[RocktimusPryme]

I tried Google for this but didnt come up with much info.

Im putting together an engine on the cheap for summer street strip action. Trying to source a lot of parts used to keep costs down. I live in late model circle track country. So there are alot of roundy round carbs for sale at pretty decent prices. Many of these are built by reputable builders that are pretty trick. People sell them because they are switching to alcohol, changing classes etc.


Quesiton is, how different is a carb built for a circle track different than a normal Holley HP type street strip setup? Are there dramatic differences, or is it just like any basic carb tuning? Jet up or down to get in the good AFR range?


Secondary question, Im using a flat tappet with a lot of duration. Ive read some info that says when using a cam with a lot of duration annular boosters can be an advantage to keep the carb manners decent on the street side of a street/strip application. Im considering doing drag week, so it would need to be tolerable on the street. Any truth to that large duration liking annular boosters? Alot of said circle track carbs Im looking at have annulars.

I would also like to do some pass by pass testing on the firebird with a good holley vs the Qjet.

[shaker455]

You'll have to take it apart and measure all the restrictions up to size up it's intended use to modify for street action.
The annular booster is larger can be efficient more so than the downleg or straight leg most times requiring less main jet.
Street manners depend a lot on idle, transition, and correct bypass air circuits which you have to tune to your own combo.

[RocktimusPryme]

Originally Posted by shaker455

You'll have to take it apart and measure all the restrictions up to size up it's intended use to modify for street action.
The annular booster is larger can be efficient more so than the downleg or straight leg most times requiring less main jet.
Street manners depend a lot on idle, transition, and correct bypass air circuits which you have to tune to your own combo.

Yeah, I guess to tighten up my question, when you buy a carb from Holley. Say a classic 850 double pumper, it will require some tuning. But probably not more than the standards jets/powervalve type stuff.

Your saying a circle track carb is likely to have been much more heavily modified from off the shelf Holley form and would require more drastic changes to make it a drag racing, street strip carb? Like it might need different metering blocks and all?

[shaker455]

If it's built with an intended use of one type it's calibration will be focused on the area of most use like WOT.
So you'll find out once you dig in as most likely mods will not be documented.

[RocktimusPryme]

Lets say it is calibrated for heavy throttle. That would make it just fine for straight line track use, but not so much on the street? Does the annular booster make it a bit more forgiving at lower RPMs than a similar set-up with downlegs?

And FWIW, I dont mind a basic rebuild, but if Im likely to have to throw a bunch of money at it to un-dirt track it for lack of a better term, it sorta defeats the purpose. Ill probably just pass on them as a whole. I know you are always gambling with used parts as a whole, but if these dedicated carbs are at least more than likely not going to be good for my purposes as is. Ill either wait till swap meet season and buy a basic HP to rebuild, or bite the bullet and buy a new one.

[shaker455]

I don't know your combo but you can buy a decent off the shelf Holley with a predictable fuel curve for about $550.

[RocktimusPryme]

Originally Posted by shaker455

I don't know your combo but you can buy a decent off the shelf Holley with a predictable fuel curve for about $550.

I agree. I do like the allure, of buying a swap meet HP for $150 and throwing a kit at it. That said there is also the allure of the easy button. While I want to use it for testing with the Firebird its primary purpose is for a gasser project im building. So I feel like Im limited to "classic" holley selections. I think a newer style aluminum carb on it will stick out like a sore thumb.

Setup is classic lipstick on a pig. .040 454 off craigslist with a summit K1303 hyd flat tappet......that Im throwing Brodix Dragonslayers 320s at lol. Like I said, its just a fun little project. I overdid it with the heads assuming Ill buy a better shortblock in the future. 540 or something.

With the exception of the firebird having a much better roller cam, the motors will be close. The BBC will have a better head, and CI will be similar. So if its good for the BBC it should be pretty good for testing on the Pontiac too.

[shaker455]

they have quite the selection... you want a standard green carb?
Whats the engine size & combo?

[RocktimusPryme]

Originally Posted by shaker455

they have quite the selection... you want a standard green carb?
Whats the engine size & combo?

I edited it up into the previous post. And yeah, classic green or gold dichromate. Whatever they call it. Supposedly those new Chinese parts, assembled in America Brawlers are pretty damned good for the money, but again I just think it would look out of place on a straight axle car.

[shaker455]

Got it,
Which head flow.. 370 cfm?
From info you posted so far and that cam finishing up about 6500 rpm which sounds a of an rpm stretch for the duration I would figure an 850 is what your shopping for.
Annular will reduce your total cfm but will work nice on street once dialed in.

[RocktimusPryme]

Originally Posted by shaker455

Got it,
Which head flow.. 370 cfm?

Its the smaller Dragonslayer, they claim 370 @ .800. But I m not running near that lift. I think this motor would run out of PV clearance at .600. So Im running a .540 lift cam with a lot of duration. Obviously swapping out the supplied brodix springs for something more tame.

The whole head is a neat program. In theory its an as cast replica of their fully CNC ported Race Rite head. Relatively new on the market.

[shaker455]

Should be fun
If you don't mind color here are a few budget minded units:

https://www.holley.com/products/fuel...arts/0-67201BK
https://www.holley.com/products/fuel...parts/BR-67332

Do you want a choke tower unit?

[RocktimusPryme]

I don’t think I want a choke tower. It’s a summer car.

That’s kind of another carb specific rabbit hole question. Since the dawn of time people have been milling those down. But don’t HP units have different metering blocks? So if you have a choke tower carb and mill it off but don’t do anything else. Did you do yourself any good?

Isn’t that track warrior a circle track carb?

I’m also a fan of Holleys refurbished stuff. I bought one before and was happy. The availability comes and goes. They do usually have one of those “NASCAR spec” 830s. Would that be a good choice? I would think it’s similar to the track warrior.

I do think I want to try the annular boosters if I can.

[shaker455]

Annular is fine and if you look at spec page the Track warrior carb has more strip orentainted main jets.
Both with 4.5 PV so that a good place to start
830 is bad choice for many reasons: blocks,base plate too small, bypass air holes in throttle plate way too big so the main jetting has to follow suite.

[455rebel]

I actually just last week did this. A friend passed that ran dirt for years, his family gave me a 4150, K-B Holley, that came off his car when he upgraded.
4 corner idle,PV in both ends, adjustable secondary idle screw from top, changeable air bleeds, machined jet blocks with changeable pvcr. It had 83 main in both ends, I put 80 in front, cleaned all the red clay dust out and bolted it on a 407 AMC, 400hp engine.
Runs and idles in gear better than any carb I ever owned.
If their cheap, buy one, this one was over 800$ new, I got 50$ in parts invested?

[RocktimusPryme]

Yeah I’ve seen that tag before. Along with Stealth, Braswell, and others. I don’t see any for free, but I see plenty that look like that for 3-400 used for one season.

That said, I guess you don’t really know how the carb is setup until you open her up.

I actually just found a carb builder on eBay that had a street strip custom AN 950. It’s aluminum, but I sent a message asking how much a similar setup would be in green. It was reasonable, like 550 bucks.

I know some of you guys do carb work too, feel free to PM me an offer.

[1968GTO421]

I know of some carb rebuilders who use this to get that "new" carb look. Eastwood has a good rep so it may do the job turning a newer aluminum carb into an older looking one.

https://www.eastwood.com/carb-renew-...5-oz-5361.html

[shaker455]

That's a good idea to give it that old look but is lacquer based so gas will take it off easy.
Maybe some ceramic engine type paint....
I did some coatings this past summer on a nasty corroded holley