Holley choke horn removal?

I am definitely picking up a stub stack, and may hold off on the cutting based on some info a member sent me. I'll probably remove the choke assembly though, since that change is easily reversible.
I've looked at the carb spacers initially to give me a full manifold vacuum port to run my vacuum advance off of, since I've doen a lot of reading into thwy this is a bettr setup than ported vacuum. There's many different styles, and I don;t know which one I should use.

 

I've been hearing alot about that lately... It seems funny to me 'cause I never had a problem with the two I bought.. Then again, I took them apart to see all the goodies those carbs have.. Plus I've added my own goodies to them... Rear jet extentions and notched floats from Holley.. Etc, etc..

 

I tried a 650 Road Demon on my engine and it didn't like it.
So I've had a 600 Holley, 650 Road Demon, 750 Race Demon and a 670 Holley Street Avenger on my mill, and the 670 Holley has worked the best, by a pretty noticeable margin. I'm convinced a Holley can be made to work well on anything.

 

Cool site! I saved this so I could read up on it later on... Thanks!!

 

There's a lot of cool videos to watch on there as well.

 

Look closely at this. Compare the second line of test two, the second line of test 3, and the second line of test 5, it will tie in with the pm I will send you later today.

 

I can't watch any videos with my crappy msntv 2 web box.... DAMN IT!! I gotta get a real pc once I get back to work.. And learn how to use one..

 

In the past, I've ordered Holley carb tuning kits from Summit.. accelerator pump tuning kit which gives you a shit load shooter sizes and and different pump cams and another kit that gives you different power valve sizes and jets with a shit load of fuel bowl and metering block gaskets... If you have a Summit catalog, you might want to look into it... There's also a secondary spring kit for those vacuum secondary carbs and also the quick change tops for the vacuum housing...

 

I'm seeing the K&N filter reducing flow?
Not surprising, won't every filter do the same?

 

I've seen those. I have a jet kit and the Street Avenger already has the quick change secondaries.
I don't have much knowledge beyond jet changes, I've taught myself so far. This is the first carbed engine I've really tweaked on, everything else was injected. I've had other carbed cars, just never messed with the carbs much.

 

well, yes, but theres more...

 

Got a vacuum gauge??? If not, go too your local Sears store in the tool department and buy the Craftsman vacuum gauge.. It's the one I use for balancing out the idle mixture.. I don't think it comes with a 1/8" id vacuum line.. You could buy a 3 foot long piece at your local parts store for dirt cheap or get some at a junk yard from a 70's car that has "miles" of the stuff under the hood..

 

I do, that's how I got to where I am now. I'm only getting about 10" of vacuum at idle, so I just tune it to where I get the highest idle with the mixture screws, then adjust the butterflies accordingly.

 

Yep! You got it!!

 

"So I'm thinking mill the horn, put a stub stack on it, install the air gap intake and possibly play with the jetting".



I'm a bit confused by this statement. My understanding is the stub stack is for smoothing air flow into the carb that STILL HAS the choke horn. If the choke horn HAS been removed, using the stub stack is pointless.

My line of thinking is that "every little bit helps" BUT to a point. Is there a benefit to running an aluminum RPM intake over a factory cast iron piece? Absolutely (better design, much lighter weight, accepts Holley style baseplates without an adapter). Is there a benefit to installing an AirGap when you already have a std RPM intake? Not the way I see it. As for the carb ... removal of the choke horn can be done at home for virtually nothing cost wise, and there WILL be a benefit ... whether your ass feels it or not.

 

My Advice:

Get on a dyno and quantify your data. That's the only way to know for sure. Make sure the dno guys know a bit about tuning. I know a little, but I know nothing compared to the guy that helped me. You'll spend a fortune chasing your tail unless you get the numbers to let you know what you're doing is helping. I would guess a dyno session costs less than guessing.
That's been my experience.

Good Luck!

 

Well, I decided to leave the choke horn in place, possibly remove the choke plate, add a stub stack and install the air gap. i've seen a solid 10hp gain reported through google searches over the standard rpm, plus i got it dirt cheap, plus it just looks cooler.

There are some dyno guys locally I have used before, just not sure of their carb tuning prowess.

Thanks for all the input guys, I really appreciate it!!

 

Yep! I thought this thread was great... I learned something new here today..

 

They make stub stacks for holleys WITH or WITHOUT choke horns... So cut off your horn and add the correct stub stack, no need to bother with all that messy epoxy !

 

I also have a Street Avenger and I was wondering which Stub Stack fits it? I was considering getting one of these as well.

 

The 2 BG carbs I have is the "Gold Claw" 795cfm carb and the 650 Speed Demon.... Both are double pumpers.. Plus I have a 850 center squirter (List-4223) a new Holley 800 DP list-4780 that I got for rebuilding an original L-79 Holley, a 4776 600 DP, a 4777 650 DP, a couple of 3310's 750 vac/sec and a shit load of 600 cfm carbs with vac/sec... I also have a 780 with vac/sec. that came off a 70 LS-6 454 Chevelle SS... It's a 4-speed carb with emissions... Another carb I have, has small primary throttle bores and large secondary bores but it's not a spreadbore Holley that used the quadrajet bolt pattern.. It has the standard Holley pattern.. I think it's rated at 725 or 735 cfm... It would make a great street n' strip carb for the right motor.. I have another Holley that's really wierd... This one has twin choke towers and came from the factory on the '64 390 Ford T'birds... It's way smaller than a 600... Probably a 525 cfm carb... I got a bunch more that I can't think of at this moment...

 

K&N 85-0200 is what you need.

 

I never really get the chance to collect parts, I have to sell the old stuff to buy new stuff.

 

Yup, thats about the size of it...

 

You can tune a vac secondary to work as good as a dbl pumper, but you have to dig into the thing to do it. I always liked the 3310 series for street use. I remove the choke flapper to keep it from becoming a PITA, but leave the horn itself.

 

What are you guys filling the choke blade shaft holes with?

 

do you mean the holes in the side of the choke horn? Nothing, I wouldn't bother.
I epoxy a piece of brass on the underside of the hole at the base of the air cleaner flange flange where the rod passes through.

 

Yep! I love those two!! It's all about how you want to set it up... I also like the idea of having a secondary metering block instead of a metering plate (which were only made to keep costs down) When GM and Ford were running Holleys on their high performance cars, they used a secondary metering block on all their vacuum secondary carbs.. I'm not totaly sure about the L-79 Vette/Nova carb though, And I rebuilt one for a buddy of mine not long ago.. .. Well anyway, you could always play with the secondary spring rate with those carbs.. Holley made it easy for us when they introduced the quick change top for the vacuum pod back in the '70's along with the spring kit that consists of about 7 different springs to taylor when you want the rear throttle plates to kick in.. Folks that don't know any better go for the lightest spring they could find and all that does is make the engine bog down to where it actually hurts performance... For a small block, I would normally use the medium to heavy springs depending on the carb size... If your using the List-3310 750 cfm Holley on a "mild" 350, I'd first try the heaviest "black" spring and see how it does..... 9 times out 10, it would be a perfect spring rate for all round street cruising to where your rpm's are at below 3500 and the motor is only drawing in less than 375 cfm at the primaries.. But once you put your foot into it, you'll feel the secondaries kick in and they will open up just enough of what your motor asks of it at a higher rpm... Hope I made some sense out of this post!!

 

Any of you other Holley 4-bbl carb fans have anything to add??? I probably left something out of my last post..

 

So I removed the choke assembly today. I also changed the intake a little earlier than I planned, having dropped one of the carb stud washers down the intake (first time I've ever dropped something down the intake, I got it out). I'm letting the RTV on the intake ends cure overnight before I run it, so tomorrow I'll be good to go. Also gotta pick up another set of valve cover gaskets to double up the passenger side where the cover lip hits the new intake.