Carb for 302

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Author Topic: Carb for 302  (Read 10643 times)

Offline FickleLife

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Carb for 302
« on: August 07, 2022, 12:59:13 pm »
I’m looking for a new carb for a mild 302. Looking for best street options.

I was thinking either Holley Street Avenger 570 or the Summit 600 carb. I’m leaning towards the summit as it has annular boosters, has additional hardware such as fuel rail and heat spacer, and is about 700aud landed vs 900+ for the street avenger (plus another hundred or so for that missing hardware)

Just wondering if there are any other options or thoughts from the brains trust before I make a call?



Offline GEOFF289

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Re: Carb for 302
« Reply #1 on: August 07, 2022, 06:03:25 pm »
Both are technically too big for a mild 302.

https://performanceimprovements.com/blogs/news/carb-size-matters-what-size-carburetor-do-i-need

The numbers in the formula the link provides come out to about 408 cfm. That said, there are probably more 600 cfm carbs on these engines than anything else, like mine. I had to go down a few jet sizes from what the carb came with to get it within the bounds of a reasonable afr but its still richer than is ideal.

Offline Micks66coupe

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Re: Carb for 302
« Reply #2 on: August 08, 2022, 02:08:02 am »
Both are technically too big for a mild 302.

https://performanceimprovements.com/blogs/news/carb-size-matters-what-size-carburetor-do-i-need

The numbers in the formula the link provides come out to about 408 cfm. That said, there are probably more 600 cfm carbs on these engines than anything else, like mine. I had to go down a few jet sizes from what the carb came with to get it within the bounds of a reasonable afr but its still richer than is ideal.

I agree with Geoff on this, going to big with carb selection is a common problem and assuming bigger is better is the wrong way to go. I run an Edelbrock AVS2 500 CFM on my 289 which also has Edelbrock Performer manifold, electronic ignition and tuned length extractors. Follow Geoff's link and do more research before you order anything, and for the record over the years I've run Holley's, Edelbrocks, Carters and even an Autolite 4100 carb (still got that one tucked away)

Offline FickleLife

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Re: Carb for 302
« Reply #3 on: August 08, 2022, 06:31:19 am »
Thanks Geoff and Mick

I’ve added the AVS2 Carburetor #1901 500 CFM With Electric Choke to the list and is the front runner.

Looking at the options for 500cfm it doesn’t look like there’s much out there with 4 barrels other than the Edelbrock https://www.summitracing.com/search/part-type/carburetors?N=cfm-range%3A500-599-cfm%2Bnumber-of-barrels%3A4

Is there any other brands I should consider?
« Last Edit: August 08, 2022, 06:43:58 am by FickleLife »

Offline pmb0186

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Re: Carb for 302
« Reply #4 on: August 08, 2022, 09:54:53 am »
I run a stock 289 with a autolite 4100 1.08 and it’s fine and probably ok for a mild 302
If I didn’t have that I would go Holley 570 vac secondary or the summit as you suggested
A larger carb will not effect performance but drive ability and fuel economy within reason.
I would keep away from anything double pumper.
As for tuning out of the box 9 time out of 10 will be ok.
Unless it drives like a pig do a colour check on plug and drive it
does anyone remember laughter

Offline FickleLife

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Re: Carb for 302
« Reply #5 on: August 08, 2022, 03:39:40 pm »
Thanks pmb0186

I'm still leaning towards the Edelbrock 1901 for the annular boosters over the street avenger / summit. At 500cfm, it's plenty large enough and with those annular boosters it should have better low-mid rpm perf where it will be 95% of the time.

the summit has annular boosters (for street avenger it's a relatively expensive upgrade), and pricing wise is slightly less than the Edelbrock, but also probably has limited support here in Aus even though it takes holley parts.

 

Offline GEOFF289

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Re: Carb for 302
« Reply #6 on: August 08, 2022, 05:08:16 pm »
There's reason Ford put those 4100's on these engines originally.

Offline FickleLife

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Re: Carb for 302
« Reply #7 on: August 08, 2022, 07:35:11 pm »
There's reason Ford put those 4100's on these engines originally.

Aren’t the 4100s 600cfm?

Offline GEOFF289

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Re: Carb for 302
« Reply #8 on: August 08, 2022, 08:43:10 pm »
Aren’t the 4100s 600cfm?

With the 1.08 venturi they were 480 cfm. 1.12 was 600.

Offline FickleLife

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Re: Carb for 302
« Reply #9 on: August 20, 2022, 08:13:59 pm »
The Edelbrock avs2 500cfm is arriving on Tuesday, so my attention is turning to fuel lines. I bought the Edelbrock fuel rail and filter 8131 but have conflicting info on the fuel pressure regulator

Some people say you must have one. Others mention that the factory mustang fuel pump can/does only do 6psi which is fine for the edelbrock. Am I ok with the factory mechanical fuel pump or should I put a regulator in line? Would rather not have something extra to bolt to the side of the engine bay…

Offline GEOFF289

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Re: Carb for 302
« Reply #10 on: August 20, 2022, 08:24:03 pm »
Don't think you need a fuel pressure regulator.

Offline FickleLife

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Re: Carb for 302
« Reply #11 on: September 05, 2022, 01:35:55 pm »
Just installing the avs2 now. I’ve built a bracket to support the accelerator cable and the linkages look good. Pics are at

https://imgur.com/a/SZwaSWh

The issue I’ve got is there’s nowhere suitable to attach the return spring. The kit that is needed to add the ford kickdown https://www.edelbrock.com/ford-throttle-lever-adapter-in-gold-finish-for-1968-and-later-1483.html takes up the hole where you’d attach a spring to go towards the back of the engine (circled in green on the last pic), and the flimsy bar it comes with I wouldn’t trust even though it’s just to return the kickdown.

I bought an aftermarket spring bracket but it’s too short- the spring would bind when at wide open throttle. Any suggestions on a kit or a bracket I can make to attempt to make it neat and more importantly sturdy?

Option1-  I keep the kickdown return spring that came with the kit, move that aftermarket bracket to the rear and have a spring go from that to the “bolt” on the bottom of the arm, with some way for the spring to pivot and not be fixed to the bolt.

Option2 - get (or make) something like https://outlawspeed.com.au/shop/carburetors-accessories/mo64928 and place it at the front and have both the kickdown and main accelerator spring hang off it

« Last Edit: September 05, 2022, 01:58:05 pm by FickleLife »

Offline jiffy

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Re: Carb for 302
« Reply #12 on: September 06, 2022, 10:54:39 am »
I wouldn't use the spring return bracket that came with the kit - the natural action on the carb nut is to undo it, which (if that happened) would loosen the nut, the bracket would swing in and remove return pressure on the throttle and you might be stuck with the throttle open - don't do that.

I would (if the nice short aftermarket alloy bracket is too short) either find a spring with a longer unwound portion like these:


Or - as that bracket has holes in it - I would plan on lengthening it with a bolt-on piece that allows you to raise the spring attach height to where you're comfortable.
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Offline FickleLife

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Re: Carb for 302
« Reply #13 on: September 06, 2022, 06:17:53 pm »

Thanks jiffy. I’ll see if I can find a spring like that. I found a good place to mount the bracket and am using a spring ( that’s too loose - will get a better one) from Bunnings, seems to work ok.

The latest photos are at the bottom of the album https://imgur.com/a/SZwaSWh

Offline GEOFF289

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Re: Carb for 302
« Reply #14 on: September 06, 2022, 06:48:52 pm »
You need some nice shiny rocker covers now you've got shiny induction.

Offline FickleLife

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Re: Carb for 302
« Reply #15 on: September 06, 2022, 08:03:54 pm »
Don’t worry, they’re next :) looking for a good cheap second hand pair of finned alu ones