01-23-2017, 06:46 PM
(01-23-2017, 12:10 PM)David Luciani Wrote:(01-23-2017, 10:56 AM)Paul F Wrote: Interesting story. So what exactly did the conversion kit do?
the conversion kit basically stroked the mc5. the mc5 had a 1.375 stroke.
the mc10 got a 1.5 stroke and was so much faster mcculloch made the mc5/6 with the same 1.5 stroke.
for those with mc5's mcculloch sold a back fit kit with a stroker piston crank and thicker gaskets to allow clearancing.
ted can explain better than me as he lived that era but it made the mccullochs pretty unstoppable after that.
the interesting part was that because the mc6 and mc10 had the same stroke mcculloch sales of the mc10 were not as good as expected. soooo mcculloch then stroked the mc10 to 1.675.
the mc10 block was too short so it too had to be shimmed.
shortly after that mc20 was born with a longer block.
dave l.
The conversion kit had a thinner head gasket and a thin ring piston as well as the stroker crank. The thin ring piston was worth a ton of RPM. The Mc6 was faster than the Mc10, mostly due to the thin rings. Mac quickly realized that their "standard" engine was eating their "super" engine, and came out with the legendary 5.8 C.I. kit for the Mc10. Properly set up, the stroked Mc10's would make short work of the Mc20 when it was released. The Mc6 was king of standard A class until the Mc7 arrived. TJ