how do i turbo prep a carb?
Full Member
Joined: Mar 2005
Posts: 215
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From: Iowa
There's alot to it. You may want to pick up Maximum Boost from amazon.com as it has the info on what needs to be done to carbs in general to turbo prep them.
If it's your first time, I recommend practicing on another carb to make sure you can get it right the first try.
If it's your first time, I recommend practicing on another carb to make sure you can get it right the first try.
love the braaaap
Joined: Jul 2003
Posts: 3,771
Likes: 5
From: Bognor, Ontario
Its not as simple on a Nikki as other carbs. A basic list of mods is sealed throttle shafts, solid floats (nitrophyl), mechanical secondaries, drill holes to any sections of the carb that my be sealed off from boost, new gaskets any time the carb top is taken off, there may be some customizing of the air bleed and jet holes to allow holley air bleeds and jets (nikki jets are super expensive and there aren't any other air bleeds). There is probably more that needs to be done, but I can't think of anything else off the top of my head.
standard combustion
Joined: Dec 2001
Posts: 1,374
Likes: 0
From: Twin Cities Minnesota
I never heard you need to seal throttle shafts? And how? Is that something only Nikki needs? If it leaked normally, it would have a engine vacuum leak all the time as it was normally wouldn't it?
It's called blowby. The throttle shafts are not sealed. If they were, the shafts could not turn. There are some tricks to "pressurize" the shafts. Most people don't. You will have a little gas sweat at the shafts. I'm sure at some point Robert will chime in on this.
love the braaaap
Joined: Jul 2003
Posts: 3,771
Likes: 5
From: Bognor, Ontario
To seal the shafts, you can o-ring them and use super strong springs to make sure they return. Another way is to use the boost to pressurize the bore for the shaft and essentially seal it. Its not absolutely critical to seal them, but highly recommended as gas will leak from the shafts and possibly drip onto a hot surface. With a brand new carb this isn't as likely as with an older worn out carb.
The fuel bowls need to be boost referenced to equalize the pressure in the carb. When all parts of the carb are referenced to boost, the atmosphere in the carb is as if it isn't boosted at all. Thats the goal as you need to keep the same kind of conditions as without boost for the carb to work right. Without boost referencing certain parts, you can force fuel back through the jets or possibly colapse parts of the carb.
The fuel bowls need to be boost referenced to equalize the pressure in the carb. When all parts of the carb are referenced to boost, the atmosphere in the carb is as if it isn't boosted at all. Thats the goal as you need to keep the same kind of conditions as without boost for the carb to work right. Without boost referencing certain parts, you can force fuel back through the jets or possibly colapse parts of the carb.
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