[Fot] Advance BTDC for 1296 Spit?

[Greg Hilyer]

Hi Bud,
I can’t speak to a 12.5 1296 but I can speak to tuning for altitude. I do a fair amount of dyno tuning at 5500’ here in Albuquerque. Be it a 40hp Formula Vee or a 500hp V8, if the engine was properly timed at sea level I’ll usually end up 4-5 degrees advanced from where it was. I’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 doesn’t lie.
People seem to think it’s expensive but that’s really not the case - maybe my dyno guy treats me exceptionally well, but I can get two “base-line” pulls for $40 (and sometimes that’s all I’ll do for the session) and rarely over $150 for extensive tuning (8-10 pulls. 
My $.02 worth,
Greg “Lunker” Hilyer 
Albuquerque NM

> On Nov 21, 2020, at 11:42 AM, Bud Rolofson via Fot <fot at autox.team.net> wrote:
> 
> Listerati,
> 
> I’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 doesn’t knock on WOT. I’m not sure I’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?
> 
> I’m running 36 degrees total advance @ 3000 RPM for a 12.52 compression engine and that’s worked pretty good so far. But I’m always looking to get out of the corners faster yet pull hard in the straights sooo……??
> 
> Thanks
> Bud Rolofson
> 
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