Simplify your intake system: one 4 barrel!

[techweenie]

Found this on CraigsList:

http://sandiego.craigslist.org/nsd/pts/1064849266.html

[sc_rufctr]

That is awesome... Would be something to play around with a set-up like that.

I bet it would go hard... But it doesn't look right for a 911 engine bay so that would be reason enough for some people to bag the idea.

Good find

[sc_rufctr]

It's worth $200 for the intake pipes alone... I love the custom CIS box base

[techweenie]

I saw one of these setups years ago, but this one is a bit better developed.

[James Brown]

I think that carb would ice up if you don't heat up the plenum and the tubes

[911pcars]

Due to the distance from the accelerator pump, the engine might experience turbo lag, but without the turbo.

Sherwood

[James Brown]

kinda cool, and cheap!!!

[Porsche-O-Phile]

Tempting... I wonder about putting that on my 2.7... Hmmm. A heck of a lot cheaper than either Webers or (yikes!) PMOs. Ya know what "PMO" stands for right? "Pay More Out".

I have a spare CIS box downstairs. That's giving me some ideas... Surprised more people don't try stuff like this. Seems almost idiotically simple and bulletproof.

[matty74]

that is a damn good idea

[Rob B]

Reversing technology, just like NASCAR. There are lots of reasons not to.
Rob

[berettafan]

the neat thing about it isn't the cost savings but rather the need to only tune one mixture, etc.

not to mention a sniffer machine at the tail pipe would actually mean something!

[sc_rufctr]

All good comments but how would it perform?

Has anybody used a similar setup?

[berettafan]

Doesn't CIS have a common plenum?

[stormmaster]

I had a single carb on my 914 years ago.....it ran fantastic and no more issue with Fuel Injection.

[SpeedracerIndy]

Bob Farmer (Farmer's Automotive), here in Indy fabricates a setup just like that. I have seen it on one of his race cars in the shop. He said it flows better than the common setups, and it is cheaper and easier to tune. I wish I had taken a picture when I was in there a few weeks ago getting my mixture adjusted. Someone in the local area has to have experience with it.

[bkreigsr]

the guy in the booth next to me at Hershey last year had one FS & I got to talk to him about it.
Yes on the turbo lag, with lots of gas fumes in the cabin when driving, and he could not get jets small enough to lean it out for sub 3,000 rpm driving.
He started out at $250 at 6:30am and was at $25 by 3:30pm with no takers.
The carb alone is over $400 new isn't it?
Bill K

[911pcars]

I think that might work okay at a constant throttle opening. As for overall operation, I have my doubts. How does each cylinder receive an equal amount of A/F? Thank you.

40 years ago, someone (EMPI?) manufactured a single 4-barrel carb. conversion for the Corvair and it didn't work as well as the factory setup of two single barrel carbs feeding each bank of three cylinders. Summarize what you will out of that bit of history.

But time marches forward, and I'm not against any attempts at improvement.

Sherwood

[Quicksilver]

BZZZZZZT... thankyouforplaying...

Holly's are easy to tune, produce good power, come in almost any size, are great for muscle cars, ...

...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.

In practice what you get is: A good sticky set of tires and the engine will tend to flood under hard braking as gas sloshes from the vent tubes into the venturis. To get the lateral acceleration problems under control you have to lower the float level but that causes the jets to tend to uncover from sloshing. The core problem is the float chamber isn't very tall and is rather wide. This doesn't work for hard cornering and braking.

Originally Posted by bkreigsr

the guy in the booth next to me at Hershey last year had one FS & I got to talk to him about it.
Yes on the turbo lag, with lots of gas fumes in the cabin when driving, and he could not get jets small enough to lean it out for sub 3,000 rpm driving.
He started out at $250 at 6:30am and was at $25 by 3:30pm with no takers.
The carb alone is over $400 new isn't it?
Bill K

The jet sizing isn't really a problem if you really know how to tune the whole circuit system in the Holly. What he needed to do was drill out the corresponding air bleed to reduce the signal to the jet. Changing the emulsion tubes might be enough to solve this too but they aren't made to be removable. To do this you need to be willing to sacrifice a few carburetors to get it right.

When you are done messing with it you will end up with a system that cruises great but the float system still won't let you corner or brake.

[RWebb]

I did that on a bus motor in the 1970s. It works but not nearly as well as some other options.

And... it has been discussed here before.

In essence, it has the advantage of being cheaper than some other options, but that is about it.

What I like is the cheapo m/c throttle body adaptations that some were playing with. We all know that there are LOTS of wrecked m/c's lying around.

[jluetjen]

If you want an affordable alternative to Webers or PMOs -- get some Zeniths. While they don't have quite as many tuning options as Webers, I'd have to believe that they are certainly better then the Holley in this application given that they were original equipment 911T's for a couple of years.