I'm running a Carter/AFB 750 cfm carb on a Typhoon Dual Plane intake and a 4 hole 1"spacer plate with 40P heads with upgraded springs. My motor seems to have a power band from bottom to top. I'm basically running a RV cam with 284 duration Crane cam. My bottom end is a '85 HO block decked 15 thousandth and bored 30 over with 11:1 compression 30 over Chevy 350 pistons. Motor Trend had a article about a 400 HP 302 on pump gas. I've changed a few things along the way.
Eric's doing a Dominator flanged dual plane for David (not an adaptor, he's done that), but that's going on a motor that needs a Dominator. Henry Ford put the first production dual plane on the '34 Ford for smoother running, the '32 and '33 had a single plane with a single barrel carb.
In my opinion, if you have the correct size carburetor for your combination it only makes sense that it should work equally well with either manifold because not all 8 cylinders are filling with air fuel mixture at the same time. Most of the time there should be roughly the same amount needed on both sides of the engine. If the carb is functioning properly and is the correct size for the application there is no reason for different size carbs for dual or single plane manifolds.
Richard: Thank you for this topic. I'm working to inverse my torque to hp readings, so that, I have higher hp than I do have in torque. I thought that when I changed the intake to an open plenum intake, I would do this. Volumetric efficiency says that I need a smaller carburetor. I'm running a 650cfm, and I need a 600cfm for optimum performance.(double pumpers in both cases). I using a Crower cam with 9.81:1 compression ratio with 170cc runners and a 62cc head.. Is this too restrictive a combination?
When I was drag racing my street car regularly, I switched from a 750 to an 850. The car is a '69 Chevelle with a 468 and rec port heads and factory dual plane intake with a 1" spacer. It ran better, faster. Now it is just a cruiser and I really could go back to a 750. But it starts and runs so good I hate to mess with it.
I think that the dual-plane can use more carburetor is because the signal or let's say the amount of air pulling through the divided manifold has a higher Peak CFM and a lower lower CFM from each cylinder pulse even though the total is the same
A great myth that i also used to believe. What the "big carb dual plane" myth really boils down to is crutching poor airflow in the typical as cast dual plane plenum. The big carb generally does help the dual plane at WOT simply by slowing air speed out of the carb where it has to make the 'short turn' into the plenum/runner transition area. The slower airspeed out of the bigger carb helps the air turn and help feed the runners enough to increase the WOT hp. You can test this on a flow bench and at the track. If you then rework the intake manifold plenum and runner entry(not talking adding slots, cut outs, spacers) to help air flow where the dual plane plenum/runner entry suffers you can get the WOT hp back while using the smaller carb which in turn also has better driveability at low/mid throttle and rpms. So no the engine does not need a bigger carb with a dual plane but a bigger carb can usually crutch an as cast dual plane. The engine is just looking for airflow relative to its requirements.
@richardholdener1727 , there's a old school trick to a carb setup. You take a piece of wire screen and put on bottom of the spacer plate which helps to vaporize the fuel going into the intake. Therefore the fuel is better distributed along the cylinders.
I remember years ago an automotive teacher told us the rough estimate for what carb to use is double the cubic inch. 302 =625, 350= 700 , 360 = 725. I do know my 360 likes a 750 over the 625. But I definitely got better gas mileage with the 625. I do have a duel plane intake with a 1 inch nitrous spacer under the carburetor.
that completely removes the other half the equation. its displacement and rpm. carbs are sized by air. a 4000 rpm stock engine and a 7000rpm race engine needs different carbs. displacement times rpm divided by 3456 this is the equation for how much air the engine will move. 302 x 6000 / 3456 = 524cfm
@mustang351c4 Yes, I came to explain this, and also one must consider the modifications done to the engine. Take a 1978 2BBL 302 that makes 130hp, and you do nothing to the cam/heads/exhaust, putting a Single plane and slapping a 750 on it (I have seen it done) and thinking it's gonna "Double the power" and be fun on the street. - They have a miserable engine that might make 20hp over stock but will have drivability like a Frozen Turd. - a 400CFM 4bbl is plenty on a 1978 302 smog turd. (Still flows more than the cheesy 2BBL)
Engine masters did a carb test on a dual plane Blueprint 383 years ago and found a point where a carb that was too big was actually hurting power. The 750 was a perfect match and still had a good vacuum signal. The intake vacuum with an 850 got to .5 lbs under wide open throttle and was down on power. Apparently David Vizard doesn't watch engine masters.
HA !!! Youd better guess again as we aint racin dynos bud !!! Real World et and mph IS the name of the game !!! You Cant clusterfck it all together then think you know ALL !!! Real World is entirely different than what those guys on enginemasters could or even would experiance on the road . Speaking of experiance id say you lack clout to make as foolish of a statement as to insult an engineer whose spent a lifetime doing this sort of testing and much deeper testing . Too many variables for YOU to qualify as a Credible Critique bozo with Nothing to back him !!!
A 750 cfm carb on a dual plane on a 350 ci. If you want to divide the carb in half in your head to make your arguement, just remember to divide the engine in half also. Now you have 2-375 cfm carbs on 2-175 ci engines. Which is exactly the same thing as a 750 cfm on a 350. And round we go..lol.
i f a 400 hp engine only need s a 600 cfm Carb, why then when I remove my 600-cfm street driver carb on my 340 hp 302, replace it with My 750 Dubble pumper my car will run 2 tenths quicker with the larger carb. I don't care about Dyno numbers because i don't race dyno, but I do care about 1/4-mile times and they go down when the carb is bigger. only needing a little carb is proven BS.
You won't read this I'm sure, but that guy ( powertech 10) british guy, included this argument into his single plane complaint that cylinder pressure reversion during valve overlap after combustion, negatively effects the next cylinder in the firing order. Like opposite corner cylinder to opposite corner cylinder firing order (chevy). He claims, that with a dual plane, that pressure wave can't come up and affect the next cylinder intake flow air pressure because of the center divider. From there hecwent on to say how he believes there is more power to be made over a single plane, by using a dual plane with huge carb. Would love to see the evidence for his claim. Especially with the cylinder interference on another cylinder.
(I read every comment) I don't know how what he says dictates a bigger carb, and the robbing of adjacent cylinders is firing order dependent and would be more pronounced on a single plane
@richardholdener1727 ty very much for the response. I'm honored. I value your videos. I may not have explained it properly. So I found his video I spoke of. 4 moths ago, David vizard video titled "2plane intakes-good- but could be way better". Hope it clears up what was trying to say.
You sure are consistent. :) 1. Every cam is a turbo cam. 2. Boost is just restriction. 3. And now this. Half a big block, 272 CID or more, will be perfectly fine with a 2 barrel carb. :) ruclips.net/video/sXPN2McLxxA/видео.html ruclips.net/video/74HvdyUdnFs/видео.html
Sounds like you need to put a 400hp motor on the dyno and test a bunch of carbs. 😂
I'm running a Carter/AFB 750 cfm carb on a Typhoon Dual Plane intake and a 4 hole 1"spacer plate with 40P heads with upgraded springs. My motor seems to have a power band from bottom to top. I'm basically running a RV cam with 284 duration Crane cam.
My bottom end is a '85 HO block decked 15 thousandth and bored 30 over with 11:1 compression 30 over Chevy 350 pistons.
Motor Trend had a article about a 400 HP 302 on pump gas. I've changed a few things along the way.
Eric's doing a Dominator flanged dual plane for David (not an adaptor, he's done that), but that's going on a motor that needs a Dominator.
Henry Ford put the first production dual plane on the '34 Ford for smoother running, the '32 and '33 had a single plane with a single barrel carb.
In my opinion, if you have the correct size carburetor for your combination it only makes sense that it should work equally well with either manifold because not all 8 cylinders are filling with air fuel mixture at the same time. Most of the time there should be roughly the same amount needed on both sides of the engine. If the carb is functioning properly and is the correct size for the application there is no reason for different size carbs for dual or single plane manifolds.
Edelbrock we want a dual plane intake with 4500 inlet Air gap and dominator
Richard: Thank you for this topic. I'm working to inverse my torque to hp readings, so that, I have higher hp than I do have in torque. I thought that when I changed the intake to an open plenum intake, I would do this. Volumetric efficiency says that I need a smaller carburetor. I'm running a 650cfm, and I need a 600cfm for optimum performance.(double pumpers in both cases). I using a Crower cam with 9.81:1 compression ratio with 170cc runners and a 62cc head.. Is this too restrictive a combination?
if you make more hp-you need a bigger carb
@@richardholdener1727 Thanks for the reply!
When I was drag racing my street car regularly, I switched from a 750 to an 850. The car is a '69 Chevelle with a 468 and rec port heads and factory dual plane intake with a 1" spacer. It ran better, faster. Now it is just a cruiser and I really could go back to a 750. But it starts and runs so good I hate to mess with it.
What did your 660 times look like to the overall?
I think that the dual-plane can use more carburetor is because the signal or let's say the amount of air pulling through the divided manifold has a higher Peak CFM and a lower lower CFM from each cylinder pulse even though the total is the same
198 👍's up Richard thank you for sharing 🤗
Thankyou for your dedication to reading every comment richard, that's a hard job!
You bet
In my opinion the duel plane does better at high rpm due to velocity. Single plane has more of a balanced plenum with less velocity.
I wonder if it has something to do with the signal underneath the carburetor in relationship to jet size
Rich, has there ever been a manifold that is adjustable between dual and single plane on the fly?
no-but yes on changing runner length
Have you ever tested the Typhoon Dual Plane intake? In some research I did said it was as good as a Victor Jr intake.
A great myth that i also used to believe. What the "big carb dual plane" myth really boils down to is crutching poor airflow in the typical as cast dual plane plenum. The big carb generally does help the dual plane at WOT simply by slowing air speed out of the carb where it has to make the 'short turn' into the plenum/runner transition area. The slower airspeed out of the bigger carb helps the air turn and help feed the runners enough to increase the WOT hp. You can test this on a flow bench and at the track. If you then rework the intake manifold plenum and runner entry(not talking adding slots, cut outs, spacers) to help air flow where the dual plane plenum/runner entry suffers you can get the WOT hp back while using the smaller carb which in turn also has better driveability at low/mid throttle and rpms.
So no the engine does not need a bigger carb with a dual plane but a bigger carb can usually crutch an as cast dual plane.
The engine is just looking for airflow relative to its requirements.
we have not seen that
Pressure drop due to plenum volume Affects velocities and signal strength dual plane verses single plane .
You said about running a spacer on a dual plane intake changes it. Actually it doesn't if you use a 4 hole spacer.
A Vett uses a 350/375 HP motor.
the signal to the carb is still altered with a 4 hole spacer compared to none
@richardholdener1727 , there's a old school trick to a carb setup. You take a piece of wire screen and put on bottom of the spacer plate which helps to vaporize the fuel going into the intake. Therefore the fuel is better distributed along the cylinders.
@richardholdener1727 , say hello to Frankenstein 😁
ruclips.net/video/TzkPcQvObd0/видео.htmlfeature=shared
I remember years ago an automotive teacher told us the rough estimate for what carb to use is double the cubic inch. 302 =625, 350= 700 , 360 = 725. I do know my 360 likes a 750 over the 625. But I definitely got better gas mileage with the 625. I do have a duel plane intake with a 1 inch nitrous spacer under the carburetor.
that completely removes the other half the equation. its displacement and rpm. carbs are sized by air. a 4000 rpm stock engine and a 7000rpm race engine needs different carbs.
displacement times rpm divided by 3456
this is the equation for how much air the engine will move.
302 x 6000 / 3456 = 524cfm
@mustang351c4 Yes, I came to explain this, and also one must consider the modifications done to the engine.
Take a 1978 2BBL 302 that makes 130hp, and you do nothing to the cam/heads/exhaust, putting a Single plane and slapping a 750 on it (I have seen it done) and thinking it's gonna "Double the power" and be fun on the street. - They have a miserable engine that might make 20hp over stock but will have drivability like a Frozen Turd. - a 400CFM 4bbl is plenty on a 1978 302 smog turd. (Still flows more than the cheesy 2BBL)
Engine masters did a carb test on a dual plane Blueprint 383 years ago and found a point where a carb that was too big was actually hurting power. The 750 was a perfect match and still had a good vacuum signal. The intake vacuum with an 850 got to .5 lbs under wide open throttle and was down on power. Apparently David Vizard doesn't watch engine masters.
I'm thinking a 700 dbl ppr jetted and the right boosters would out perform on smaller port heads and duel plane intakes.
HA !!! Youd better guess again as we aint racin dynos bud !!! Real World et and mph IS the name of the game !!! You Cant clusterfck it all together then think you know ALL !!! Real World is entirely different than what those guys on enginemasters could or even would experiance on the road . Speaking of experiance id say you lack clout to make as foolish of a statement as to insult an engineer whose spent a lifetime doing this sort of testing and much deeper testing . Too many variables for YOU to qualify as a Credible Critique bozo with Nothing to back him !!!
A 750 cfm carb on a dual plane on a 350 ci. If you want to divide the carb in half in your head to make your arguement, just remember to divide the engine in half also. Now you have 2-375 cfm carbs on 2-175 ci engines. Which is exactly the same thing as a 750 cfm on a 350. And round we go..lol.
i f a 400 hp engine only need s a 600 cfm Carb, why then when I remove my 600-cfm street driver carb on my 340 hp 302, replace it with My 750 Dubble pumper my car will run 2 tenths quicker with the larger carb. I don't care about Dyno numbers because i don't race dyno, but I do care about 1/4-mile times and they go down when the carb is bigger. only needing a little carb is proven BS.
Your 600 is probably delivering less fuel when the engine wants more. Air flow isn’t the problem.
@joshiek7839 that is misconception nonsense
@@4739-g9c So you don't like facts good on you, It don't fit your bullshit so it isn't relative.
@@4739-g9c please elaborate oh wise wizard
@@4739-g9c No its not. - I am willing to bet if he had wideband he would see the 600 is running lean on top.
Richard would you have a 8.1 chev gen 7 dart intake for sale. I seen you used it on dyno test a while back!
I do not
You won't read this I'm sure, but that guy ( powertech 10) british guy, included this argument into his single plane complaint that cylinder pressure reversion during valve overlap after combustion, negatively effects the next cylinder in the firing order. Like opposite corner cylinder to opposite corner cylinder firing order (chevy).
He claims, that with a dual plane, that pressure wave can't come up and affect the next cylinder intake flow air pressure because of the center divider.
From there hecwent on to say how he believes there is more power to be made over a single plane, by using a dual plane with huge carb.
Would love to see the evidence for his claim. Especially with the cylinder interference on another cylinder.
(I read every comment) I don't know how what he says dictates a bigger carb, and the robbing of adjacent cylinders is firing order dependent and would be more pronounced on a single plane
@richardholdener1727 ty very much for the response. I'm honored. I value your videos.
I may not have explained it properly. So I found his video I spoke of.
4 moths ago, David vizard video titled "2plane intakes-good- but could be way better".
Hope it clears up what was trying to say.
I would think drivabilty would be better with the dual plane..it's all about signal pulling on the carb..
How does the dual plane do it better?
@joshiek7839 more tourqe though lower rpms ,which helps Drivability.
@@woodys74nova well that has nothing to do with your original statement.
@joshiek7839 what don't you understand about my statement? I am glad to explain..signal ?
@@woodys74nova how is a dual plane “pulling a better signal” on the CARBY?
Why does your video freeze at 10.48... Government not wanting bigger carbs on motors ???
I had a 69 Mustang Grande with a 429 two barrel. Isky mega cam. .516 lift, forget duration. Loads of fun. Lots of bragging.
516 isn't mega lift but it didn't take much to make those fords come alive
Put a one inch spacer then your intake is not divided 😂
A dual plane manifold is just two single plane manifolds on an engine half the capacity.
nope
You sure are consistent. :)
1. Every cam is a turbo cam.
2. Boost is just restriction.
3. And now this. Half a big block, 272 CID or more, will be perfectly fine with a 2 barrel carb. :)
ruclips.net/video/sXPN2McLxxA/видео.html
ruclips.net/video/74HvdyUdnFs/видео.html
It’s all about PULSES / SIGNAL ?