4 barrel upgrade

[naa10104]

Hello,

I have a 73 convertible with a 351 c 2 barrel carb, dual exhaust c6 auto. Would like to install a 4 barrel intake and carb to improve performance. Have heard this is a very good upgrade. Question, how big a difference is there between a modern aluminum intake and modern carb as opposed to keeping the vehicle historically correct with a period correct cast iron intake and carb ? Thanks for your replies.

 

[TommyK]

Hello,

I have a 73 convertible with a 351 c 2 barrel carb, dual exhaust c6 auto. Would like to install a 4 barrel intake and carb to improve performance. Have heard this is a very good upgrade. Question, how big a difference is there between a modern aluminum intake and modern carb as opposed to keeping the vehicle historically correct with a period correct cast iron intake and carb ? Thanks for your replies.

It kinda depends on how you intend to use the car and its current running condition. For a cruiser that will remain mostly stock there is nothing wrong with a good running 2V Cleveland. My dad had one and my brother and I drove the wheels off it in high school. No aftermarket intake will make more low rpm torque than the stock cast iron.

If your 2V carb is in tough shape or you plan on future upgrades then an Edelbrock performer and a 600 cfm vacuum secondary carb is probably the way to go.

 

[c9zx]

+1 on TommyK's post. If you are talking about putting an OEM 4V cast iron intake and a period correct 4300D carb on on it, "forgetta bout it". You can always keep the OEM intake and carb in case you ever want to go back.

Chuck

 

[rottenralph]

You could also just get a good performance 2 barrel and save some time. Holley 500 cfm may be the ticket.

 

[judge]

If you want some seat of the pants performance, might want to consider a 3:56 gear. It makes an awesome difference.

 

[CZ-75]

Edelbrock performer intake manifold with a good carb makes a nice difference.

 

[c9zx]

The 500 cfm may provide some improvement but, comparing to the 4V flow vacuum standard of 1.5 inches of vacuum vs. the 2V flow standard of 3.0 inches of vacuum, it works out to about 356 cfm on the 4V standard. However neither of the current rating systems are wet flow numbers. And the measurements are taken on one venturi and multiplied by the number of ventures. And what vacuum an individual engine has at WOT is somewhat variable. So who knows what anything really flows on a given engine and car combination. Perhaps that is why Braswell doesn't assign cfm numbers to their carburetors. Chuck

 

[naa10104]

+1 on TommyK's post. If you are talking about putting an OEM 4V cast iron intake and a period correct 4300D carb on on it, "forgetta bout it". You can always keep the OEM intake and carb in case you ever want to go back.

Chuck

Hi, thanks for the reply, just curious, why are you against the period correct stuff ? To hard to find or don't perform well ? Please educate me ... thanks

 

[Mikes73]

I went against the grain by going with the Edelbrock RPM air gap intake vs the regular performer intake on my 2V cleveland and I'm glad I did, this thing will get rubber and chirp the tires through 1st and 2nd with light throttle even with the pathetic 2.75 gears and an FMX automatic transmission. If you want to look period correct just paint the manifold "old ford blue", with the factory air cleaner on top I doubt anyone would notice the intake isn't period correct. If your car has ram air please disregard my post due to clearance issues

 

[c9zx]

+1 on TommyK's post. If you are talking about putting an OEM 4V cast iron intake and a period correct 4300D carb on on it, "forgetta bout it". You can always keep the OEM intake and carb in case you ever want to go back.

Chuck

Hi, thanks for the reply, just curious, why are you against the period correct stuff ? To hard to find or don't perform well ? Please educate me ... thanks

I'm not against period correct stuff at all but, it must work well for me to use it. If you put an OEM 4V iron intake on 2V heads there would be a huge port mis-match between the heads an the intake. You might get it to seal somehow but it would not work well at all. Compare intake gaskets of 2v and 4V. I'm sure there are a few Super stock racers who can make the 4300 series of carbs work well, I just haven't found them or know anyone who has. If you want to use a 70 or 71 OEM 4V iron intake with a square bore, after market carb on 4V heads, that works reasonably well if you enlarge the primary bore size slightly to match the secondary bore size. A open spacer helps things along above 5000 RPM. Let me know what you want to do and I'll help where I can. Chuck

 

[Kit Sullivan]

A couple of issues: if you want a period-correct set up, you will have to change the 2V heads to 4V heads also. No factory 4V manifold will work with original 2V heads. That will raise your expenses considerably.

I disagree that an aftermarket aluminum 4 barrel manifold and carb cannot make more low end torque than a stock 2V set up. Totally disagree.

A nice mid-rise dual-plane aluminum intake (,Edelbrock "Performer") with a matching carb will make more power than a stock 2V set up for the entire range. Do not "overcarb", the classic and never-ending mistake made by novice and pro alike. A nice little 650-700 cfm 4barrell and aluminum intake on an otherwise stock 351 2V engine with stock manifolds will have awesome throttle response, awesone low end torque and great performance throughout the entire RPM range.

Stay away fron 750 cfm and larger carbs on that motor...you won't be sorry.

 

[1972MustangSVH]

What he said... It's the 21st century, you want the look, go with the look, you want performance, they make it, go with it, they made it for a reason. I'm hoping there was something profound in all that.

 

[gsinger1]

Had one years ago. Dropped a Holley 650 and edelbrock jr on it. Worked pretty good until I discovered the joys (read time consuming) of port and polish on the heads. Woke the thing up like nothing else

 

[kidwithfastback=fast]

What he said... It's the 21st century, you want the look, go with the look, you want performance, they make it, go with it, they made it for a reason. I'm hoping there was something profound in all that.

I agree totally. But I also have a saying that I live by:

"When choosing how to build your ride, you must decide between wanting to go fast, or look good. But in my opinion, Going fast IS looking good"

 

[1972MustangSVH]

Why do you carry that .45? Cause they don't make a .46

I carry a .45 because a cop is too heavy. :banana:

 

[c9zx]

Why do you carry that .45? Cause they don't make a .46

I carry a .45 because a cop is too heavy. :banana:

Plus you can probably shoot better than the cop can.

What he said... It's the 21st century, you want the look, go with the look, you want performance, they make it, go with it, they made it for a reason. I'm hoping there was something profound in all that.

I agree totally. But I also have a saying that I live by:

"When choosing how to build your ride, you must decide between wanting to go fast, or look good. But in my opinion, Going fast IS looking good"

You can have both but, it takes a lot of effort and a considerable amount of time and money. Chuck

 

[naa10104]

+1 on TommyK's post. If you are talking about putting an OEM 4V cast iron intake and a period correct 4300D carb on on it, "forgetta bout it". You can always keep the OEM intake and carb in case you ever want to go back.

Chuck

Hi, thanks for the reply, just curious, why are you against the period correct stuff ? To hard to find or don't perform well ? Please educate me ... thanks

I'm not against period correct stuff at all but, it must work well for me to use it. If you put an OEM 4V iron intake on 2V heads there would be a huge port mis-match between the heads an the intake. You might get it to seal somehow but it would not work well at all. Compare intake gaskets of 2v and 4V. I'm sure there are a few Super stock racers who can make the 4300 series of carbs work well, I just haven't found them or know anyone who has. If you want to use a 70 or 71 OEM 4V iron intake with a square bore, after market carb on 4V heads, that works reasonably well if you enlarge the primary bore size slightly to match the secondary bore size. A open spacer helps things along above 5000 RPM. Let me know what you want to do and I'll help where I can. Chuck

Thanks for the info., appreciate it, might contact you later for more information.

 

[Dave72Rcode]

happy you found the power you wanted...

and if you wanted more performance down the road and a period correct look, perhaps, you can consider the 4V iron heads and the matching factory intake. people are always selling them cheap on Craigslist. Open chamber 4V heads ($200-$400) are cheapest and work well on 91 octane pump gas. a simple Edelbrock 750 carb ($300-$400) will work good out of the box and still fit under your original air cleaner.

but on top of that, you will need the heads prepped like a good valve job with hardened seats + assembly, new stainless steel valves, springs, locks, retainers, cam, and exhaust manifolds or headers... budget $1000-$1500. so for about $2000-$3000 or so, you might be to get as much as 400 HP +- (sae gross) like i did... and look stealthily stock..

good luck on your build...