I guess the title asks it all, when installing aluminum pistons the slot faces the camshaft, but why ???
Is it because the non slot slide has the vertical thrust on it, l cant find this detail anywhere.
It cant be for oil as the piston does not travel that far down to allow oil to splash into it.....anyone know why ??
Slot goes away from camshaft.
Hi dave, up and about early or just getting home from work?
Aluminium Alloy pistons has a greater rate of expansion compared to the cylinder block, slotting is a design to over come that.
Hows it all going together, clearences all working out?
Good morning Frank , all going very well, have to stop this 13 and go back to the other 13, Xmas party last week problem, but it'll get there, l have you parts sourced and will be back down soon with a few christmas replacement gifts for you.
It looks great so far.......thank you very very much for the enormous amount of time you spent with me showing how these things all work and are done, if only i'd taken the camera out of the bag !!!!
Up early, thought about mowing the rest of the lawn, but after yesterdays torrential rain storm, thats a non event now.
Do you have your Bigpond back up yet, they've had some big dramas yesterday !!!
A PS Dave, Stev is right,
unless the fitting instructions tell you different fore some designs, the split will go on the left side.
I went to Melbourne yesterday and was lucky enough to miss any storms, we only had light rain at home.
I'm still trying to get my new computer up and running the way I am used to after the last storm our way fried it, today my mission is to re-do all my books for the last 5 months.
Thats what l thought away, but EGGE asks for it to the passenger side, ??? ok in the US where they're from that would be to the cam ??
I dont know, l'll just do as l have done in the past, away.
Expansion slot always away from the cam, no matter what a misprint might say. About 20 years ago, give or take, Sterling Pistons droped the slot in their pistons, that they made for the Model A, in which they looked like Fords. My first shipment with out slots, I called my Rep. and first he said they really don't need the slots, and I kept at him, and he admitted, it was a cost cutting measure only, but he assured me that I could put in the missing slots, and I told him I could, but I would not finish their pistons for them, so we changed brands. Herm.
Not all Herm, some are assembled with the slot on the thrust side, Reo, Packard and V8 Fords since 1944, although the splits will be shorter than normal.
Sorry Kerry, I thought I was on the Model T Forum?
Herm is right, this is a model T Forum and the slot faces away from the cam.
That it is, but we are talking modifications aren't we, Dave has his fitting instructions, there is at least 5 different slotted piston types.
OK, back to the original question , WHY ???
Why as to a split skirt on the thrust side? it wasn't just a factory thing for some model engines, after market pistons came with fitting instructions for that way too.
For a given piston clearance these pistons run quieter, that was the theory.
OK, so what happens if you run a piston designated with a slot away from the cam, facing the cam ??, do it make a difference at all ??
lets try "does" instead of "do"....fast fingers slow brain.....well thats what my wife say's.
First Dave, what type of slot does your pistons have, ie, hole drilled half way up the skirt and slotted to the oil ring?
G'day Frank, l'm fine here, just curious about why and what for, l think l asked this question last time l rebuild Rose's 26, not sure the answer was forthcoming then, but any ways l guess we may never know what happens when you turn them the wrong way ???
My slots "EGGE" slightly slanted slot with the hole in the bottom.
Got the lawns mowed, covered in wet grass now.
I bet at least one set has been turned the "wrong" way and that they worked just fine.
The reason the expansion slot is put away from the thrust side, is the piston with the slot is weaker then the thrust side, and or the side with out the slot. When the rod comes around on the crank, and it is in the downward rotation on the power stroke, the piston top is pushed left, and the bottom right of the skirt, is thrust in to the cylinder, and if the skirt on the right, had a slot, it's pressure could split a piston, especially in cold Temp's. Pistons that I have seen with out expansion slots, and we don't use them. Expansion slots are put in to keep pistions from scoring, and rattling. A cold motor should always warm up a few minutes, even in summer.
Dave, some 40 years ago and a different hobby, skirting pistons on both sides for a drag racing car, 6 cyl GMH motor, Ford pistons, for quick expansion issues, block full of casting sand and no out side moving parts etc, from cold to flat out for a 1/4 mile, we never broke any skirts, but melted a few pistons from time to time on straight ethonol.
Ya, some people never get Hemorrhoids, so whats your point?
Point being, It's not the end or the world if using skirted pistons on the thrust side.
You are right Kerry, ya wouldn't think it would have much to do with ending the world, but a Guys motor?
Well, you can always say, I didn't think it would put that big a hole in your Block!
I would not put a piston in knowingly the wrong way, but if it happened and has to engines, the type of skirting used on the egge would be the least likely to give any trouble.
Herm, what do you think happens to the skirt side of a piston when the energy force is reversed, ie, the crank is now the power driven by the rear wheels, when using as a brake or over running on a down hill grade or a abrupt gear down change?
It is doing the same thing as before. Only the power stroke doesn't have as much stress on the piston. The piston still cocks to the left on the top, and right on the bottom and the force does not reverse it is just not pulling and if you let the R.P.M.'s get to high, it is way harder on the motor then pulling at the same speed, and again, whats your point.
Point again, being is we are not going to end up with an engine that will self destruct and have a big hole in the block as you seem to think, the forces of thrust work on the piston both ways.
"Thrust varies from side to side of cylinder wall in accordance with the angle of the crank pin and the particular strock of the cycle"
(digest of automotive engine re-conditioning)
The design of modern pistons will take the strain either way.
Ya, if they don't have a expanson slot. Modern pistons don't have anything to do with it. The subject is sloted Pistons. I am thrilled you can read an auto magazine, but I think your information, is about 80 years to new. Unless you are going to try to pound in a half set of 454 Chevy's, into a Model T block.
Herm! you are never to old to learn. Cheers.