[Spridgets] DCOE 40 or DCOE 45?

[WeslakeMonza1330 at aol.com]

In a message dated 27/04/2010 20:03:38 GMT Daylight Time,  
WeslakeMonza1330 at aol.com writes:

Hi John,
 
Jetting data from dyno testing on its way to you 'For Your Eyes Only'  (I'm 
ex military!).
 
I'm not certain if some UK A-series racers use a 48 DCO (48 DCOE is  
obsolete) with 42mm chokes.  If you can find a 48 DCOE it can be choked  down to 
40mm.
 
One very respected UK racer had done some machining work so he could get  
42mm chokes into a DCOE 45.
 
What I don't see much of is the use of Full Radius rams which make a big  
difference on how the DOCE pulls from low rpm.  I also don't see many CV  
exhaust systems on road cars.
 
I drive slower than I used to.  The current engine is particularly  strong 
from 5000 to 5500 rpm which on 3.9 diff and a five speed is 100 - to  about 
112mph.  If I'm driving at 4000rpm which is about 80mph in 5th and  need to 
change to the outside lane to over take I EXPECT to accelerate to  4,500 rpm 
and 90mph pretty much straightaway and without changing down to  4th.
 
The engine will pull smoothly from about 2000 rpm in 4th (on a 3.9 diff)  
even if the throttle is floored and I think I showed Frank this when he was 
in  the UK though it may have been slightly higher rpm (2300?) as that engine 
was  near the end of its life (though managed to haul the car to 105mph+ 
the week  before I pulled it to fit the new engine).
 
With a controlled vortex manifold from Janspeed and Full Radius rams on  
any Spridget with a DCOE, and especially a street car you'd soon be on the  
phone ordering some bigger rams as the engine would pull like a train but feel 
 asthmatic going through 6000rpm.
 
In early days of ownership my Sprite had a 4.5 diff and a 4 speed so  
110mph was 7,500rpm and seen on a regular basis on weekends.  I was much  younger 
then.
 
Regards
 
Weslake-Monza 1330
 
In a message dated 27/04/2010 19:43:34 GMT Daylight Time,  
fastvee at yahoo.com writes:

I know that different size choke tubes can be made to  work in the same 
carb body with different jetting combinations, but  many 1275 race engines use 
smaller venturis than that, so I am  surprised. Our definition of road going 
must be vastly different, and  your choice would not be the best choice for 
my street driving. I  drive fast, but for me road going means 2000-5000 
rpm, with much more  time under 4500 than above it, and where mixture quality 
and smooth  transition from idling to the main circuit trumps the last bit of 
 airflow any day. I would be interested to see your dyno  sheets.
John
Fogelsville,  PA