Holley Carb Secondaries
Thread Starter
Burning Brakes
Joined: Aug 2007
Posts: 1,084
Likes: 8
From: Illinois
Holley Carb Secondaries
I have a 71 350/330hp with a stock holley 4 barrel carb. It appears my secondaries are not opening all the way. It is a vacuum 4 barrel not a mechanical. What can you do or adjust to get them to open all the way. Can you tell by looking at the diaphragmwhether it is good or needs to be replaced? Car runs fine but doesn't seem like it has the pickup--second 2 barrel not kicking in.
Le Mans Master
Joined: Apr 2006
Posts: 5,403
Likes: 95
Vacuum secondary holleys were setup from the factory with a fairly stiff vacuum can spring they did it to make sure they did not come open to quickly cause it to bog. to stiff a spring causes the secondaries to both open to slowly and can cause the carb to not even be able to pull the secondaries open all the way. HLY-20-13 is a vacuum spring kit allows you to adjust it. www.summitracing.com.
Last edited by Little Mouse; Jun 19, 2008 at 09:01 PM.
Drifting
Joined: Apr 2008
Posts: 1,540
Likes: 51
From: Lexington Park Maryland
and it could be a bind in the throttle linkage.
How do you know for sure the secondaries aren't opening ? I heard a trick is to put a paper clip on the little arm (cam) that turns when the vacume pulls and "opens" the secondaries. Then go for a WOT test ride and check to see if the paper clip moved (after you come back)...., and if so, how far it actually moved. Check the linkage first though......., with someone elses foot on the gas pedal from inside the car (motor off) while you look at the carb. Don't just "work" the throttle with your hand from the carb.
How do you know for sure the secondaries aren't opening ? I heard a trick is to put a paper clip on the little arm (cam) that turns when the vacume pulls and "opens" the secondaries. Then go for a WOT test ride and check to see if the paper clip moved (after you come back)...., and if so, how far it actually moved. Check the linkage first though......., with someone elses foot on the gas pedal from inside the car (motor off) while you look at the carb. Don't just "work" the throttle with your hand from the carb.
