Blow Through Vacuum sec Carb?

my mind is running in circles, i have read you can and you cant. But what if it was pressurized like by using a VORTECH SUPERCHARGER CARB ENCLOSURE? would one work then? the only reason is this. i want to eventually do a blow through turbo setup on my 73 after i get the new motor in. the motor is a roller block 302 stock bore with ported RPM edelbrock heads, Xcam, etc. But here is the kicker, I am using a K code intake manifold and an AutoLite 600 carb backed by a t5 5 speed...I know I know but before you all start judging this is why. I am going to make the motor look as stock as possible, stock exhaust manifolds, intake, carb, air cleaner, valve covers, etc. i just want to claim that its stock. but then i got the idea of turboing it for fun just to have the power when ever i wanted it instead of filling a bottle like the race car will be. so im just tryin to do my research to see what will work because even with the turbo i want to claim that its stock with just a turbo so people will only expect 300hp or so instead of the 500+ that it could and might make. please feel free to put in your 2 cents.

thanx

 

i guess if carb is in a box then the vac secondary would open. dont know how well it would work. you can get a double pumper and do the hanger 18 mods referenced on the turbo forums for allot less than messing with trying to get the vac. secondary carb work.

 

Since the secondary opens with venturii vacuum and not manifold vacuum you can have the carb converted to blow through operation.

 

thanks for your help...you think CSU can do it?

 

The vacuum secondary will not work..... Call CSU and I am sure they will tell you the same..... The secondarys work by the air flowing through the venturi and which creates a vacuum on the secondary diaphram which opens the secondaries..... The problem is once you make boost pressure the secondary diaphram will go from a vacuum to pressure and close the secondaries.....

 

Give CSU a call - The pressure in a venturii is a pressure differential caused by the velocity of the flowing through it and it works regardless of pressure. (otherwise your siphon gun wouldn't work at high pressures and it does better at higher pressures)

 

as long as the whole carb is in a pressurized box the vacuum secondary should open.

 

Interesting topic... isn't "vacuum" in this instance just pressure differance?

And if there is no "vacuum" accross the carb's venturi, how does the fuel flow into the intake?

 

fuel flows out of the bowl of carb from the pressure differental in the float bowl to the venturii. so if you run a boosted blow through carb you rout the boost into the float bowls along with through the carb. the same principal should apply to the vac. secondary canister on the side. if it has boosted pressure on bottom it should work.

 

You are correct there is no such thing as a vacum. What most consider a vacum is just a low pressure area.

 

The secondary diaphram will be pressurized effectivly holding the secondaries closed, you could disconect it and run with a mechanical linkage but it would be instant lean when you get in the loud pedal hard



To the o/p why not just put a double pumper on it since in an encloser you will never see the carb? The autolite 4100 is a very poor choice for a performance app, even more so in a boosted application and it is not going to enrich enough under boost pressure no matter what you do to it , plus you have to deal with the brass floats crushing, tiny needle seats,no way to tuine the pcvr channels, air bleeds and the secondaries.


And unless its a 58 model carb with 1.28 venturies it isn't close to 600 cfm either. Your already giving up alot of usable power with the intake and carb but I bet it gets great mpg. Your already on the edge I bet its dead lean in power


Just my honest opinion I've had several blow through cars

 

no thats not true. if the vac. secondary is in the "box" it will see a pressure differental under high load and open.

now i totaly agree that its not even close to being the right carb for a blow through application.

 

was just a thought...and it is forsure a 600cfm autolite not a 480cfm. i had my friends at our local carb shop verify that it was. he has been building carbs for over 35 years im pretty sure he would know. thanks for all the info im in the search for a 600-650 cfm dp.