DeTomaso Mailing List: June 99, Message #71

In a message dated 6/3/99 8:24:25 PM Eastern Daylight Time, WVillere@AOL.COM 
writes:

<< I just got back from making 3 pulls on a Dynojet in Rohnert Park.  All 3 
 pulls were within 5 hp of each other.  Peak HP was 297 at 5,250.  It 
 immediately dropped off to 277 by 5500, but then back up to 297 by 5750 
(same 
 drop on all pulls). >>

Walter,

Well, it could be a couple of things, but I would immediately suspect the 
carb. What happens are the secondaries are opening up, and you are getting a 
lean condition for an instant. With the vacuum secondaries, there is no burst 
of fuel to accommodate the additional air flow. There are a couple of ways to 
check this...one is to look at the corresponding fuel number within that RPM 
range. It should be in the .51 to .55 range..If it drops to, lets say, .46 
then you've found your problem. You can change the spring in the secondary 
pot..You can change the spring either way, lighter or stiffer. If you go to a 
lighter spring, and the HP peak drops at a lower rpm, then that is the 
problem, once again...and vice versa, if you go to a heavier spring, and the 
rpm shift goes up, then that's it.

As it goes, anyway,..5500 RPM is just about the limit for that carb. I can 
easily guarantee that you will get at least 20 easy HP with a carb change. 
You didn't say if that was at the rear wheels, it looks like it may be, since 
the HP numbers are kind of low, for a direct hook up. So, the spring test is 
probably the only option open to you, unless you have a friend that has any 
type of other carb. It really doesn't matter much what kind it is, just as 
long as your engine will be able to rev to 5500 RPM.....

Regards............Gary