Simplify your intake system: one 4 barrel!

[rouxroux]

I've used setups like this before on Corvair engines (IECO made them), both on the 2 carb and 4 carb engines. The only problem I ever had was getting sufficient carb heat in the winter. Sure was alot easier than rebuilding/synching 4 Rochesters!

[EarlyPorsche]

You guys forget that a holley has a CHOKE. Chokes are needed on daily driven cars for sure.

[James Brown]

what do you guys think of two weber 2 bbl's on that set up. should fix the float problem and look kinda cool?

[TRE Cup]

go drive that thing at night or during a cool day- you can refrigerate anything attached to the intake below the carb= it ices up
same issue with the corvair single 4 bbl conversion- left us sitting by the side of the road till the tubes warmed up
bad idea

[jluetjen]

... or how about a Rochester TBI injection system off of a Chevy Luv pick-up truck! No wait, with a little bit of work you could put on a Solex updraft carb from a Maserati race car, or better yet how about a set of 6 Stromburg side-drafts from a Jag? SU/Hitachi's off of a 240Z?

And then there are those really cool floatless carbs from Solex. Oh yeah -- Porsche tried those, and they didn't work as well as the Webers or Zeniths.

[Formerly Steve Wilkinson]

Why do you think chokes are needed "for sure" on daily drivers? I have PMOs--no chokes--on a car I use all year round except when it snows, and the correct accelerator-pump use makes starts reasonably easy, first of the day. (And thereafter, starting is absolutely normal.) In fact my daughter is better at starting it than I am; she can usually catch it on the first attempt.

I'm not saying it's anything like as easy as a modern FI car, but I wouldn't discourage somebody from trying to drive a chokeless car. It's an urban myth that they require chokes, just like it's an urban myth that carbs require constant tuning.

[Dixie]

...and suck for dealing with g forces. You can easily set it up for acceleration forces but dealing with forces from all directions will cause float level problems.

As you stated.... "BBBZzzzz..... Thanks for playing." For a Holley equipped car turning corners, you simply need a Holley with center-hung floats, and extended jet tubes.

What the heck do you think Trans-Am cars ran in the '60s? What do you think NASCAR runs today?

[RarlyL8]

I used to have a '73 Widebody hooliganmobile with 40mm Weber and Supertraps. That was the quickest revving coolest sounding car I ever owned. On a 20* day it would fire up and sound like an Indy car as I pumped the trottle as fast as I could to keep it running until it warmed up.

And now for something completely different ...

[James Brown]

is that a 2bbl holey?

[James Brown]

hear is a holley for NASCAR with +- 3g capability of supplying fuel at any angle

850 CFM might be a little big but for $1200 bucks, it's yours!!!!!!!!!

[sc_rufctr]

Originally Posted by Formerly Steve Wilkinson

Why do you think chokes are needed "for sure" on daily drivers? I have PMOs--no chokes--on a car I use all year round except when it snows, and the correct accelerator-pump use makes starts reasonably easy, first of the day. (And thereafter, starting is absolutely normal.) In fact my daughter is better at starting it than I am; she can usually catch it on the first attempt.

I'm not saying it's anything like as easy as a modern FI car, but I wouldn't discourage somebody from trying to drive a chokeless car. It's an urban myth that they require chokes, just like it's an urban myth that carbs require constant tuning.

Back in the day when I owned an air cooled beetle it was common practice to disable the choke.

The idea was if it got stuck open the extra fuel would wash away the oil from the cylinder walls. The theory was this lead to reduced engine life but that was a subject of much debate for a long time...

Thinking back it was never really hard to get the car started. Two pumps of the gas peddle and then turn the key. As soon as it fired you then press part throttle to keep it idling. You had to idle it that way for about 3 minutes and then you were good to go.

[911pcars]

Originally Posted by James Brown

what do you guys think of two weber 2 bbl's on that set up. should fix the float problem and look kinda cool?

What do you guys think of one throttle bore per cylinder (total of six)? Each throttle bore delivers the same amount of air/fuel to each cylinder; Such an animal could incorporate three throttle bores in one housing with a shared throttle shaft so throttle movements remain in sync; install the multiple throttle bore assy. directly over each intake port on the bank for good throttle response. Each throttle bore has its own accelerator pump. And to make it even more exciting, provide a wide range of removable air bleeds, emulsion tubes, fuel jets and venturis to fine tune the fuel delivery for a wide variety of engine displacements and operating conditions.

I'd pay money to have a carb. setup like that. Maybe Holly will make one for us.

Improvements are welcome, but sometimes re-inventing the wheel isn't necessary.

Sherwood

[James Brown]

your talking PMO's! full circle

[911pcars]

Originally Posted by James Brown

your talking PMO's! full circle

Existing Webers and PMOs. Yes.

Sherwood

[Quicksilver]

Originally Posted by James Brown

hear is a holley for NASCAR with +- 3g capability of supplying fuel at any angle

850 CFM might be a little big but for $1200 bucks, it's yours!!!!!!!!!

I wouldn't exactly call that a Holly. I would call that a huge bag of tricks that started out as a Holly. They can be made to work but open up the wallet. The core problems are that the width of the float chamber must be dealt with and the vent location must be worked around..
BTW - That carb won't work 3 Gs in any direction. It can be made to work well at 3 Gs in one direction: left or right. Under hard braking it won't work well on race cars but they don't care. They don't care about mixture problems under braking as that only causes burbles and backfires. Besides every other car on the track has the same carburetor mandated by the rules so who cares? If NASCAR allowed any type of injection how many cars do you think would have carbs?

I have actually built Holly racing carburetors. I still have some in the garage. (The 390cfm setup for the 3.5 liter Olds would probably work pretty good for the craigslist manifold.) Setting them up for road racing was work. Getting them to work on a road course with race tires was irritating.

Here are a few tricks to pull out of the bag...
- If it has side feed floatbowls (like the craigslist ad) replace them with center hung floats. (as pictured above)
- Put in the plastic internal vent extensions to reduce fuel sloshing out the vents. (Most of the performance Hollys with center feed floats have them from the factory since the early 80s)
- If the engine is flooding under braking because of fuel sloshing out of the secondary vent you can connect the 2 float vents with a loop of rubber tube with some small slits at the very top. That will let the fuel slosh into the other float bowl.
- Soldering extension tubes into the jets is a given. For a circle track application the tubes can actually be angled towards the right side of the float chamber.
- In extreme cases try movable jet pickups made with model airplane fuel hose and drilled out model airplane "clunker pickups".
- Replace the brass floats with foam floats that can be trimmed to deal with the specifics of the fuel control problem.
I could get the craiglist thing to work fairly good with some work and parts that I have on the shelf in the garage but I don't feel a need to punish myself.

Basically the real world solution to the problems involved is to get a copy of Stock Car Magazine and call a few carb builders from the ads in the back to get a carb that has seriously been gone through. Once you have that ($$$) starting point you can then start tuning it to the engine.
. . .
Or you can go with a bolt on solution that is known to work. PMOs, CSI, MFI, or my favorite hot rod solution: Megasquirt.

[Quicksilver]

Originally Posted by sc_rufctr

. . .
Thinking back it was never really hard to get the car started. Two pumps of the gas peddle and then turn the key. As soon as it fired you then press part throttle to keep it idling. You had to idle it that way for about 3 minutes and then you were good to go.

I learned to heel-toe by driving a car with no choke during winter in Alaska. I didn't know it was a 'technique'. I was just trying to keep the stupid thing from dieing.

It really helped out later when I learned there was more to driving then aiming the car...

[kidrock]

Way back in the day, Holley made a 2bbl carb for VW called the "Bug Spray". Actually a very decent carb and juiced up my Bugs and Buses very nicely.

I realize that I'm comparing apples and oranges here...but it seems the general consensus on this thread is that the 4bbl has many disadvantages for an air-cooled flat six.

Maybe there is a more suitable 2bbl out there? Maybe someone has experimented with one and can share their experience?

[Aurel]

Maybe a modification of the fan shroud to cover the intake pipes would allow such a setup to work...

[911pcars]

My Camaro buddy sent me this regarding the Holley 4-barrel carbs:

"I installed a Barry Grant Mighty Demon to replace my Holley Double Pumper.

More adjustments such as replacable idle air bleeds, idle feed restrictors, high speed air bleeds, and annular fuel boosters instead of dog leg boosters in the holley. All this means is you can fine tune the Demon to a higher level for much less money than a Holley. The demon annular booster fuel dispersion at low to midrange rpm is awsome. Much better low end response than the holley. The Demon copied all of the Holley's strong points and then made it better for a lot less money."

FWIW.

Sherwood

[RWebb]

Originally Posted by 911pcars

What do you guys think of one throttle bore per cylinder (total of six)? Each throttle bore delivers the same amount of air/fuel to each cylinder; Such an animal could incorporate three throttle bores in one housing with a shared throttle shaft so throttle movements remain in sync; install the multiple throttle bore assy. directly over each intake port on the bank for good throttle response. Each throttle bore has its own accelerator pump. And to make it even more exciting, provide a wide range of removable air bleeds, emulsion tubes, fuel jets and venturis to fine tune the fuel delivery for a wide variety of engine displacements and operating conditions.

I'd pay money to have a carb. setup like that. Maybe Holly will make one for us.

Improvements are welcome, but sometimes re-inventing the wheel isn't necessary.

Sherwood

contender for best post of '09!