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Discussion Starter · #1 ·
i saw a post that eluded to depending on cam your initial timing could even be retarded which made think on my issue. i have a 454 30 over mid 70's vintage, it has a Herbert cam (BH2) duration int./ex. 285 @.050 248 lift int./ex. 629 cam lobe center 110* int108 that's what the sheet states in the paperwork that came with the car. it is a solid lifter, roller rockers. 750 holley, stock HEI, appears to be stock heads do not know if any work was done to them.
it starts an idles fine but would almost die when put in gear so i checked the timing and it was at 0* so i advanced it to 12* and it starts runs and idles great and in gear. i have to check to make sure that 0* is truely TDC with a piston stop so then i will know where timing really is but is not real easy to do on this car and its below freezing in my area in a non heated garage.
once i confirm TDC would you still go with 12* initial timing with the cam that's in it
i was thinking of going with a sniper but not being great with EFI i think i will stick to the holley
 

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Yes, if anything 12 is conservative with that cam. The thing that you have to consider, however, is when you start to get beyond 12 degrees static base advance you need to know what the amount of centrifugal advance is and rope that in if the total gets beyond about 34-36 degrees.

The base static timing is to get the engine to idle well. In all cases the goal is to have the burn over with by about 14-16 degrees ATDC. So the advance settings are designed to making that happen. The advance at idle covers the slow burn through a low density mixture, that is the result of engine being heavily throttled so the engine is by intent short of breath while the rotation period is relatively long in the time it’s taking to tach over. The greater advance at speed is the result of needing more time to end the burn by 14-16 degrees ATDC so while the mixture density at WOT is much greater as the cylinders are able to breath without throttle restriction and the more dense mixture burns faster it is nonetheless running short on time to perform their act.

Bogie
 

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Discussion Starter · #3 ·
Yes, if anything 12 is conservative with that cam. The thing that you have to consider, however, is when you start to get beyond 12 degrees static base advance you need to know what the amount of centrifugal advance is and rope that in if the total gets beyond about 34-36 degrees.

The base static timing is to get the engine to idle well. In all cases the goal is to have the burn over with by about 14-16 degrees ATDC. So the advance settings are designed to making that happen. The advance at idle covers the slow burn through a low density mixture, that is the result of engine being heavily throttled so the engine is by intent short of breath while the rotation period is relatively long in the time it’s taking to tach over. The greater advance at speed is the result of needing more time to end the burn by 14-16 degrees ATDC so while the mixture density at WOT is much greater as the cylinders are able to breath without throttle restriction and the more dense mixture burns faster it is nonetheless running short on time to perform their act.

Bogie
thanks Bogie that's a great explanation and helps a ton it had me concerned when i found it at 0*which seemed way off which is why i questioned the setting with that cam in it once i confirm TDC to see if the balancer is actually correct i can adjust from there and see what total timing is
 
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