Typically how is the carb box sealed with regards to the throttle cable? I can't get past all the slow banner **** on the Yahoo Blow Thru Group. It really sucks! (get it? )

 

You could use a cable gland ... as used for passing electrical cables through explosion proof bulkheads ... I don't know where you can buy them in the states but they would be the best solution



basically you pass the cable through and when you tighten it up it grips and seals round the cable

I think you want to be looking for glands with an Ingress protection rating of IP68 which is the highest and should provide an air tight seal

I'm not sure how you stop air from leaking up the cable though

 

Why are you sealing it that far down?? Seal it to the top of the carb. Build a plate that sits up there secured by the center nut of the carb.


Just joking. Let me do some checking i think i iknow a way.

JR

 

No I don't get it.

I don't know why you're bothering with a box... So much extra effort for reduced effectiveness...

 

Ehn?! Did someone say blow-thru? http://store.summitracing.com/partdetail.asp?part=27012

 

Waddaya mean?

 

You have to seal the throttle cable, the choke cable, the hot start assist cable, the OMP rod, you have to deal with the carb being in a box (very hard to get at it to change jets or whathaveyou), and you have that much more volume between the compressor and the carb.

Meanwhile, with a carb hat/bonnet, you just have to de-reference the secondaries (easiest way: make the secondaries mechanical).

 

Not to be my usual combative self, peejay- as I've always demonstrted utmost repect for your knowledge; But- What the **** are you talking about? You were one of the people that turned me on to the blow-thru "carb-ina-"box set up!

And just who in their right friggin mind would slap a 1.5 liter displacement blower on their 12A, and bother to keep stupid **** like the choke and hot start assist?!?! If you can't get the thing started, you should'nt own it!

I'm making the box myself, and as I've said in the past, I'm using cam levers like those found on bicycle wheels, to hold the lid on, yet be able to quickly remove it.
The box surrounding the carb is not going to cause a boost drop!

Carb hat?!?! I'll be blowing fuel back into my pump, as well as out every frigging orifice in the carb! The thing will leak like a coked up rhino that was shot with a ****** tommy gun! (My Dennis Miller thing goin on here!)

And before anyone jumps the "Well you asked..." gun, what I asked was in a blow thru set up, what is typically done to seal up the throttle cable. Now any ******* can use brass fittings and whatnot...A silicone caulk gun for Gawds sake. But the leaking thru the cable - is that just taken at a loss and compensated for because it's not that much? Or are there specially sealed cables for this purpose?

Maybe there's something I overlooked. Tell me how I can do this without putting my whole carb in a sealed box...
The blower will be pullied for 14 psi. I plan to control it down to reasonable pressure from inside the cockpit using a modded POV, being able to crank up the boost whenever I want, as well as manually over ride the by-pass valve but introducing 14 psi to the top of the carb does'nt just send that pressure down the venturis...It also blows it into the emulsion tubes and idle air bleeds! So you need the pressure to be equally acting on the floats and fuel bowls. This keeps everything in check. The basically you tune the carb for about ten miles below sea level! But all acting pressures are consistant.

...No?

 

For what it's worth, I've ALWAYS been against the idea of a boxed carb. Don't believe me? Go back and search.

No matter if it's boxed or just has a bonnet, you'll have to reference the fuel pressure to above-carb boost pressure. Putting the carb in a box won't solve that problem all by itself.

As far as leaks... I don't buy that. Plenty of people put hats on stock carbs without special sealing on the throttle shafts with NO PROBLEMS. Think about it... if boost leakage was that big of a problem, then you'd have massive vacuum leaks! Pressure is pressure, whether it's 14psi trying to force its way out or 14psi (atmospheric pressure) trying to force its way IN.

 

I did. Yer right.

peejay
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Status: Online!
Registered: May 2001
Location: Cleveland, Ohio, USA
Posts: 5766

"Waitaminute... you plan on making this blow-through? I say DON'T DO IT. What happens when you shift at 8k and let off the throttle? The blower is trying to force 12,000 liters of air (or whatever you decide for pulleys) per minute into a closed pipe! At the very best, this will result in blowing the hose off or breaking the belt. At the worst... well the E-shaft snouts are pretty weak on our cars and are known to bend/break when you put a blower on. "


01-21-02 01:50 PM

 

Not a new topic. Some history. www.vs57.com/carb.htm