Author Topic: Holley 750  (Read 2913 times)

Offline Bitzer!

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Holley 750
« on: April 15, 2012, 03:18:02 pm »

Hi guys,

Either a silly question, a senior moment or I have a problem!

The 454 fires up lovely on the key, I have the throttle cable hooked up to the front linkage.

The two rear barrels aren't taking juice unless I opererate the linkage manually. Am I just missing a spring or should they run on vacuum?

cheers as always

Andy
1979 GMC CrewCab  C20 1t
454 750 Holley,TH350, 14bolt diff fully floating
Why aren't there 8 days in a week!
A K5 rolling shell *new addition*

Offline ralphhemi

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Re: Holley 750
« Reply #1 on: April 15, 2012, 07:55:41 pm »
If you have a mechanical 4 barrel ,then it will be a double pumper 2 accelerator pumps , if you have vacuum secondaries  they will not open until under load     
Ralphhemi

Offline Bitzer!

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Re: Holley 750
« Reply #2 on: April 16, 2012, 11:08:08 am »

Aha that would explain it!

Yes they are vacuum, can I / is it worth it to change them over to fully mechanical?

cheers
1979 GMC CrewCab  C20 1t
454 750 Holley,TH350, 14bolt diff fully floating
Why aren't there 8 days in a week!
A K5 rolling shell *new addition*

Offline bake74

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Re: Holley 750
« Reply #3 on: April 17, 2012, 06:20:24 am »

Aha that would explain it!

Yes they are vacuum, can I / is it worth it to change them over to fully mechanical?

cheers

     It would be worth it if you want to stand there and throttle the truck to wide open to see the secondaries open.  Otherwise when you drive it you will be able to tell if they open.  They work just fine being vacuum operated as long as the vacuum hoses are hooked up and you have good vacuum.
#1: The easiest and most obvious solution to any problem is 99% of the time correct.
#2: There is no such thing as impossible, it just takes longer.
  74 k10, 77k10    Tom

Offline Bitzer!

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Re: Holley 750
« Reply #4 on: April 17, 2012, 09:41:39 am »
Cheers Bake, I guess I'll leave em as they are. All new vacuum hoses and tight fit so should be fine. One less thing to worry about!!
1979 GMC CrewCab  C20 1t
454 750 Holley,TH350, 14bolt diff fully floating
Why aren't there 8 days in a week!
A K5 rolling shell *new addition*

Offline TexasRed

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Re: Holley 750
« Reply #5 on: April 17, 2012, 09:30:55 pm »
Howdy Bitzer! Have you seen this regarding holley carbs: http://www.bob2000.com/carb.htm

Offline Bitzer!

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Re: Holley 750
« Reply #6 on: April 18, 2012, 04:28:10 pm »
Cheers TexasRed

I hadn't seen that but it's well and truely saved!!!
1979 GMC CrewCab  C20 1t
454 750 Holley,TH350, 14bolt diff fully floating
Why aren't there 8 days in a week!
A K5 rolling shell *new addition*