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Converting to electric choke on Holley 750DP #3093587
11/11/22 10:21 PM
11/11/22 10:21 PM
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Highland, Michigan
1972Rallye Offline OP
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I'm adding a Holley electric choke kit (for internal vacuum) to a 4779-6 750 double pumper w/ mechanical secondaries. While there is an opening in the main block that is fairly deep (1.5 inches), I dont think it has access to vacuum. There is a hole going down through the throttle plate but it does not go all the way up to the vacuum port for the choke piston. Its only about 9/16 deep into the main block. Can/should I drill this out so the ports can connect or is there another source to vacuum I'm not seeing. I've added a few pics to illustrate what I'm talking about.

By the way, the Holley Tech line guy said I MUST to use an external vacuum choke kit. I already bought this one from Ebay and opened it so I can't return it. I'd like make it work if I can.

20221109_160150.jpg20221109_160246.jpg20221109_160513.jpg
Re: Converting to electric choke on Holley 750DP [Re: 1972Rallye] #3093595
11/11/22 11:09 PM
11/11/22 11:09 PM
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in a cattle trailer down by th...
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Guitar Jones Offline
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I would go ahead and drill it, you can always block it off if it doesn't work out.


I raise chickens, so I am literally a chicken tender.

The Scamp is sold, now just two old trucks and one newer one.
'92 D250 Club Cab CTD, 47RH conversion, pump tweaks, injectors, rear disc and hydroboost conversion.
'74 W200 Crew Cab 360, NV4500, D44, D60 and NP205 divorced transfer case.
2019 1500 Long Horn Crew Cab 4WD, 5.7 Hemi.
Re: Converting to electric choke on Holley 750DP [Re: Guitar Jones] #3093830
11/12/22 09:56 PM
11/12/22 09:56 PM
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Omaha Ne
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Originally Posted by Guitar Jones
I would go ahead and drill it, you can always block it off if it doesn't work out.


I'd agree, do make sure to use a gasket ( usually cork) in the recess to seal the port. wink

Re: Converting to electric choke on Holley 750DP [Re: TJP] #3093894
11/13/22 09:30 AM
11/13/22 09:30 AM
Joined: May 2005
Posts: 1,617
Apollo, PA.
B1MAXX Offline
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You got the wrong hole targeted its one of the lower plane ones and holley makes a a little spacer to bring it up the the housing height.

the one up and left from the one your looking at

Last edited by B1MAXX; 11/13/22 09:32 AM.
Re: Converting to electric choke on Holley 750DP [Re: B1MAXX] #3093907
11/13/22 10:24 AM
11/13/22 10:24 AM
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Originally Posted by B1MAXX
You got the wrong hole targeted its one of the lower plane ones and holley makes a a little spacer to bring it up the the housing height.

the one up and left from the one your looking at

I was wondering about that but since I don't have one in my hand I wasn't sure.


I raise chickens, so I am literally a chicken tender.

The Scamp is sold, now just two old trucks and one newer one.
'92 D250 Club Cab CTD, 47RH conversion, pump tweaks, injectors, rear disc and hydroboost conversion.
'74 W200 Crew Cab 360, NV4500, D44, D60 and NP205 divorced transfer case.
2019 1500 Long Horn Crew Cab 4WD, 5.7 Hemi.
Re: Converting to electric choke on Holley 750DP [Re: B1MAXX] #3093911
11/13/22 10:39 AM
11/13/22 10:39 AM
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Omaha Ne
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Originally Posted by B1MAXX
You got the wrong hole targeted its one of the lower plane ones and holley makes a a little spacer to bring it up the the housing height.

the one up and left from the one your looking at

Hmm, never seen a spacer shruggy But you may be right ?
In the pictures provided it's hard to see which holes line up when the choke is mounted. confused FWIW: The hole with the brass restriction is the one that needs the manifold vacuum source. beer

Re: Converting to electric choke on Holley 750DP [Re: Guitar Jones] #3093913
11/13/22 10:44 AM
11/13/22 10:44 AM
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Apollo, PA.
B1MAXX Offline
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Its been forever so I am going by memory,

Re: Converting to electric choke on Holley 750DP [Re: TJP] #3093915
11/13/22 10:45 AM
11/13/22 10:45 AM
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Originally Posted by TJP
Originally Posted by B1MAXX
You got the wrong hole targeted its one of the lower plane ones and holley makes a a little spacer to bring it up the the housing height.

the one up and left from the one your looking at

Hmm, never seen a spacer shruggy But you may be right ?
In the pictures provided it's hard to see which holes line up when the choke is mounted. confused FWIW: The hole with the brass restriction is the one that needs the manifold vacuum source. beer


yes

Ill look in a minute when I go out to the shop

Last edited by B1MAXX; 11/13/22 10:49 AM.
Re: Converting to electric choke on Holley 750DP [Re: B1MAXX] #3093929
11/13/22 11:26 AM
11/13/22 11:26 AM
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Apollo, PA.
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Ok I 'm going to delete my original post the original poster has the right hole...... the one I referenced is for the vacuum sec. on the main body I checked that hole, that the original poster shows is drilled straight through to the center cavity.

Re: Converting to electric choke on Holley 750DP [Re: B1MAXX] #3093930
11/13/22 11:30 AM
11/13/22 11:30 AM
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B1MAXX Offline
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Now I have to figure out what combination takes the spacers. work

Re: Converting to electric choke on Holley 750DP [Re: B1MAXX] #3093941
11/13/22 12:15 PM
11/13/22 12:15 PM
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Highland, Michigan
1972Rallye Offline OP
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Originally Posted by B1MAXX
Ok I 'm going to delete my original post the original poster has the right hole...... the one I referenced is for the vacuum sec. on the main ody I checked that hole, that the original poster shows is drilled straight through to the center cavity.


That's exactly what I needed to know. I wasn't sure if it connected the the lower hole in my second pic to form an L-shaped passage or went straight through to the center. Thanks!

Re: Converting to electric choke on Holley 750DP [Re: 1972Rallye] #3093997
11/13/22 05:31 PM
11/13/22 05:31 PM
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yep sorry for the confusion.

Re: Converting to electric choke on Holley 750DP [Re: 1972Rallye] #3094033
11/13/22 08:44 PM
11/13/22 08:44 PM
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Originally Posted by 1972Rallye
Originally Posted by B1MAXX
Ok I 'm going to delete my original post the original poster has the right hole...... the one I referenced is for the vacuum sec. on the main ody I checked that hole, that the original poster shows is drilled straight through to the center cavity.


That's exactly what I needed to know. I wasn't sure if it connected the the lower hole in my second pic to form an L-shaped passage or went straight through to the center. Thanks!


L shaped as straight through would be above the throttle blades giving you "venturi" or ported vacuum versus manifold vacuum which is what is needed for the choke to function properly beer

Don't forget the gasket ( usually cork) to seal that passage when mounting the assembly

Last edited by TJP; 11/13/22 08:46 PM.
Re: Converting to electric choke on Holley 750DP [Re: TJP] #3094069
11/14/22 07:26 AM
11/14/22 07:26 AM
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No straight through to the center cavity, between the the two barrels. up

that being said you better go straight, or you will end up in the barrel.

Re: Converting to electric choke on Holley 750DP [Re: B1MAXX] #3094126
11/14/22 12:07 PM
11/14/22 12:07 PM
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Originally Posted by B1MAXX
No straight through to the center cavity, between the the two barrels. up

that being said you better go straight, or you will end up in the barrel.


You might be right as I was ASSuming spank and did not have a carb in front of me spankspank Thanks for clarifying. beer







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