Carburetor selection for Mildly Built 302

[emorybritt 13]

Hello, 

 

I have a 1969 fastback and recently I put in a 302 bored .30 over, B cam, roller pedestal rockers, and a Holley carb with the number L6R1B (Not sure on the CFM size, assuming 600) and that is connected to a T5 Ford Racing Transmission and Ford 9" with 3.73 gears. 

 

Sorry for all the information but I am trying to narrow it down since I know all those questions will be asked anyway.

 

The current carburetor is a regular $320 one from Autozone and recently it has been studdering under mid RPM throttle hits. That is not the question that I am wondering, I am wondering what the best carburetor setup would be for this car with the given info and that it is also my daily with mostly city driving and a decent amount of short distance highway. I know this might sound redundant but I want to have the best MPG's and also the most power possible. I would rather sacrifice the MPG part of course. 

 

Thanks to everyone in advance as I am new to the forum but not new to the daily driven classic car struggle!

[MN69Grande 203]

I personally don't think there is a 'best' carb out there.  New fuel injection systems probably are the best over all solution, but they still cost at least 5 times as much as a carb when you include fuel pump, return lines, extra sensors, etc.  I think it is all in how you test and tune the carb.  For a mild 302 600 cfm is more than what is recommended but that carb has vacuum secondaries so it should work fine.  Some guys like the Edlebrock/Carter setup and I think in some ways they may be easier to tune but I wouldn't spend money to switch out what you have.  I would just suggest going through the standard tuning steps.

 

Googled Specs:

https://www.holley.com/products/fuel_systems/carburetors/classic_holley/parts/0-80457S

 

Tuning Guides:

This one has a pretty good guide in my opinion but doesn't get into CAMs, Power Valves, Secondary Springs, Squirters, etc.  But it covers the main adjustments. 

http://hotrodscott.blogspot.ca/2007/08/holley-carb-baseliningtuning.html 

 

This one has some trouble shooting techniques and gets into more of the components of the carb

http://www.bob2000.com/carb.htm

[Bob & Sue 110]

There's a lot you can do with Holley carbs to get decent gas mileage. Here's a link to Summit Auto it's a 12 part video series explains every aspect of a Holley carb from install to tuning in detail. In one of the videos it shows you where the model number is looking at the front of the choke tower there should be 2 numbers 80570 & 3250 these will identify your carbs size & series those numbers are for 570 CFM Street Avenger Polished Aluminum.

 

[1969_Mach1 334]

If your "shuddering"  description is the same as mine, before investing in another carb, check ignition parts.  Your description of the problem can also be a secondary side ignition component(s) breaking down under load.  I.E. bad spark plug, spark plug wire, coil, dist cap, or rotor.

 

For carbs, if you want simple, adjust it and drive for 10K before touching it again, go with something from Edelbrock in the 600 cfm range.  For Holley, with your setup, look at one of their Mechanical secondary carbs also in the 600 cfm range.  Carbs in the 650 cfm range will probably also work but they are slightly on the large size for that.

[MikeStang 247]

Yeah for a daily driver and close to maint free as you can get you simply almost cant beat one of the little Eldelbrock carbs with electric choke... They are great little carbs, but may give up some HP to the Manual secondary Holley.

I sure wish running a Quadrajet was practical on a Ford, I would be all over that, as these are the single most maint free carb I have ever touched and I have built a LOT of them and when done right they will perform with a Box stock Holley easily and give you much better mileage.

 

Start with tuning your carb tho.

[1969_Mach1 334]

I will add, if considering an Edelbrock carb, I recommend one of their Thunder sreies.  Those incorporate an adjustable secondary air valve giving you more control over how fast or slow the secondaries start to operate.

[machm1970 180]

I have a Summit 600 and love it, it's a Holley knock off and uses Holley parts. It's under 300 bucks and ran great right out of the box.

 

Matt

[machm1970 180]

I have a Summit 600 and love it, it's a Holley knock off and uses Holley parts. It's under 300 bucks and ran great right out of the box.

 

Matt

[1969_Mach1 334]

I haven't used a Summit carb.  But they look closer to an old Autolite copy.  Those also shared some parts with Holley.

[Bob & Sue 110]

I would in my lowly opinion say he already has one of the best carbs made after he watches the Summit Holley carb videos he'll fully understand how to tune and setup the carb for his car. He could purchase a jetting & secondary vacuum spring for under $100.00 and get excellent performance for street driving & re-tune it when he wants more power in less than 1/2 hour.

 

The one thing he didn't mention is if he has a single or dual plenum manifold, if it's a single plenum he might want to change manifolds.

 

Just my opinion everyone has their own thoughts on which is the best.

[Mike65 504]

I have a Summit 600 and love it, it's a Holley knock off and uses Holley parts. It's under 300 bucks and ran great right out of the box.

 

Matt

Is that the M2008 series carb?.

[jholmes217 65]

I think since you already have that Holley carb, you rebuild it and watch the videos another member posted.  It is a good carb, but today's ethanol fuel blend will probably require it to be rebuild at least once per year.  

 

For a daily driver, if you do replace that carb, I'd recommend the 600 cfm Summit carb another member discussed, or a 1.12 venturi Autolite 4100 carb.  These two carbs open at the top, so there are very few gasket surfaces that will leak fuel when the ethanol starts screwing up the gaskets.  Also allows jet changes by just taking the top off, so no need to drain fuel and/or remove the carb.  Just take the top off and there they are.

 

I wouldn't go with a double pumper, or a carb over 600 cfm.  

[barnett468 418]

need a photo of your carb.

 

the best type of carb for your app is one with annular boosters . all summit holley shoebox carbs have them as well as some quick fuels and some standard holleys . quick fuel and summit carbs are the best bang for the buck  600 - 650 cfm then buy the holley spring kit and respring the secondaries with a lighter spring for optimal perf.

 

edelbrock carbs are total crap and are nearly impossible for a novice to set up PROPERLY . every time i get a car with one i take it off and give it to someone i don't like and put a different type on it.

 

holley street avenger carbs are total crap.

 

you also MUST set your timing CURVE to get optimal power and mileage

[1969_Mach1 334]

I've never used an Edelbrock brand carb but have used them when they were sold under the Carter brand.  Do the Edelbrock carbs not work as good as when they were Carter brand?  The Carter brand carbs worked pretty good right out of the box.  A little power loss compared to a Holley.  But still very good for a daily driver.  Minimal tuning needed.  The idle A/F mixtures had a wide range of adjustment.  The electric chokes worked good.  The ported vacuum port was higher up in the throttle bore so there was never the issue of ported vacuum signal to the vacuum advance at idle.  All in all, reliable and consistent operation for a car that's a daily driver.

 

I agree with your opinion on Street Avenger carbs.  For me, I still don't like QFT's stuff.  That's just my opinion.

[Vicfreg 791]

Hey Emory...

 

First of all, really nice looking car.  I would like to hear more about the car.  I like the blacked out trim.  Where did you get your front bumper from...?  Also, very interested in the technique that you used for blacking out the side marker lights.   I am headed in the same direction for my 1970 Convertible Build.

 

Anyway..

 

I have a 1968 Mustang with almost the identical setup as you.   I have a roller cam 5.0 with a B303 cam and a T-5 with 3.73 gears.

 

I have a 570 Street Avenger (I know, some of you hate them), that I have had great luck with.  I use an electric choke and mechanical fuel pump.  600 CFM is plenty for your car, you do not need to go to a bigger carburetor, as your LGR1B appears to be 600 CFM. 

 

[For those Q-Jet fans, Holley made a 4165 (mechanical secondary) and 4175 (vacuum secondary) bolt on replacement for the Q-Jets].

 

An important detail you didn't discuss is what is the ignition system you are running.  

 

I upgraded to a Ford Duraspark (aka Duraspark II) on mine.  I used a 1985 Mustang GT distributor and ignition box ("blue plug") and a Painless wiring harness that has the "horseshoe" style coil connector, and the Duraspark plug interface.  I use a MSD Blaster 2 coil that hast the horseshoe terminals.   I replaced the resistor wire ("pink wire") with a ballast resistor.  My vacuum advance port is plugged on the distributor. 

 

The 1995 ignition set up was recommended by the Ford Racing Tech Line.  (1985 is the only Mustang that used a 5.0 and a carburetor, and has a really great factory advance curve).    You can get the distributor and ignition box at Autozone or Advance Auto Parts.  

 

Do not use the later EEC based Duraspark  (brown plug, etc) ignition systems with your carburetor. Also, if you are not running a roller cam engine, you need to change out your distributor gear.  Lots of articles on the Web about this.

 

I have no flat spots, hesitation, or bogging down problems with this set up.  The car warms up quickly and runs great.  I am not concerned with gas mileage or my carbon footprint.....

 

Hope this helps.  Good luck!

[1969_Mach1 334]

On a side note, Ford Racing use to sell an "Extra Performance Ignition System".  It was a Duraspark II ignition module and coil made by MSD, and an OEM type wiring harness.  The ignition module had a rev limiter built in.  It worked with a Duraspark or any other magnetic trigger distributor.  I had one for a while, sold it and wish I never had.  Nice setup, simple two wire connection, ground and switched 12V.

[Fordzilla06 11]

emorrybrit your blacked out '69 looks amazing.  Did you paint the bumpers or are they fiberglass?

 

Also I am currently looking into the Fitech fuel injection system.  It's about a grand but everything I have heard and read about it points to worth every penny.  Just another direction you might think about going.

[1969Fstback 58]

emorrybrit your blacked out '69 looks amazing.  Did you paint the bumpers or are they fiberglass?

 

Also I am currently looking into the Fitech fuel injection system.  It's about a grand but everything I have heard and read about it points to worth every penny.  Just another direction you might think about going.

 

Same here on Fitech.  I ordered part of the parts already.  I have a 570 Street Avenger and have not been overly pleased with it.  My plan is to put the Fitech on sometime in April.

[Max Power 74]

For those that are saying the Street Avengers are crap, I would be interested in hearing why you think so?

[1969Fstback 58]

My "not overly pleased" is more of a carb statement in general.  Cold starts, tuning at idle versus on throttle and so on.  

[uncledoodoo 31]

I've bought 2 of the Holley refurb 650s with electric choke directly from Holley on ebay for less than $300 each, I have one on a 335/hp mildly built 289 the other on my stock 69 351W.  Both sitting on Weiand Stealth intakes. So far I love them.

[Bob & Sue 110]

I have nothing to gain or lose I just know Holley carbs inside and out all carbs are about the same. The one thing about using Holley is it gives you a wide range of tuning options I hadn't tuned a Holley in 30 years till purchasing this car with the Street Avenger on it after some research it all came back. In the late 60"s I had a 64 Plymouth 426 Hemi Ramcharger running in SS/BA . If anyone is interested here is an article on the reason racing teams went from Carters to Holley's. I would prefer just running Hilborn Injection if anyone has a setup for a 351 I'm interested.

 

Link to this article and history of Ford Mopar Nascar & Drag Racing wars.

 

http://www.allpar.com/racing/ramchargers/ramchargers-11-drag-racing-hemi.html 

 

How to get the Hemi cars going was the number-one job upon returning to Detroit. Ramcharger Gary Congdon, the on-site Holley carburetor representative, suggested trying Holley carburetors, adding that the Carters were turned the wrong way. With the cobbled-up linkage, the carbs were mounted with the primary bores outboard. After sorting out the fuel distribution and jetting, the Holleys produced about 10 more horsepower.

On the first warm day, in March, we began testing anew. Wow, the car went three to four mph faster with the Holleys than with the Carters. We never looked back, it was Holleys from then until the fuelinjection. There was a significant lesson to be learned, but we were not paying attention. Running steady state on the dynomometer does not represent the transient nature of drag racing. However, at that time there was no alternative to cooking the engine on the dyno under steady-state conditions.

Detroit Dragway staged the Division III Grand Opener on April 26. There was a host of new factory sponsored A/FX Thunderbolts and Comets presenting an ideal opportunity for the public debut of the Hemi. So we had two cars, the A/FX and the Super Stock, and only one driver, as Herman Mozor had announced retirement to enjoy another life. Roger Lindemood of Color Me Gone fame was drafted to drive the A/FX car. Bottom line: we mowed them down. Both cars set class records: Thornton won StockEliminator, and Lindemood won Street Eliminator.

[emorybritt 13]

Here I am, 5 years later googling a about my carb again and look, a post with my details with amazing suggestions! Funny how forums are still the goat for this stuff.

[69RavenConv 302]

Don't be such a stranger :)

[RPM 1,243]

Well... did ya get the carb tuned?

Your pic in the first post here, is that in Mobile Alabama?