26-12-2018, 05:03 PM
(26-12-2018, 04:20 PM)Greig Smith Wrote: Hi Chris, when we rebuilt the motor of the green single seater we lightened the flywheel by 2.5 lbs as that is what the 750 bulletins of the '50's recommended, it worked so well that we did the same when built the blue supercharged single seater, HOWEVER, both are race cars so the ring gear came off as did some material from the back of the flywheel and the edges were all rounded to loose weight & we thinned the pressure plate to just the width of the clutch lining
It worked for our purposes as both cars rev easily to 6000 rpm, however for a road car I wouldn't suggest more than 0.5 to 1.5 lbs - the middle road of 1 lbs would make a positive difference in revs, but without sacrificing the rotational inertia needed for smooth ascending of hills etc. This is one of those cases where less is more, so even 0.8 lbs would be good.
Probably the single biggest improvement you can make is to balance the motor - crank, rods, pistons flywheel & pressure plate
That and meticulous assembly where you make 100% sure that the oil jets squirt into the crank pockets by doing the pump paraffin exercise - try get hold of the Mike Forrest double oil conversion bulletin - you can stick to single jets, but bend them as Mike suggests to ensure that 90*+ of the crank rotation is being fed oil = maximum survival for the motor. A little over-bore on the oil pump won't hurt either.
Aye
Greig
No jets on my engine Greig!
Your thoughts on amount of mass to remove are instructive, thanks for that. I will either weigh the assembly or perhaps work it out by adding up how much has been removed (the former might be safer).
It's for a road-going car though and I'm more concerned to understand how much you can get away with from a strength viewpoint when chain drilling a flywheel & clutch. Used to be fairly common practice I believe so must be some experience out there.