383 CARB recommendations.

[72golddustermike]

70 roadrunner
383 .030 over 9.5 compression
906 heads
Hooker comp headers
Comp xe268 cam
Tci breakaway converter
3.91 gear with 265/60 15

Holley tech suggests 650 double ?

 

[91r/t]

I have a pretty healthy 383 and I run a 750 vacuum secondary on it. It loves it and handles the fuel fine. I am sure you could get away with the 650 no problem and cruise fine......but you may be giving up some mid range and high end torque with the smaller carb. A 750 can be tuned a bit to run on that engine just fine. Either way you'll be fine driving, just preference in having the little extra power or not. I have mine tuned with perfect plug color and got 12.5 MPG on the way home from Carlisle. From what I remember, it came pretty close out of the box jet wise. Just had to add some fuel with the accelerator pump squirter and cam. I'd go 750 vacuum secondary, especially with the automatic trans. I think mine is a 4160 Holley, but its been 7-8 years since I added and tuned it to the engine.

 

[Frank Mopar]

Id go with whatever Holley said.

 

[91r/t]

I have always been under the impression that the double pumpers with mechanical secondaries are best for stick cars, and vacuum secondaries are more suited for the autos. Holley suggested a 650 double pumper for an auto car which already tells me what I have heard about the recent Holley tech support has gone by the wayside. There's a few guys still there that are knowledgeable, but I have heard their tech service has gone downhill for some stuff.

 

[68Moparmaniac]

91r/t's opinion is spot on. I'm of the mind that I would rather have it and not need it than need it and not have it, 100 cfm is still a 100 cfm

 

[Frank Mopar]

Too big is just as bad as too small.

There are many carb cfm calculators online to find out what you need.

 

[matthon]

I'm no expert on carbs, but my built 383 4 speed ran extremely well with a 750 dp, great throttle response, in fact it might have been an 850.
I put a 600 vaccum secondary on it just for the heck of it and it idled great but would barely move.

I went to efi and don't miss the carb.

 

[91r/t]

Too big is just as bad as too small.

There are many carb cfm calculators online to find out what you need.

Agree with you there.....too much carb can make it run like crap for sure. The 750 just seems like it is well suited for a mild to decent 383 from my experience. My fathers almost stock 383 in his charger has a 600cfm single feed on it and it seems lathargic at times like it wants more for sure. The recommendation of a mechanical secondary carb on an automatic makes me question whoever he was talking to at Holley.

 

[Jcharger]

Normally, I would say the 650 DP, but given the gears, I wonder about the 750. The catch with a carb that is too large is you can't really tell unless you swap in a smaller one and do back to back testing. They both need to be dialed in and there is a noticeable difference stepping into the throttle if the carb is too big. Booster type can also make a difference, but can cost.

 

[Frank Mopar]

Give AED carb a call. Thats all those guys do and are very helpful.

 

[Bill Monk]

I would recommend a Holley street avenger. I have run this carb and really liked it. It is easy to tune and it's a 670 cfm carb. It also has vacuum secondaries which in my opinion is better for the street than the DP. The electric choke is a good thing too.
https://www.summitracing.com/parts/...MIybmWy8GR4gIVxrbACh3kOgcBEAQYAiABEgJwAvD_BwE

 

[fratzog lover]

I would recommend a Holley street avenger. I have run this carb and really liked it. It is easy to tune and it's a 670 cfm carb. It also has vacuum secondaries which in my opinion is better for the street than the DP. The electric choke is a good thing too.
https://www.summitracing.com/parts/...MIybmWy8GR4gIVxrbACh3kOgcBEAQYAiABEgJwAvD_BwE

What was your engine build? What jets did you use?

 

[Bill Monk]

What was your engine build? What jets did you use?

340 with stock J heads, comp cams 268 cam with roller rockers and small headers with a 4 speed. I'm not sure what jets were in it out of the box but I ran it like it came with no issues. I run a six bbl in the roadrunner, the street avenger was on a 68 barracuda

 

[fratzog lover]

I have a j head 360 with a comp xe268 and comp roller rockers. And a 670 on the shelf. I guess its time to try it.

 

[Bill Monk]

I have a j head 360 with a comp xe268 and comp roller rockers. And a 670 on the shelf. I guess its time to try it.

Pretty close to the same setup I had and it worked for me. Good luck bro!

 

[Lazerwolf]

I would run a 750 on that. I have a similar 400. Both Edelbrock and Holley recommended in the 600-625 range. Had a 600 Edelbrock on there and could never get rid of acceleration bog. Had Holley 750 vacuum secondaries on shelf in garage. Threw that on there and runs great. I don't think it was a Edelbrock/Holley thing, just a little bigger CFM needed in my configuration. Each engine is different but that is what worked for me.

 

[RJRENTON]

Gentlemen,
My opinion....
How about a Carter AVS (NOT the Edlebrock AVS not a true copy of the original AVS design) for 1970 375 HP 440. OR a Carter # 3705sa, as used on the Stage 3 MaxWedge (750 -780 CFM). This is the one with 1-11/16" primary AND secondary throttle bores and the adjustable secondary air valve. The original AVS design would need to be slightly mofified to eliminate the off idle air bleed circuit (which was created for emission requirements and caused lean an off idle stumble) and POSSIBLY increasing (by 0.001" - 0.002") the idle feed restrictions, located in the primary booster venturii.
It seems as if everyone wants to use either HOLLEY or EDLEBROCK.....not sure why? The 440 / 375 hp engine's OEM Carter will flow approximately 750 - 800 CFM @ 1.5" pressure drop AND have the adjustablity of the secondary's air valve.
It seems as if everyone likes to run too much carb without any consideration for mixture velocity (from idle thru wide open throttle response)....the faster the velocity the better.
Everyone knows that the next door's neighbor's brother-in law's cousin's best buddy is the definitive source for carburetor (as well as just about everything else) unsubstantiated information, sort of......but this is just my opinion.
Bob Renton

 

[747mopar]

Give AED carb a call. Thats all those guys do and are very helpful.

Best carb I ever bought was going through someone who knew how to spec one out to the T, unfortunately Holleys takeover of QF carbs brang that to a halt. If you can find someone like that you can't go wrong. I however would not trust Holley, the reason the guy I used quit offering his service was because of Holley and they're lack of on hand EXPERIENCED techs.

Me personally, I'd run a 750. I bought an 870 Avenger vacuum sec then an 850 Demon DP off of Ebay so I could run them back to back, I liked the DP but idle quality was a struggle... ordered a brand new 750 Quickfuel DP then sold the other 2. In my case I'm running a standard with 3:55's behind a 456" stroker that sees 6,000 rpm often. There's more to vacuum sec vs double pumpers than what you hear but in general heavy cars with automatics and street gears won't benefit from a DP.

 

[91r/t]

Gentlemen,
My opinion....
How about a Carter AVS (NOT the Edlebrock AVS not a true copy of the original AVS design) for 1970 375 HP 440. OR a Carter # 3705sa, as used on the Stage 3 MaxWedge (750 -780 CFM). This is the one with 1-11/16" primary AND secondary throttle bores and the adjustable secondary air valve. The original AVS design would need to be slightly mofified to eliminate the off idle air bleed circuit (which was created for emission requirements and caused lean an off idle stumble) and POSSIBLY increasing (by 0.001" - 0.002") the idle feed restrictions, located in the primary booster venturii.
It seems as if everyone wants to use either HOLLEY or EDLEBROCK.....not sure why? The 440 / 375 hp engine's OEM Carter will flow approximately 750 - 800 CFM @ 1.5" pressure drop AND have the adjustablity of the secondary's air valve.
It seems as if everyone likes to run too much carb without any consideration for mixture velocity (from idle thru wide open throttle response)....the faster the velocity the better.
Everyone knows that the next door's neighbor's brother-in law's cousin's best buddy is the definitive source for carburetor (as well as just about everything else) unsubstantiated information, sort of......but this is just my opinion.
Bob Renton

Biggest for me is that those carbs are few and far between now man. We are talking about a 50 plus year old piece thats hard to come by. Can't exactly find those on the shelf anymore. I'm also just familar with Holley's and for being 32 years old not many are even into carbs anymore. Everything is going EFI, so I use what I am familiar with and I know works for me that I can tune well. As soon as you say Max Wedge, you might as well yank your drawers down price wise, as that **** is through the roof now adays.

 

[RJRENTON]

Biggest for me is that those carbs are few and far between now man. We are talking about a 50 plus year old piece thats hard to come by. Can't exactly find those on the shelf anymore. I'm also just familar with Holley's and for being 32 years old not many are even into carbs anymore. Everything is going EFI, so I use what I am familiar with and I know works for me that I can tune well. As soon as you say Max Wedge, you might as well yank your drawers down price wise, as that **** is through the roof now adays.

The simple thuth is: "You pay your money and tske your choice". Vintage carbs are like fine wine.....they get more expensive with time....but like fine wine perform remarkably well. There was an old addage: "fancy gizmo's don't work" (aftermarket fuel injection) or work after spending tons of money and time and frustration to make them do what's advertised.
I am a classic car person who strives to make my efforts appear original....using OEM parts when possible. The old vintage Carter carbs are available on the internet or eBay. Sometimes at reasonable prices.....most vendors know what they are offering....some carb "experts" have no clue as to their correctness.....or search for carbs offered as cores....these are excellent sources of the small parts removed by these self proclaimed experts.
It is truely amazing how many persons have no clue how a carb functions yet trust strangers and their often misguided reasons or opinions and will spend $$$$, based on what they hope to achieve. DO YOUR OWN DUE DILIGENCE .... do not just go by hearsay. Again, this is just my opinion.
Bob Renton