so, to continue from a post i made last week i just took off the 570 holley which i couldnt get dialed in and i bolted on a 650 semi-speadbore holley double pumper. i believe it to be a factory carb off something ford from the late 60's, cause it has ford kickdown linkage and then a vent tube coming out of the top of the primary bowl which is usually only found on OEM carbs (if anyone has any idea what coulda used this thing im all ears btw). its got like 54 jets in the front and 85's or somethin in the back....

so i put a rebuild kit in this thing, put it on the car, set floats, and let it warm up. i notice that i can dial the air/fuel screws all the way in and it stays running, though the rpms did rise slightly when in gear and backed out about 1/4 turn.

wtf does this indicate?

 

Could be leaking a bit of fuel into the intake, or the idle screws may not be seating all the way. Fuel pressure could possibly be too high.

I'm still telling you though, you need to jet the hell out of that 570 to make it work. I just jetted mine up AGAIN, to fix a throttle response issue when I put the RPM Air Gap on and it leaned out. I went from 59's to 61's and it went from having ok throttle response in gear while rolling, to having whiplash throttle response in gear while rolling, and pulling a lot harder. So I've gone from 54/65 out of the box to 61/67, and it may still need another jet change to get ideal. Those 54's in the primaries are just WAY too small for that carb on a performance app, and it seems to use larger air bleeds as well, so that doesn't help the lean condition.

 

the large air bleeds kick my ***, when we block them partially with paperclips it idles way down @ 500 rpm in gear with no problem. im tempted to jb weld them closed and then use those super tiny bits (which i dont have) to make the holes smaller

 

heh i just stuffed in 67's in the front of my 600 and 73's in the back and that thing runs like a scalded dog. way better than when it had the wimpy 62's in it.

650 spread, i got one of those in the garage. though that one came off a 350 chevy used in a boat. had 62's in the front and 85's in the back.. ridiculous :|

 

Just jet it up. The jets and air bleeds work together. The jets let fuel into the emulsion circuit and the air bleeds let air into the emulsion circuit. Like I said, I had to jet mine to 61/67 to get the mixture right.

 

i was under the impression the jets do nothing @ idle

sailk, is this the kinda spreadbore you had? its like a half hybrid that i think sould be pretty cool if i could get it tuned right - although my 570 is new and i would really like to stick with it.

 

yeah that's pretty much the same one i got. it's a holley right? what's the #'s on it, cus i'll bet its the same exact thing i have. we only took the front and rear blocks off to use it in the rear to get rid of my metering plate on my 600. apparently those are supposed to be more fuel efficient or some garbage - i woulda used it on mine after a rebuild but holley told me to just jet up my 600. i dunno.

 

Jets do nothing at idle - when the lower butterfly is closed enough.

Did you guys check your power valve? You know the job of the power valve is to bypass the jets, right?