Hot Rod Forum : Hotrodders Bulletin Board - View Single Post - vacuum secondary or douple pumper
View Single Post
  #20 (permalink)  
Old 01-30-2013, 07:02 AM
496CHEVY3100's Avatar
496CHEVY3100 496CHEVY3100 is online now
Appalachian American
 

Last journal entry: ,
Last photo:
Join Date: Jul 2012
Location: Appalachia GA
Posts: 844
Wiki Edits: 0

Thanks: 442
Thanked 310 Times in 273 Posts
Quote:
Originally Posted by bowtie44s View Post
Hey guys, I'm sure you've answered this 100 times. I know this isn't a hot rod question so I appoligize. I have a mildly built 454, I'd guess around 400hp. It is in a heavy 1 ton truck with a 5 speed manual. I use this truck to tow a good bit and just cruise around. I have a 750 holley vacuum secondary on it now. It does pretty good for cruising but when loaded I have to get the rpms up enough for the secondaries to open. I'd rather have a douple pumper so if I push the throttle enough I can open the secondaries at a lower rpm. I tried a really light spring in the secondaries but without the pump shot it makes it bog when they open. Every place I read says you don't want a double pumper for towing but no one says why. Would it be a bad idea to switch to a dp? Also would it kill my fuel mileage? I'm getting about 11mpg empty with the vs... pretty good i think for a 6600lb truck.
put a firmer spring back in start with yellow then adjust firmer until bog goes away ,,secondarys opening to soon causing Bog ,probably end up with brown,
Reply With Quote