- in association with IPE, my "local" Indian shop - Part 2
I get the distinct feeling I'm being punished for interfering with all that is holy and Indian with this engine, it's as if the great spirit is testing me...
For this installment I tried fitting the new IPE flywheels into the crankcase but, on doing so, I had 3/16" end float to contend with, and I could not for the life of me see why? Not a satisfactory situation to find oneself in. After measurements from the old and new flywheels were checked and found to be so close that it made no sense at all, there just had to be a problem with the crankcase!
It had me mystified and bewildered to start with, as I could not see anything blatantly obvious that could cause this amount of discrepancy, but the only possible explanation was that the driveside bearing race outer (#40871) had moved...
Sure enough it had. The race retaining nut (#28B161) had stripped threads, I guess from a previous repair, and was held in place by the outer race having been peened over like riveting the thing in place, then burnished to an expert finish to the point were it was almost undetectable... I should think it was done at a time when labour was much cheeper than replacing with a new part.
Here we go again, into the initiative box for pulling outer race bearings from crankcase halves.
I had to split the retaining nut with a side action grinder as there was no way it would come undone in the conventional way.
A block of aluminum was turned to a cone shape so that it centered in the race. I then cut a length of 3/8" studing 14" long with a nut each end, and an 8" length of 2-1/2" diameter 12 SWG tube with a 1/4" thick washer welded one end, and thus had just the puller I needed.
The puller was treaded trough the bearing race and case. Then the whole thing was screwed onto a wooden bench with 4" #8 wood screws and washers. This has the function of another pair of hands that don't mind the heat!
I heated the crankcase half up evenly with a gas plumbing torch untill my spit bounced off, so thats at 200F - don't know what that is in centigrade; I can't spit in metric! Once I was confident there was enough heat I wound the nut up on the studding and pulled the race out like pulling cork out of a bottle of... Merlot! I know most of you reading this are more familiar with "screw-top" wine, but I am sure you can imagine.
Having done all that, some things have gone wonderfully easy. After a trip to my rebore man Paul (son of Hedgehog) Watson, another ex grasstrack racer like me, we found that the only attention the cylinder bores needed, which would suffice to give the appropriate piston clearance, was a quick hone.
As I said, Paul is an ex grasstrack racer and was still campaigning mid-1950s JAP 350 and 500 4Bs in the late 1980s when the trick rides were 5 valve Weslakes and OHC Goddens - and sometimes beating them. His dad Tony (Hedgehog) would rather have died riding those JAPs than be beat by a Weslake when he did grasstrack!
So he was quite familiar with the use of methanol as a fuel, the growth of cast iron bores in action, and the use of forged aluminium pistons. I have seen the effect of too tight a clearance on forged pistons, they don't just seize-up, the damned things try to turn inside out!
The information that came with the JE pistons state "set clearance to .0035". SOME applications may require more". When Paul rebores for sidevalves (flatheads) he will normally go for .0040". His quickest JAP 500 4B (cast iron, but OHV) was set up with a clearance of .0070", and sounded like a jackhammer for the first 5 minutes of running until the piston swelled and filled the hole!
Over two pints of "Bishop's Gonad" ale in The Ship pub (opposite his workshop) it was concluded - unlike the recent discusion on the VI mailing list about thermo-growth! - that a safe bet of .0050" was to be used as clearance.
The barrels (cylinders) are in remarkable condition, as you can see. The silver that adorns the cylinders is not paint, but the original nickel plating!
Earlier Installments of the DiXiE Story:
Part 1 - Presentation
More Chouts and Vintage Sprinting:
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