timing on bbc

just wanting to know how much timing most people run on a conventional head bbc blown alky running 25-30lbs boost

 

timing

32 degrees max

 

Depends on combustion chamber and compression ratio, but 32* should be good for most combo's.

 

Ran 35* before at 45+ LBS of boost with great success. 32 is probably pretty safe. Really depends on reading the strap on the plug and going from there. Altitude will change it as the higher the altitude, the more you can run to compensate for the bad air.

 

BBC timing

32 degrees here too 11:1 static (only 30 lb boost though)

 

timing

I ran my timing at 32* 27% over making 42# 11.3 comp...

 

540 bbc, 25-30lbs boost. I started at 30 degs to get the fuel worked out, now running 35 and everything still looking real safe and clean. But most of the time I'm running in 4000 ft air or higher.

 

How much power gain is there from going from say 28-30 deg

 

Really have to qualify all amswers by the type of mag being used as well as the triggering system.

 

timing

what is the difference when not running a mag but a 7AL-3?

 

I agree. We used to run 40 degrees on a 496 with 8-71 at 45% using a Vertex mag and did very well. When we switched to Mallory 4's had to back the timing to the 30-35 range but also had 14's on at the 45%. In the 30 to 35 # boost range. JW

 

540 BBC, 14-71, 30 lbs boost. Crank trigger set a 34, after 7730 box I have 32 at the plug. Pull 4 to 10 out at the hit, depending on track conditions, no more spinning.

As for the 7AL3, not on a blower motor with any boost.

Steve

 

What about with billet heads?

14/71 Littlefield hi-helix
Supermag III

We've been running 34-35 and its not showing signs of not liking it, just looking at maximizing everything for next year

 

What is the most boost you guys have seen with a 7AL3 and HVC II coil

 

blown 540

heres my combo 540 dart 320 heads 11.25comp,oliver steel rods,7al3 box at 28 deg,10/71 hhr set back,bird,down nozzles,making 40lbs,glide,,4.10 gears 33/16.5 hoosiers.engine very happy havent leaned on it yet.1.07 on the rear tires