Holley 4150 electric choke with mech secondaries issue - Team Camaro Tech
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post #1 of 14 (permalink) Old Dec 3rd, 16, 07:42 PM Thread Starter
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Holley 4150 electric choke with mech secondaries issue

I ordered an electric choke kit to install in my Holley 850 (4150 4771). I installed one in my 750 and it was pretty easy. The only real difference between these two carbs is that the 750 was vacuum secondaries and my 850 is mechanical.
There are three problems I ran into with the 850. 1. I had to remove a vacuum port that was in the way. Not a big deal, but I was surprised I needed to. 2. I had to manipulate the choke rod quite a bit to get it to work. Again, was able to make it work. 3. The last thing is what I need to figure out. The mechanical secondaries are hitting the choke housing and won't let them open completely. All this makes me think it's the wrong kit, but I haven't seen one that mentions mechanical or vacuum secondaries. Anyone else run into this? What did you do about it?

'69 SS396 X66 L34 08D M21 BS
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post #2 of 14 (permalink) Old Dec 4th, 16, 08:37 AM
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Re: Holley 4150 electric choke with mech secondaries issue

I recently converted my Holley 660DP to an electric choke and had zero difficulties. Didn't have to make any mods. I am not aware of a different electric choke conversion for Holley carbs.


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post #3 of 14 (permalink) Old Dec 4th, 16, 08:38 AM
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Re: Holley 4150 electric choke with mech secondaries issue

Generally, performance models, i.e., mechanical secondaries, use the manual choke.
Picture of interference?

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post #4 of 14 (permalink) Old Dec 4th, 16, 12:55 PM Thread Starter
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Re: Holley 4150 electric choke with mech secondaries issue

Quote:
Originally Posted by caldrovp View Post
I recently converted my Holley 660DP to an electric choke and had zero difficulties. Didn't have to make any mods. I am not aware of a different electric choke conversion for Holley carbs.


Vince
Yes, the 660 style is easy. Vacuum secondaries right? Different carb. I've installed these kits before and there's not much to it. I'm looking for experience with mechanical secondaries only.

Quote:
Originally Posted by Everett#2390 View Post
Generally, performance models, i.e., mechanical secondaries, use the manual choke.
Picture of interference?
Thanks Everett. The manual choke is what I was afraid of. I don't want manual. I might modify the housing on this one. It only hits by a small amount. Here are a couple of pics. I would have posted them before, but Flickr doesn't have the right option to share pics with their android app... I had to boot up my laptop.

Better to have too many pics than not enough right? lol...

1st thing, here are a couple of pics before and after I recon'd my carb. Evaporust is great.






Finally, here are the issues.



Vacuum tube removed. To be plugged.



Secondaries idle position. Notice relation to the brass fittings threads.



Secondaries opened all the way.




Here you can see what is happening. The butterflies aren't quite open all the way.






Any reason you can see for not cutting off the vent before the threads? I've never seen that part used anyhow. All I'll need to do is put a small piece of filter in where I cut it off. It's part of a PCV style system. I have to hook it up to a vacuum source because it's not a vacuum secondary carb.


'69 SS396 X66 L34 08D M21 BS
460ci Gen VI 9.75:1 AED 950 carb
241/249 @ .050" .625/.625 110 LSA

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post #5 of 14 (permalink) Old Dec 4th, 16, 02:05 PM
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Re: Holley 4150 electric choke with mech secondaries issue

Cut it off and move on

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post #6 of 14 (permalink) Old Dec 4th, 16, 07:41 PM
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Re: Holley 4150 electric choke with mech secondaries issue

The threaded vent has tubing going to the heat stove in assisting heat. Otherwise, a wire filter gets installed filtering the air.
The vacuum port in the carb body is opened up for the piston on the right side as vacuum pulls on the piston and piston pulls against the cap spring in the controlled opening of the choke.
Opening up the secondaries any more is not going to do anything more - your Seat-O-Pants meter won't peg any more.
Adjust the linkage on drvr side so the primaries are fully opened and secondaries are rested against the vent.
Or, you could grind away a portion of the cam retained with the screw in clearancing the vent.

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post #7 of 14 (permalink) Old Dec 4th, 16, 10:47 PM
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Re: Holley 4150 electric choke with mech secondaries issue

Isn't it just a breather to eliminate condensation in the housing ? Not related to the PCV system. The older conversion housing don't have the screen and fitting. Here's one I've had with very little use, I tried to sell a few times here....still for sale. The pics don't show it well, but there's just small open port there, about 3/8" OD maybe less, instead of the fitting and screen.




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Last edited by Garfields Maro; Dec 4th, 16 at 10:59 PM.
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post #8 of 14 (permalink) Old Dec 4th, 16, 11:12 PM
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Garth
 
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Re: Holley 4150 electric choke with mech secondaries issue

oops, the choke pictured above came off a 670 Street Avenger. The housing is the same as the one in the conversion kits, except the breather port.

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post #9 of 14 (permalink) Old Dec 5th, 16, 06:38 AM Thread Starter
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Re: Holley 4150 electric choke with mech secondaries issue

Quote:
Originally Posted by 1971ls6 View Post
Cut it off and move on
That' what I'm going to do.

Quote:
Originally Posted by Everett#2390 View Post
The threaded vent has tubing going to the heat stove in assisting heat. Otherwise, a wire filter gets installed filtering the air.
The vacuum port in the carb body is opened up for the piston on the right side as vacuum pulls on the piston and piston pulls against the cap spring in the controlled opening of the choke.
Opening up the secondaries any more is not going to do anything more - your Seat-O-Pants meter won't peg any more.
Adjust the linkage on drvr side so the primaries are fully opened and secondaries are rested against the vent.
Or, you could grind away a portion of the cam retained with the screw in clearancing the vent.
Are you sure about the heat stove assist? I thought it was just to eliminate condensation? I don't doubt you, I just didn't know. God forbid Holley explains it clearly in the instructions...
I'm not sure I understand what you were saying about the vacuum port in the carb body in reference to the piston. Can you elaborate a little?
I hear you on the SOP meter, but I just want it to open all the way. At this point, I'm planning on modifying the choke housing.

Quote:
Originally Posted by Garfields Maro View Post
Isn't it just a breather to eliminate condensation in the housing ? Not related to the PCV system. The older conversion housing don't have the screen and fitting. Here's one I've had with very little use, I tried to sell a few times here....still for sale. The pics don't show it well, but there's just small open port there, about 3/8" OD maybe less, instead of the fitting and screen.
I wasn't saying it was hooked to the PCV system. I was just saying it was like a PCV system where it's hooked to a vacuum source on one side and a filter on the other. Like you, I thought it was to pull out condensation. Everett seems to really know his stuff and he said it's really for a heat assist.
PM me what you're looking to get out of the choke. I'd like to have a spare. I'm always messing around with carbs. Also, if you're doesn't have the threads in the way I'd love to use that one instead of modifying mine.

'69 SS396 X66 L34 08D M21 BS
460ci Gen VI 9.75:1 AED 950 carb
241/249 @ .050" .625/.625 110 LSA

Semper Fi!

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post #10 of 14 (permalink) Old Dec 5th, 16, 09:27 AM
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Re: Holley 4150 electric choke with mech secondaries issue

in the 3rd, pic it looks like there is a crack where one of the lower float bowl screws thread into the housing. I don't know if I'd trust that.

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post #11 of 14 (permalink) Old Dec 5th, 16, 11:40 AM
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Re: Holley 4150 electric choke with mech secondaries issue

Quote:
Originally Posted by DenRS View Post
in the 3rd, pic it looks like there is a crack where one of the lower float bowl screws thread into the housing. I don't know if I'd trust that.
Looks more like casting flash than a crack, to my eyes.

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post #12 of 14 (permalink) Old Dec 5th, 16, 12:03 PM Thread Starter
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Re: Holley 4150 electric choke with mech secondaries issue

Quote:
Originally Posted by DenRS View Post
in the 3rd, pic it looks like there is a crack where one of the lower float bowl screws thread into the housing. I don't know if I'd trust that.
Quote:
Originally Posted by dyno jonn View Post
Looks more like casting flash than a crack, to my eyes.
Good catch Den, but like John said, it's just casting flash and a shadow.

And just for the record... I just noticed I called my carb a 4771. It's a 4781.

'69 SS396 X66 L34 08D M21 BS
460ci Gen VI 9.75:1 AED 950 carb
241/249 @ .050" .625/.625 110 LSA

Semper Fi!

"The galleries are full of critics. They play no ball, they fight no fights. They make no mistakes because they attempt nothing."
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post #13 of 14 (permalink) Old Dec 10th, 16, 06:38 PM
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Re: Holley 4150 electric choke with mech secondaries issue

Do not cut the choke housing. The mechanical secondary carbs require a new style pump cam bracket with a notch machined in it to clear that boss on the choke housing. I don't have the part number handy but if you need it I'll find it for you.

2nd, mechanical secondary carbs use a choke kit with a tiny vacuum nipple coming from the lower front portion of the housing to draw vacuum for the choke mechanism since the passage isn't drilled in the body like it is on a vacuum secondary carb.

If you can't get a handle on this, give me a call next week and I'll try to walk you through it.

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post #14 of 14 (permalink) Old Dec 11th, 16, 08:08 AM Thread Starter
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Re: Holley 4150 electric choke with mech secondaries issue

Quote:
Originally Posted by Vintage Musclecar View Post
Do not cut the choke housing. The mechanical secondary carbs require a new style pump cam bracket with a notch machined in it to clear that boss on the choke housing. I don't have the part number handy but if you need it I'll find it for you.

2nd, mechanical secondary carbs use a choke kit with a tiny vacuum nipple coming from the lower front portion of the housing to draw vacuum for the choke mechanism since the passage isn't drilled in the body like it is on a vacuum secondary carb.

If you can't get a handle on this, give me a call next week and I'll try to walk you through it.

Eric
Awesome Eric. Thanks for the info. I have the mechanical secondaries choke housing with the different vacuum nipple. I'll see what I can find for the different cam. I'll pm you if I can't find it

'69 SS396 X66 L34 08D M21 BS
460ci Gen VI 9.75:1 AED 950 carb
241/249 @ .050" .625/.625 110 LSA

Semper Fi!

"The galleries are full of critics. They play no ball, they fight no fights. They make no mistakes because they attempt nothing."
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