My Dad, Russ Hill, Sr. Always Respected Mercury Motors and Their Parts
Quote:
Originally Posted by
Trident
Harry had an answer. Maybe right, maybe not, but the beauty of Mod is there can be more than one right answer. On this point, I disagree with him.
But also realize that's a theoretical rule of thumb, the 2 1/2 times bore thing... Note, I also said these heavy section deflector pistons may really need more gap because of heat build up. I didn't have a way to get a tighter gap without using an oversize ring, so I don't really know what is the 'perfect' gap.
In winning motors, no failures is perfect in my book. If it ain't broke, don't fix it.
I'm fine with stock Mercury rings. I still say any extra leakdown is insignificant, at temperature, at speed. Those clearances are far different than what we measure, cold, on the bench.
Jerry
I don't wish to High Jack this thread, but I have a few questions and thoughts. Harry Brinkman and I may have never met fact to face, but he sold 55-H "dead" rings that my dad liked. Over the years, my dad probably machined 200 pistons from castings. It seemed he was always careful to not make the ring grove too deep (Whispered a "Back Gap" in the old days). He also had some a theory for every inch of bore, so many thousandths of ring gap.
I do know my dad was a fanatic about cylinder bore being exactly to MERCURY specs, and once the bore was over like .002, he'd change my blocks.
Once the rule in APBA Stock was changed to any ring, my dad made aluminum rings for the bottom two rings. These rings were the depth of the ring grove and they just butted to the piston pin.
Trident, did you ever run aluminum rings on the bottom two? If you did what was your results?
So, the 44's now have "L" rings???? Shows how long it has been since I took a motor apart. Notice I said, "Take apart" as my dad always put them together.
How much break in time????