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Best carb for my eb 302

SSDDBRONCO

Bronco Guru
Joined
Nov 12, 2009
Messages
2,170
Loc.
Los Angeles
Hey wats up everyone. I recently bought a 73 bronco and i am planning on buying a new carb. Im interested in the Holley Truck Avenger, but the thing im having a hard time is which one i should get the 470 cfm or the 670 cfm. My 302 is stock with Heddman headers, and a performer intake. Please your help is greatly appreciated.

Thanks
 

broncnaz

Bronco Guru
Joined
May 22, 2003
Messages
24,341
The 470 is fine really no more than a 600 cfm carb is fine for a stock 302. What carb do you have now?
 

blubuckaroo

Grease Monkey
Joined
Jun 11, 2007
Messages
11,795
Loc.
Ridgefield WA
I have a little 500 CFM Edelbrock that I've really enjoyed. Just a bit of tuning with the metering rods and springs is all it takes to make these work well. If I do this again I may go to a Quadrajet. The advantages are a small single float bowl that reduces slosh on steep angles, and those teenie-weenie primary venturis that have more velocity. The only down side is that the Quad is taller because of the spread bore adapter plate needed.
 

4G5

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Oct 7, 2009
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Newport News,VA
Whatever you do, stay under 600 cfm. I have had a lot of Edelbrocks over the years and they have never treated me wrong on the street. I have never ran the Holley TA but have heard mixed results out of them. I recently purchased a Holley 1850. Excellent carb. Remember that if you are mainly running on the street that Edelbrock is prob. your best bet. If you are doing minor offroading then I would say a basic Holley 600. Like I said before, if you are into some serious terrain maybe the TA would be best (that's what their designed for) but I have no experience with them and their expensive.
 

phred

Contributor
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Aug 25, 2006
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Earth
I like the edelbrock as well. I run it on my tow rig. I had a jet performance q-jet built for my eb. Love it. cost a bit over 400 bones but as built to match the specs on my engine. BCB sells them.
For the money on a stock engine I'd go with the edelbrock.
 

Z Bronco

Bronco Guru
Joined
Mar 17, 2007
Messages
1,138
My 670TA is great off road, but still have not been able to get it dialed in for street. It bogs, sputters under load at higher RPMs, and the plugs when pulled look good. Still a work in progress. If your Bronco is mainly a street rig the Edelbrock would be a better choice. I miss my old Carter AFB on the street, but the Holley is way better off road.
 

carmi

Full Member
Joined
Aug 22, 2007
Messages
178
Loc.
Oroville
I would say go with the smaller 470cfm. You will get better offroad performance as the air velocity will be higher at lower rpm, giving you a better low end - mid end. Unless you plan on consistently running higher rpm (over 3000), the 470 will run much more efficient.
 

broncaholic

Full Member
Joined
Aug 17, 2009
Messages
280
I have a little 500 CFM Edelbrock that I've really enjoyed. Just a bit of tuning with the metering rods and springs is all it takes to make these work well. If I do this again I may go to a Quadrajet. The advantages are a small single float bowl that reduces slosh on steep angles, and those teenie-weenie primary venturis that have more velocity. The only down side is that the Quad is taller because of the spread bore adapter plate needed.

Ditto. Ran an Edelbrock 500 CFM with a Edelbrock Performer intake for years. Also purchased the metering rod kit for higher altitudes and installed the Off-road float kit as well. Was real happy with the performance although I couldn't keep my foot out of it and averaged 13 mpg. I was also running an Edelbrock cam and pertronix ignition.
 

1970mule

Bronco Guru
Joined
Dec 20, 2007
Messages
1,515
I have had both ethe 470TA and the 670TA, i can say that i did not notice much difference in the preformance. I have a mild 302 pretty much stock with headmans and a edelbrock intake manifold. when i had the 470 on i just could not get it dialed in, and it sputter on the take off and was ok when gasing it, just the stop and go sucked, it also was an earlier one so it was made crappy, when i called holley they said "OH, its to small for a 302 you need the 670" i said to them everything i ever heard says you should stay under 600cfm for a stock 302, anyway they let me swap it out for free even tho i lost my receipt. when i got the 670 i was able to tune it ok, but still had the same exact problems of the 470, i think it is just the mannerisms of that carb line you just can't tune them for street, i have not yet heard anyone that can, but off road its great, i took it up some pretty steep inclines no sputter and coming down no sputter in the lower gear high rpm range it works flawlessly. the pro about the 670 if you decide to beef up your 302 you are set on a carb.
 

73stallion

Bronco Guru
Joined
Mar 5, 2004
Messages
16,786
Loc.
Eugene, OR
another vote for the 470TA. i've had mine for a few years now and it does great on and off road. it had some good testing off road a few weeks ago and it didn't disappoint me at all. only konked out once doing a climb when i hit a big rut and the front end caught some air.
 

22213evl

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Mar 14, 2007
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Rio Rancho N.M.
the 470ta will work for a 302 as long as your at or around sea level, once you get some altitude in there the lack of oxy makes going to the 670 a must. great carbs the 670 works great for me.
 

br0nc0xrapt0r

Loves pickles
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Sep 28, 2007
Messages
5,437
engine displacement x max rpm divided by 3,456 = ideal cfm

so for a mild 302 with a few bolt on acc you would want an edelbrock 500cfm for tinker free no problem operation

if you want to play with it a bit more and get it tuned just right then the holley truck avenger 470 is what you want.

I am currently running an edelbrock 500 on my 302 and it works awesome, but I am switching to a holley TA 470 to get the optimum setup.

overcarbing a motor is one of the biggest problems that occur just to make my point I have a 78 bronco that had an edelbrock 750 on it and i ran like crap, I then took the 500 off the 302 and put it on the 78's 351 and it ran like a top.
 

broncaholic

Full Member
Joined
Aug 17, 2009
Messages
280
You'll have to explain the elevation thing to me.

As you get higher in altitude, the air thins. This causes a carburated vehicle to run alot richer with fuel. You need to compensate this by changing out jets and or metering rods on most carburators.
 

blubuckaroo

Grease Monkey
Joined
Jun 11, 2007
Messages
11,795
Loc.
Ridgefield WA
As you get higher in altitude, the air thins. This causes a carburated vehicle to run alot richer with fuel. You need to compensate this by changing out jets and or metering rods on most carburators.

So if I get a 670 I won't need to make adjustments like jets and metering rods for higher altitude? Please explain. You could save a lot of folks a lot of problems.
 

TeriAnn

New Member
Joined
Nov 20, 2009
Messages
11
So if I get a 670 I won't need to make adjustments like jets and metering rods for higher altitude? Please explain. You could save a lot of folks a lot of problems.

Sorry it is not so easy.

The volume of air you suck through a venturi is dependent upon the swept volume of your engine cylinders, the engine RPM and the density of the air being sucked into the carb (Its actually little more complicated but this is close enough for discussion). The density is mostly dependent upon the air temperature and altitude (The higher you are the less air pressure you have)

Your main & idle jets are chosen to provide the right amount of fuel to your cylinders at given average air pressure. usually somewhere around 12:1 (max power) through 13.5:1 (economy). The carb is designed to adjust for small differences in pressure but bit can't self adjust a whole lot.

When you change altitude from where you set the carb up the air density changes and the air to fuel ratio produced by your carb changes. A carb set up for high altitude driving will run too lean at low altitudes and one set up for sea level will be running increasingly rich as you climb.

All this is independent of the flow capacity of the carb. It is all to do with the air to fuel ratio you set up when you jetted the carb. The carb can compensate a little, you set the air to fuel ratio up a little rich of lean best air to fuel mixture on the grounds that it is best to run a tad rich than too lean.

Bottom line is that carbs just can not self adjust for more than a small altitude change and at about 4000 feet of altitude change your engine will be running crappy enough that rejetting is a good idea.

This is where EFI is so superior. It self adjusts for changes in fuel density (changes in altitude and changes in air temperature going into the engine).

So bottom line is if you drive regularly in places that are more than 4000 or so feet altitude difference you need to set the carb up for low altitude driving then again for high altitude driving. You just carry the jets & tools along to allow you to swap out the jets when the altitude change is enough. This is independent of the CFM capacity of the carb.
 

br0nc0xrapt0r

Loves pickles
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Sep 28, 2007
Messages
5,437
what he is saying is the the higher the cfm the more fuel to air ratio the carb will put out/ capable of supporting. so what you need to do is get the correct cfm carb for your motor and then tune it to your elevation.
 

John Marinan

Contributor
Sr. Member
Joined
Aug 9, 2009
Messages
680
Loc.
Durango CO.
On the same subject, I'm looking at installing a set of GT 40s on my stock Bronco, because I have them. I live at 9,000 ft. and use a tuned 500 edelbrock. Would this be a waste of good heads? I was thinking more airflow couldn't hurt.

thamks
 
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SSDDBRONCO

SSDDBRONCO

Bronco Guru
Joined
Nov 12, 2009
Messages
2,170
Loc.
Los Angeles
thank you all for your help i really appreiciate it if you want to tell me your idea feel free to im always open to new ideas and options
Thanks
SSDDBRONCO
 
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