[DeTomaso] Initial Timming

[JDeRyke at aol.com]

In a message dated 4/26/09 7:36:46 PM, rimov at charter.net writes:
snip....
> .... Chevy or Ford have their timing around 18 degrees BTC and run around 
> 42 degrees total advance by 4200 rpm. Does this sound about right for a 
> mildly build 351c......
> 
IMHO, way too much total OR initial timing, especially on todays gasoline, 
for a normal pushrod V-8 except during light-load cruise. I run 10-12 
degrees initial and 22 degrees centrifugal in our 351C for a total of 34, with no 
vaccum advance at all. Makes starting the engine easier, too. The Cleveland 
closed-combustion chamber is very efficient and only needs about 34-36 
degrees of total ignition lead. Very late Chev LS-2, -3 and -6 engines also only 
need about the same. F-1 engines with extremely efficient combustion 
chambers currently run around 18 degrees TOTAL ignition lead.   Only old open 
chamber heads such as early '60s Hemis and flathead Fords actually run very well 
under load with that much lead. And many of those are set for drag racing. 
Are you referring to a DOHC Ford? I'd expect those to not need such timing 
either. Last engine I worked on that needed that much initial lead was a turbo 
Corvair, and it had centrifugal RETARD to keep the pistons in the 
block..... My 2¢- J Deryke


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