Hi Bud,
I canâ??t speak to a 12.5 1296 but I can speak to tuning for altitude. I do a
fair amount of dyno tuning at 5500â?? here in Albuquerque. Be it a 40hp Formula
Vee or a 500hp V8, if the engine was properly timed at sea level Iâ??ll usually
end up 4-5 degrees advanced from where it was. Iâ??ll go up 2 degrees per pull
until the power goes backwards and then set it for peak power minus maybe one
degree for safety sake. The one caveat is to remember to dial it back when
going to the lowlands!
Starting at 48(!) degrees and backing down sounds like a recipe for disaster.
Must be hell on starters too - if it will even crank over with that much timing.
A chassis dyno is your friend and doesnâ??t lie.
People seem to think itâ??s expensive but thatâ??s really not the case - maybe
my dyno guy treats me exceptionally well, but I can get two â??base-lineâ??
pulls for $40 (and sometimes thatâ??s all Iâ??ll do for the session) and rarely
over $150 for extensive tuning (8-10 pulls.
My $.02 worth,
Greg â??Lunkerâ?? Hilyer
Albuquerque NM
> On Nov 21, 2020, at 11:42 AM, Bud Rolofson via Fot <fot@autox.team.net> wrote:
>
> Listerati,
>
> Iâ??m curious what total advance you Spifire racers are using @3000-4000 RPM
> and up?
>
> I had someone in New Mexico swear that he runs 48 degrees @4000 RPM and backs
> down by 2 degrees until it doesnâ??t knock on WOT. Iâ??m not sure Iâ??m brave
> enough to run that much advance.
>
> What say you list? What total advance are you running at what RPM. And what
> compression ratio?
>
> Iâ??m running 36 degrees total advance @ 3000 RPM for a 12.52 compression
> engine and thatâ??s worked pretty good so far. But Iâ??m always looking to
> get out of the corners faster yet pull hard in the straights sooo��??
>
> Thanks
> Bud Rolofson
>
> Extreme Parts Racing (more than just a haircut)
>
> 71TR6 CC57365 (Good 6)
> 71 Spitfire MK IV Race Car #3
> 69 Spitfire MK III (back up FE engine/dinghy car)
> 93 Minnie Winnie Race Support Vehicle
> 77 Z-50A Hardly Davidson Honda Mini-Trail Bike (Triumph Pit Bike)
>
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