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:

http://www.classiczcars.com/forums/carburetors-s30/48969-weber-internal-spring.html

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)

New

713.2 N-m

526 Ft-Lbs

47605.027

Used

1,634.4 N-m

1,206 Ft-Lbs

47605.027

New

1,669.2 N-m

1,231 Ft-Lbs

47605.009

New

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 August 12, 20159 yr by Blue

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!

Ft-Lbs or In-Lbs?

Springs are now NLA from Weber so Spruell had a run of SS replacements made: http://www.spruellmotorsport.com/new-rust-proof-stainless-springs-weber-throttle-shaft-return-spring-p-3555.html

Just bought the volume deal from Spruell, 10 for $30. Unfortunately, the DCOE jets were all sold out some time ago, they said.


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