' in my mind. My point being, that I was very 'sloppy'. And the engine was worn out anyway, so it really needed a much more serious rebuild. The result was (and is) that it has never used any oil, and it has never overheated. Measured compression has held at around 110 +/-. Of course, this is on a low-mileage, hobby car. Am I recommending this? Heck no. But, it's been good enough for my purpose. (So, Hasting rings, and .017, would not be any problem for me. And, on a good bore, to boot.)