I started looking hard at my Quick Fuel 950 carb as to why I can't get it to idle under 1800 rpm. This carb has been modified for a blow through application and I'm trying to make it work on a naturally aspirated motor. I installed all the factory air bleeds, jets and the power valve with no luck. After reading several posts I decided to take a closer look at the throttle body and idle slots. I found a slit/cut made in the idle slots of the primaries. I'm thinking this is my problem. Is this a normal modification for a blow through set up?
http://<a href="http://s263.photobucket.com/albums/ii154/lundgren_marc/?action=view&current=0919091232c.jpg" target="_blank"><img src="http://i263.photobucket.com/albums/ii154/lundgren_marc/0919091232c.jpg" border="0" alt="slot"></a>

I'm having a problem posting a picture.

i don't know, man...i just don't know.

Never heard that man as to why someone would cut more slits. I guess it makes sense for a blower application because you are adding pressure above atomosphere so you have to account to add extra fuel some how.

If thats the case I really see it hard to make it work depending on how big the slits. You can try to adjust the blades down as low as possible on them making very little noticeable and try putting smaller jets in ti.

I would personally replace it and save it if you blow it some day.

Like to see a pic though.

Marc...

Try to call the co. who modified the carb, if you know who did, otherwise call This place!

CSU Carbs at (909) 851-6955
E-mail: info@csucarbs.com


They may help you ! They do blow thru...

Yesterday I got a hold of the shop that did the work. They said that they sometimes do make cuts like what my carb has, but they don't keep records as far back as when they did mine (3 years ago). They did say it would make my motor run rich and I was fouling the plugs really bad. I got a different 950 on the motor now and it's not fouling the plugs. I will put new plugs in later today, the current ones have been cleaned a couple of times. As for the carb, I think I will get a new throttle body this fall/winter and try the carb again.

Did they say what else they might have changed in the carb? Do you know the stock sizes for all the holes in the carb (air bleeds, emulsion holes, IFR, PVCR)? The whole fuel curve could be all wrong for a normally aspirated motor. It might be safer to look for another carb.

[QUOTE=camaro man;1294263]Yesterday I got a hold of the shop that did the work. They said that they sometimes do make cuts like what my carb has, but they don't keep records as far back as when they did mine (3 years ago). They did say it would make my motor run rich and I was fouling the plugs really bad. I got a different 950 on the motor now and it's not fouling the plugs. I will put new plugs in later today, the current ones have been cleaned a couple of times. As for the carb, I think I will get a new throttle body this fall/winter and try the carb again.[/QUOTE

Throttle body is typically a term used with efi setups.Are you referring to the carbs base plate that houses the throttle plates or the carbs main body above it?Regardless,mods could have been made to the metering blocks as well as the main body and baseplate.
I would return the blow thru carb back to its original settings and sell it with a disclaimer that fine tuning for your application may or will be reqd.

I would sell the carb as a blow thru to someone going that route rather than try to retro fit it back to N/A. Take the cash and put it towards a new carb. JMHO.

I kind of agree with Greg on this one.Another thing to think about,do the throttle plates have holes drilled in them?

I think I will sell the carb as a blow through with the disclaimer.

Can't speak for the QF stuff but I can tell you on our blow-through stuff we have a lot of extra channels cut into the bottom of the base plate so that the boost will pressurize the end of the throttle shafts so the fuel does not blow out under boost. The calibration is also completely different in the a blow-through cannot be ran on a n.a. engine without major changes. The needle and seats are larger , the power valves are high flow and the pvcr are a lot bigger. Air bleed and jet circuitry is different. You may contact them and see if you can change the other things mentioned and modify it for adjustable pvcr's and make it work as I have converted a few of ours in the past to do this.