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DCOE Throttle Spring Testing

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The Spruell Motorsport shipment just arrived with the stronger Weber 40 DCOE Throttle Springs. These springs are used to firmly close the throttle plates shut. This ensures consistent performance as explored and discovered in this thread:


For reference, here are the Weber part numbers:

47605.012 Weaker

47605.027 Standard

47605.009 Stronger

I decided to measure the spring constants of the springs I had on hand for reference:

?????????? (is from Pierce Manifold sold as 47605.009 BEWARE)


713.2 N-m

526 Ft-Lbs



1,634.4 N-m

1,206 Ft-Lbs



1,669.2 N-m

1,231 Ft-Lbs



2,203.7 N-m

1,625 Ft-Lbs

  • I am not sure of the age of the used standard spring but it has not aged much.
  • Clearly Pierce sent the incorrect spring.
  • The stronger .009's are ~ 33% stronger
Edited by Blue

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Dr.240z and I swapped in the new stronger springs in his triple 40DCOE set up.


We were able to swap them with the carbs on the car (just removed the top carb plate). A small screw driver and long needle nose pliers were the only tools needed.


It certainly closed the 3 throttle plates to the same location as repeated idle measurements were ~ 935 +/- 5 rpms.


No increase in pedal pressure was noted.


It did the trick!

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