I suspect your battery / cables are marginal... I have the Concorde RG
battery and the original piper aluminum cables, in a twin which means looong
cables... My non heated engines spin just fine regardless of temperature...

I do keep the cable connections polished and greased with Dow silicone...
But the real eye opener was the Concorde RG battery... day and night
difference compared to a standard battery...
denny

"Jay Honeck" wrote in message
news:CivYb.339528$xy6.1678994@attbi_s02...
well, I've done the no-preheat thing on a 30 degree day and the prop
didn't spin all that fast (barely started). With a preheat on a
20 degree day the prop spins a lot faster.