holley carb not opening completely @ wot

[lambsgrace]

I was inform that my carb could be the issue after checking it is not open completely at wot. can it be adjusted I notice a set screw I think its the secondary that not opening I am sure the first set is opening completely. I am pushing a 15x17p on alpha 1. and its power is not there will the carb not opening affect my performance so severely, big changes now

 

[Don S]

Re: holley carb not opening completely @ wot

Moving thread to Other Brands, It's obviously not a Mercruiser, because they don't use Holley carbs, they have also NEVER used the 460 Ford you say you have from your other thread.
The fact that you have a 460 on an Alpha I tells me it's time for you to start posting some pictures of your engine, your drive, and your carb. http://forums.iboats.com/showthread.php?t=468676

 

[lambsgrace]

Re: holley carb not opening completely @ wot



Hello Don please forgive I really need your help I think its a 351 maybe with 460 heads here are the pic, as stated after reading your advice to others in reguards to rpms and prop issue I checked my carb and its not opening all the way I ben told not to change prop out till carb is fuctioning correctly, only one set of butterfly's are opening completely the second set towards the transom barely open can I adjust the linkage I just had a kit place in that carb that why I didn't check it

 

[fishrdan]

Re: holley carb not opening completely @ wot

That Holley has vacuum secondaries, so either the vacuum pot isn't getting vacuum, the diaphragm is ruptured or the spring is to heavy. (Or the engine isn't pulling enough vacuum to open the secondaries.) Holley has a kit for tuning the vacuum secondary, different springs. They also have a special top that allows the spring to be changed without disturbing the rubber diaphragm.


I had a holley that the vacuum pot's check ball seat didn't have a big enough "dent" in the seat to allow vacuum to draw past the check ball. (Vacuum should pull through the "dent" to open the secondaries and the check ball unseats to slam the secondaries shut quickly.) No matter what I did, the secondaries wouldn't open. I finally took a thin screwdriver, placed it on the light dent Holley made, and punched the dent deeper, the secondaries magically started working. Manufacturer's defect...............

 

[Capt Ken]

Re: holley carb not opening completely @ wot

Now that is interesting. Mercruiser hasn't used a ford engine since 77 and before Alpha drives. Oh wait, is that alpha bolted to #1 transom assembly? 460 heads aren't bolting to a small block anyway. Both the marine 302 and 351 used the 351 heads and cam.

 

[Maclin]

Re: holley carb not opening completely @ wot

Fishrdan touched on this but I want to expand it some...

The secondary buterflies will not open on that model of carb with just throttle movement with the engine not running. The linkage will close them, but will not open them. The engine's draw thru the primary barrels is used to work the vacuum pod to open the secondaries as the engine's demand increases. The spring inside the vacuum pod determines the rate of opening.