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Author Topic:   Question for KP (carb)
juliaferrell
Dirt Freak

Total posts: 370
posted April 13, 2004 01:54 PM  
I have a 4412 style carb set up for alky. I have to put what I think is alot of jet in this thing to get it to sound right and react. Upon throttling this thing its either wide open or not at all. Has no midrange throttle on the thing. It's all or nothing!!! I've tuned and tuned in this darn thing. Think its just too much enrichment circuit? It's on a 4 banger 2530 cc 14:1. I have a 350 style (keith dorton series) on gas that works great. Wish I could get the response out of the 500 I get with that. Any idea would be greatly appreciated. I didn't know you then or I would have been dealing with you!!!!

Thanks

KPLugnut
Dirt Forum Champ
Total posts: 1019
posted April 13, 2004 02:01 PM  
Strange application for an alky motor, but it's possible that you don't need the pump shot the carb is giving the motor, since it's a larger carb than the 4cyl motor needs.
You're probably drowning the thing with alky when the accelerator pump circuit activates.
Try changing it to a 30cc pump with about a .031"-.035" squirter (even tho it's on alky, yes), and a pink pump cam (#330).
This will in a nutshell cut back the over-abundant alky pump shot that is probably too much for that little motor.
Let me know if that doesn't work, there's other things we can do, too. The transition between idle and main circuit probably needs to be changed as well, but I can't say in detail because I'd need to see what has been done to the metering block, air bleeds, and boosters to know for sure.

Hope that helps,

KP

[This message has been edited by KPLugnut (edited April 13, 2004).]

juliaferrell
Dirt Freak

Total posts: 370
posted April 13, 2004 05:02 PM  
Without 99 jets or so you might as well not even have the carb on the engine. This thing lean popped and things like that. I put a flat plate over the carb and realized this thing needed more fuel. I noticed this because it reved nicer when I placed my hand about 2 inches over the carb. Then used my little flat plate and slid it across the top of the carb inlet. I started with 70 jets and 25 squirter. I kep jetting the thing upward and went past the 99 's I have in it now and above that didn't seem to help. This carb idles great and sounds responsive. ***This is an obstacle course racer*** It really revs nice. You can flutter the throttle forever and this engine doesn't flud. I've been fooling with carbs a long time and am pretty familiar with things. Could I send it to you and let you check it out? Just give me the info.

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juliaferrell
Dirt Freak

Total posts: 370
posted April 13, 2004 05:11 PM  
So your basically saying jet up and cut the pump back.



KPLugnut
Dirt Forum Champ
Total posts: 1019
posted April 13, 2004 05:36 PM  
It sounds like the carb was not properly built for alcohol use. 70 jets are for running on gas, not alcohol.
Keep in mind, alcohol needs to flow about twice the volume of fuel than gas.
With the "old" method of metering block modification, typically a .100" hole is drilled directly above or to the side of the jet hole, and jets in the 92-96 or so range are then used in a carb of that size venturi/baseplate.
If you are barely getting in the ballpark with 99 jets, that tells me you're trying to run a gas carb on alcohol. Am I right?
Feel free to send us the carb and we'll convert it properly to alcohol and it will feed the motor the way it should.
Contact me thru email here if interested:
kineticperformance@thedirtforum.com

We can talk pricing there.
Of if you're sure you want us to work it over, send it to the shop address on our website (click on the banner link off these forums).


Dayton Umholtz, co-owner
Kinetic Performance

juliaferrell
Dirt Freak

Total posts: 370
posted April 14, 2004 02:32 PM  
This is an alcohol carb. I sent you email.

thanks

    

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