Holley 4150 Quality issues - Nova Tech
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  #1  
Old Dec 18th, 19, 02:32 AM
Magnus Magnus is offline
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Default Holley 4150 Quality issues

Hey everyone

I am currently tuning my Holley (80531) with Electrical Choke and Vacuum Secondaries.

I am using tach, vaccum guage to manifold, wideband lamda for AFR and I was running lean out of steady state crusing and didn't respond to 2 jets up on primaries and secondaries. I started looking at the vacuum secondaries and as I am taking of the housing I noticed where the vacuum housing passage connects to the main body (cork gasket) there was a brass bleed that was jammed in there, sideways. I guess some factory worked just couldn't care and just torqued down on the screws without noticing.

So I am going to call Holley tomorrow and see what they say, but I am way out of warranty, so I am looking to score the correct fresh brass bleed and correctly mount that, and get it back together.

Does anyone know what the purpose is and if it sits in the main body or in the vacuum housing passage? And what the spec could be on the bleed?







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  #2  
Old Dec 18th, 19, 10:25 AM
Big Dave Big Dave is offline
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Default Re: Holley 4150 Quality issues

That is a standard press-in brass air jet for the metering bloc. It mixes air with gas in the emulsion tubes inside the metering block to correct the air fuel mixture to meet demand based upon vacuum signal. I assume that is an extraneous part that jot picked up accidentally in the assembly process as your carb wouldn't run at all without one being pressed in place to meter air flow.

High performance carbs have adjustable air bleeds that thread into the top of the carb instead of being pressed in because people who have high performance engines think they have to have a rough idle (bigger cam duration than they actually need) to be a real high performance engine. That long cam duration changes the vacuum signal to the carb so that it will run pig rich unless the air bleed is changed to compensate.

You are right that is a factory defect and I am sure despite being out of warranty it will be covered by Holley (they have in the past when shown similar evidence of their making a mistake). They stand behind their product so far as the mistakes that they make go (they won't fix your mistake if you go to drilling bigger holes or breaking, such as a base plate, or warping parts such as metering blocks because you don't use a torque wrench).

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Old Dec 18th, 19, 06:46 PM
Magnus Magnus is offline
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Default Re: Holley 4150 Quality issues

I couldn't get a hold of the Holley reps today, but will try again.

So Dave, you are thinking that was just placed there by mistake? I have been Googling the web trying to figure out if there are restrictors in place, in the main body to vacuum housing passage, but can't find anything specific.

The article linked here has some good stuff about that part of the design, under the Vacuum Secondary Function section.

https://www.musclecardiy.com/perform...bration-guide/

The check ball in the vacuum housing smoothens out the rate of opening of the secondaries, so if there was a restrictor in the passage it would effect that I guess.

But you are pretty confident that there isn't supposed to be any restriction there, and it was a mistake, so removing mangled brass bleed is the right course of action, and just mount the housing back on with the gasket?

Thanks and merry xmas!
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Old Dec 18th, 19, 06:55 PM
Big Dave Big Dave is offline
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Default Re: Holley 4150 Quality issues

There is no restrictor in the vacuum line to the secondary diaphragm. The check ball is a blow out protector for the power valve that was added after racers starting modifying their Holleys for years before Holley did it.

If you can get the gasket to seal then I would use it. That ding in the body looks like it might be a potential leak.

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Old Dec 18th, 19, 08:04 PM
62 NovaWagon 62 NovaWagon is online now
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Default Re: Holley 4150 Quality issues

Yep, looks like an idle restriction tube or an air bleed and it ain't supposed to be there, the diaphragm housing may be ok but the body is messed up, I'd just clean the hole and put some JB weld or Epoxy on there and sand it down smooth for a good seal.. The check ball in the housing is to prevent the diaphragm from opening too quick, the PV blow out check ball is in the base plate.
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Old Dec 18th, 19, 11:26 PM
Magnus Magnus is offline
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Default Re: Holley 4150 Quality issues

Thanks for the quick replies!

I agree on the marring (also the body has a some casting flashing), I will try and clean it up to get a good seal, once I have chatted with the Holley reps.
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Old Dec 19th, 19, 06:22 PM
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Default Re: Holley 4150 Quality issues

Spoke to Holley, apparently this specific carb has a restrictor in that passage, that is the one that got stuck sideways on installation, they are gonna get back to me with an update how to sort it out.
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Old Dec 19th, 19, 11:08 PM
62 NovaWagon 62 NovaWagon is online now
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Default Re: Holley 4150 Quality issues

Must something new, never heard or seen any vacuum secondary with a restriction there.
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Old Dec 20th, 19, 09:02 AM
Big Dave Big Dave is offline
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Default Re: Holley 4150 Quality issues

Quote:
Originally Posted by 62 NovaWagon View Post
Must something new, never heard or seen any vacuum secondary with a restriction there.
Me neither. Usually you control the opening rate by changing the Secondary Diaphragm Spring (Holley Kit Number 20-13) in the vacuum diaphragm. I recommend buying the Quick Change Cover (Holley Part Number 20-59) so you can change the spring rate often and easily without tearing the Secondary Diaphragm (Holley Part Number 134-4) inside.

https://www.holley.com/products/fuel...ts/parts/20-59

https://www.holley.com/products/fuel...ts/parts/20-13

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Old Dec 20th, 19, 09:06 AM
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Default Re: Holley 4150 Quality issues

Best thing they came out with is that quick change cover.
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Old Dec 20th, 19, 03:34 PM
Magnus Magnus is offline
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Default Re: Holley 4150 Quality issues

You two were both right, and the rep was initially wrong. He got back to me today and said that there was not supposed to be any restriction in there.

Dave, I was about to put on the quick change cover to start experimenting with the diaphragm springs, when you found this hiccup.

Now I just need to find some time to get back in the garage! I will report back later on the tune if I get stuck.

Merry xmas!
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