Hello Fellas!
The Petronix conversion isn't exactly a "drop in" modification. Its actually a kit for another distributor and slightly modified by adding a stock rotor button via a little milling and superglue. I'll get the kit's part # from My dad as this was his concoction. I was a little critical of it, but its held together without a problem.
I really don't like the limits on advance/retard of the petronix conversions. We only have 16 degrees to play with in timing the engine. I prefer a vacuum disabled distributor with good old fashioned points stiffened by an additional point spring. We have one modified by reworking the mechanical limiters on the centrifugal advance mechanisms that give a full 40 degrees advance without vacuum.
The initial timing is at 10 degrees BTDC at cranking with the petronix and will only advance to a total 26 degrees. This is something that just can't be corrected with the petronix limitations. It is working fine and without one single hitch, I would just like more timing to play with - I suppose its just a little hangup of mine. This petronix system has worked without a problem up to 6000 rpms so I am complaining about nothing I suppose.
Dad is keeping an eye out for the "new improved" petronix "dual dwell" system that is supposed to overcome the advance limitations. I'll keep this board posted on what comes out of that. I suppose We will use such a conversion on the distributor set up for the total mechanical advance of 40 degrees and see how it goes.
Carlo, glad to hear your battle with the Ball&Ball's is coming around. I still think you need to guage the diamter of the air bleed in your air horn and match it up to your idle circuit jetting. This could be part of your problem at the "stomp it" phase of transition between carb circuits. Keep swapping that accelerator setting around until you get comfortable with the amount of "shot" you get. I suppose you need to determine if the hesitation is a temporary richness or leaning out.
DEL - good to see you back reminding us of those often overlooked nuances, it would be perplexing to have a nice chain-type cam ground and hook it up to that gear drive.
In more general discussion, a little exploratory tear down was done on the little 230 to see how things were going before the start of a new season. It needed a beefier clutch as the previous one was the source of alot of smoke during last year. The oiling modifications evidently were the trick to keeping things intact at such rpm. The rod bearings looked and spec'ed out as good as when they were installed, not one blemish whatsoever. Del could probably discuss the merits of shot peening better than I could, these rods weren't shot peened; however, they were resized with alot of detail regarding concentricity and correct crank fitting. I suppose we will run this engine another season to further explore just how much a stock setup can handle in terms of rpm. Its not going to do much more to turn more as I suspect our cam is not going to add anymore power at a higher rpm than we are already running.
My thoughts on reliving the block are this, not the best idea. For street running where compression is a variable leaning on the low end of the scale, perhaps its the best modification. However, if you are going for an all out competition engine, this just creates more cc's of volume in the combustion chamber that cannot be taken up, hence a loss in compression that cannot be gotten back as in an OHV engine. I'm looking at different heads for these little flatties to attempt a modification over the piston.
I would much rather do some relieving in the head above the piston that would accomodate flow, in an area that can be taken up by a dome modification on the piston, than hogging out the block over to the edge of the bore. In another criticism of relieving the block, I just don't like flame path after you cut a trench across the block to the piston's edge at TDC. It just stands to reason that the air/fuel mix is heating as it enters the combustion chamber and would want to rise by simple thermodynamics, there should be a way to relieve the head accomodating the same added flow capacity of a block relief, and recapture some of those additional cc's by popping up a matching dome to replace the machining in the head.
But don't hold your breath, those heads look pretty thin above the combusition chamber.
Hudson
