what carb do you use
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750 vac sec, choke milled, flowed venturi's it has two power valves, that's a first for me!
No bog of the line (sub 2 sec 60') 13.4 at the top @100, it did go 101 on a 13.6 pass..LOL pulls hard until 3rd then just feels like it lays down, you know the feeling...36 deg timing all in no rattles, drives lovely on the street and explodes when you nail it, pure top end thing.
The times tally with some from the States I have seen but the ol' 383 used to go 14.0 at 104 on ave??
Maybe it is me!
No bog of the line (sub 2 sec 60') 13.4 at the top @100, it did go 101 on a 13.6 pass..LOL pulls hard until 3rd then just feels like it lays down, you know the feeling...36 deg timing all in no rattles, drives lovely on the street and explodes when you nail it, pure top end thing.
The times tally with some from the States I have seen but the ol' 383 used to go 14.0 at 104 on ave??
Maybe it is me!
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Anonymous
Alex... I'll put my own money where my mouth is, you give me the entire specs on the car, if there's anything that can be improved on AND reduce times then i'll supply it FOC... if it takes off time then you buy it... if it don't then I buy it....
This would be ignition, fuel system and carb as specced by Don not me
And Dave... unarmed for not much longer... Don is coming over for the Nats next year and if i've got my finger out on the dart then it will be down the track with 2 drivers, me and Don, lots to do and it may not be done but he's going to be there no matter what, i'd actually like to see him ship his own car over for the Nats but thats around ?1200/?1500 round trip.
BTW Alex what date is the Nats as he's bugging me for dates to book flights
This would be ignition, fuel system and carb as specced by Don not me
And Dave... unarmed for not much longer... Don is coming over for the Nats next year and if i've got my finger out on the dart then it will be down the track with 2 drivers, me and Don, lots to do and it may not be done but he's going to be there no matter what, i'd actually like to see him ship his own car over for the Nats but thats around ?1200/?1500 round trip.
BTW Alex what date is the Nats as he's bugging me for dates to book flights
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Cannonball
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there see a good example with alex car he has a 750 and prob similar weight to the cuda, ok his is a 4 speed so will have a crap 60ft but should have better mph at the top end the cuda goes 105-6mph
we also have a 3.23 rear and tight factory verter
i dont dis agree a well sorted mtr needs more carb def start losing a lot off power above 6,000rpms with a small carb, a good mid 11 sec carb is a 780 vac sec it always won over my 850 double pumper
we also have a 3.23 rear and tight factory verter
i dont dis agree a well sorted mtr needs more carb def start losing a lot off power above 6,000rpms with a small carb, a good mid 11 sec carb is a 780 vac sec it always won over my 850 double pumper
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WATTS RACING TRANSMISSIONS, CLOBBER THE COMPETITION ITS CLOBBERIN TIME
OFTEN OUTNUMBERED NEVER OUTGUNNED,
HEY WHATS THE TOP END ON THAT SUPERSPORTS. UNLIMITED,
I HAVE A NVQW
LIFE GOES PRETTY FAST, IF YOU DONT LOOK ROUND A WHILE YOU MAY JUST MISS IT,
THE PASS IS THE JUICE,
LOVED BY FEW,
HATED BY MANY
RESPECTED BY ALL
What is your top end RPM Alex? I would expect you to pull more than 100mph at that ET so something is amiss. Assuming you are pulling less than 6000rpm you don't need more CFM, and I'd be surprised if a 750 was too much, and I'll stick my neck out and say I think a 600 would slow you down, I've got one if you want to try it, it would be an interesting experiment. I think there will be some extra MPH hiding in the tune up, just need to optimize what you already have.
“It’s good enough for Nancy”
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Cannonball
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Anonymous
If I read it right and the car is manual then it needs mech secondaries
Depending on the duration @ 050 and the intake it needs a 750 Speed Demon with Mechanical Secondaries if it's up to around 240 @ 050 with a dual plane or small single plane. 14/16 ish on the initial
If it's over 240 but below 260 @ 050 it needs a 750 Mighty Demon, these are all mechanical secondaries, initial at 18/20 ish
The distributor would then need to be custom curved as the total would be too high, but this would be dependant on car specs.
The car would also benefit from a Cometic undercarb spacer and gaskets
Also a good look at the fuel system.
Up until recently I had a 750 mighty here and would have lent it for you to play with but I sold it. Got to reorder one anyway for stock so it's up to you if you want to try one
I have a complete ignition kit with distributor you can try if you want, although there is no Vac Can on it so may not be the best choice depending on cam and application, although it is fully adjustable on the total,
Depending on the duration @ 050 and the intake it needs a 750 Speed Demon with Mechanical Secondaries if it's up to around 240 @ 050 with a dual plane or small single plane. 14/16 ish on the initial
If it's over 240 but below 260 @ 050 it needs a 750 Mighty Demon, these are all mechanical secondaries, initial at 18/20 ish
The distributor would then need to be custom curved as the total would be too high, but this would be dependant on car specs.
The car would also benefit from a Cometic undercarb spacer and gaskets
Also a good look at the fuel system.
Up until recently I had a 750 mighty here and would have lent it for you to play with but I sold it. Got to reorder one anyway for stock so it's up to you if you want to try one
I have a complete ignition kit with distributor you can try if you want, although there is no Vac Can on it so may not be the best choice depending on cam and application, although it is fully adjustable on the total,
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Dave-R
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Personal differences apart (sorry for deliberatly winding you up Neil) this is a very interesting thread. We all want the best for our engines no matter what the performance level and we all agree the Demon is a great carb.
What worries me is a direct comparison between a Holley and a Demon because I would put money on the Demon flowing more air than the Holley.
The torque curve of the engine is another factor to consider with carb selection. I don't know but I am guessing that a solid lifter cam would like a slightly smaller carb than a hydraulic cam of the same duration.
Any cam making good torque at lower rpms is going to like a smaller carb. If your engine makes all its power high up in the rpm range I think a bigger carb is the answer.
I could well be wrong but that is the way I see it.
What worries me is a direct comparison between a Holley and a Demon because I would put money on the Demon flowing more air than the Holley.
The torque curve of the engine is another factor to consider with carb selection. I don't know but I am guessing that a solid lifter cam would like a slightly smaller carb than a hydraulic cam of the same duration.
Any cam making good torque at lower rpms is going to like a smaller carb. If your engine makes all its power high up in the rpm range I think a bigger carb is the answer.
I could well be wrong but that is the way I see it.
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Anonymous
Hey Dave, I suspect we're both as bad on the wind up front, don't know about you but I actually enjoy it 
It's a thread on cars that will never get to shotguns at dawn and all that garbage lifes too short for that, different opinions are the basis for all intelligent debate.
This isn't a trick question but why do you guess that a solid would like a smaller carb, i'd say it's the grind and duration at 50 that determines carb size and other variables that also make it not as black and white.
I agree that there is grey areas either side of ideal cfm where the variables demand a slightly different approach
Considering that an engine is only an air pump...air in and air out, with every cycle of the engine it inhales a measured amount of air based on the cubic inches of displacement and exhales exactly the same amount. The variable is the amount of fuel you add to the air and what the combustion chamber does to it.
When you go WOT your opening is a big hole to the intake port, the bigger the hole the lower the velocity or air speed....too big a hole and you lose velocity, this lower velocity and because the valve open time is so short it can't fill to it's max potential or sweep the spent exhaust gases out of the combustion chamber means too big of a carb equals lower horse power/torque output, poor drivability, tip in stumble, poor low end torque and for the Drag Racer a time slip that shows a mediocre 60' time.
If the carb is too small it creates a restriction or vacuum condition in the intake and again the intake valve can't deliver a full charge.
These variances in the vacuum signals send a message to the carb and dictate how much fuel it's going to add to the air rushing through it.
This balance is critical to achieve optimum performance.
This is not a mystical theory but a calculated scientific formula based on:
Load: Weight, gearing, tyre size, trans type and converter stall.
Demand: Cam lift, duration, manifold type, intake runner size, valve sizes, header efficiency, basically the ability of the engine to breath.
Combustion Chamber efficiency: Size and shape of the chamber, compression ratio, swept volume and combustion chamber quality.
Application: Drag Racing, Road Racing, Off Road, Street, Circle Track, Trailer Queen, Grandma's 67 Polara Station Wagon Grocery Getter.
copied off of Dons tech pages
It's a thread on cars that will never get to shotguns at dawn and all that garbage lifes too short for that, different opinions are the basis for all intelligent debate.
This isn't a trick question but why do you guess that a solid would like a smaller carb, i'd say it's the grind and duration at 50 that determines carb size and other variables that also make it not as black and white.
I agree that there is grey areas either side of ideal cfm where the variables demand a slightly different approach
Considering that an engine is only an air pump...air in and air out, with every cycle of the engine it inhales a measured amount of air based on the cubic inches of displacement and exhales exactly the same amount. The variable is the amount of fuel you add to the air and what the combustion chamber does to it.
When you go WOT your opening is a big hole to the intake port, the bigger the hole the lower the velocity or air speed....too big a hole and you lose velocity, this lower velocity and because the valve open time is so short it can't fill to it's max potential or sweep the spent exhaust gases out of the combustion chamber means too big of a carb equals lower horse power/torque output, poor drivability, tip in stumble, poor low end torque and for the Drag Racer a time slip that shows a mediocre 60' time.
If the carb is too small it creates a restriction or vacuum condition in the intake and again the intake valve can't deliver a full charge.
These variances in the vacuum signals send a message to the carb and dictate how much fuel it's going to add to the air rushing through it.
This balance is critical to achieve optimum performance.
This is not a mystical theory but a calculated scientific formula based on:
Load: Weight, gearing, tyre size, trans type and converter stall.
Demand: Cam lift, duration, manifold type, intake runner size, valve sizes, header efficiency, basically the ability of the engine to breath.
Combustion Chamber efficiency: Size and shape of the chamber, compression ratio, swept volume and combustion chamber quality.
Application: Drag Racing, Road Racing, Off Road, Street, Circle Track, Trailer Queen, Grandma's 67 Polara Station Wagon Grocery Getter.
copied off of Dons tech pages
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Dave-R
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We are probably saying the same thing in different ways.Wil wrote:This isn't a trick question but why do you guess that a solid would like a smaller carb, i'd say it's the grind and duration at 50 that determines carb size and other variables that also make it not as black and white.
You are basing your carb selection on duration yes? Well in effect what you are basing your selection on is where in the rpm band the engine is making its torque.
So we are on the same lines. The higher up the scale the engine makes torque the bigger the carb needed.
But solids of the same duration as hydraulics tend to make their torque slightly lower down the rpm scale than hydraulics. Shifting the ideal shift points down too. That could make a slightly smaller carb a better selection.
These are just thoughts off the top of my head. Could be Bananarama!.
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Anonymous
We are saying the same thing but in different ways, the duration at 50 is a sure fire number though, so if the cam selection is right and I will agree that some aren't, the @ 50 figure is certainly the one BG want to know, don't know about the other manfacturers.
If the cam is miles off then it's best changed as no amont of tuning will give optimum results, and surely it's about getting what you have or can afford to have to run at it's best at all times, Russ's charger case in point, low compression, stock motor, stock convertor and a cam that was totally wrong, 750 speed, custom distributor and a cam change and it's a different car
If the cam is miles off then it's best changed as no amont of tuning will give optimum results, and surely it's about getting what you have or can afford to have to run at it's best at all times, Russ's charger case in point, low compression, stock motor, stock convertor and a cam that was totally wrong, 750 speed, custom distributor and a cam change and it's a different car