Can anyone advise the correct orientation of the piston/rod assembly in a Flathead with a Scat crank? The normal FH rods have an oil spit hole that throw oil to the base of the lifters/camshaft how ever the Scat rods do not have this hole so this is not the issue. Ive been told that the "ROSS" stamping under the piston head faces toward the front of the block and toward the valley/centre of the block when installed on BOTH sides of the engine. My mach shop assembled the pistons/rods with the 1-2-3-4 pistons /rods facing away from the block (ie not toward the valley) asnd the 5-6-7-8 pistons/rods facing toward the valley. Also, when the rod bearings are installed on the rod/cap, it appears to be very slightly offset to my eye and there also appears to be a slightly larger chamfer on that side too. I guess this may be to clear the small fillet radius on the crank itself - can anyone who has assembled and used these specific parts confirm ? I will call them tomorrow but how do you guys assemble these parts with a Scat crank? I wish Flatdog was still with us - he was always such a help to so many of us. Rat
Hey Rat: I believe those pistons are symmetrical - though I'd check with Ross. If they were not symmetrical, I'm sure there would be a notch or mark on the tops. If they are marked with bore/stroke, then I've always seen those marks (on a flathead) setup such that you can read them from looking (from the side) at the cylinder bank - not upside down. If the rods or bearings have more relief/radius on one side versus the other, make sure that side is where the crankshaft fillet is at. I've ran mostly early 21A rods, completely different deal. Though I'm glad you're doing the SCAT ones, then you can school me Are you running the metric rings - with a Moly top . . . or the good ole' traditional (notice I said that) Grant rings? I'd use about .004 to .0045 per inch of cylinder for the top gap and probably .0045 to .005 per inch of cylinder for the second ring. Are you using "file to fit" - or pre-gapped rings?
My ross pistons have a notch in the top and that faces the front of the motor. The champher of the rod bearing goes to the fillet--When installed properly you should be able to move the rods front to rear-If no movement is there something is wrong and you have no side clearance. Rod numbers on my motors have always been on the outside -facing the pan rails. If this is not correct you will have problems. I have yet to see a rod stamped with the number on the wrong side but I guess it could happen.
Thanx for the heads up guys. I figured they were symmetrical. Bu to my untrained eye, there DOES appear to be a slighly larger chamfer on ONE side of the rod/cap. Im gonna install em with that chamfer facing the counterweight/fillet radius and check the rod side clearances when done. Ray, the Scat rods have individual part numbers on the rod/cap - i'll check it out but Im betting that with those numbers facing the pain rail, the larger chamfer will also fit the fillet radius /counterweight side of the rod journal. Dale, the rings are file fitted Grant plasma Moly - was gonna use the metric ones for slightly less friction but decided to just go with these and see how we go. Rat
Hey AFL they are 3 5/16" + .030" - havent got the part # handy atm. As as adjunct, do Flathead Scat rods have an offset rod bearing to allow for the fillet radius on the Scat crank? Rat
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