peglegpig

so, i've been shopping for a holly 600 cfm. does it matter if it's a manuel or electric choke?



also i remember seeing a setup on ebay a few months ago which was a rb intake for the holly but the guy had a demon 575 cfm i believe.



looking at the demons i must say they look pretty nice.



they come in 525, 575, 625 cfm models.



any1 use one?



should i just buy a holly instead?

13BTNOS

I use the 600cfm holley carbs for GM's with the prefix p/n 1850. You can't just slap a carb on a rotary and expect it to work properly. The carbs I use are vaccum secondary and I convert them to mechanical. I use a Racing Beat intake and open the plenum up. I drop it down 1/2in and blend it all in and use a 1/2in spacer for N/A motors or for Nitrous motors I use a plate system. The power valve is blocked and the secondary metering plate is modified. This setup is meant for track cars, drag racing, you can use it for street use but there is a slight hesitation when it transitions into the secondaries. But for drag racing it is great the way I set the carb up it is meant to be wide open. The racing beat carbs are great carbs people don't want to fork out the money for them but hell you can't beat them. They allow your motor to run smoothly with no hesitation at all. Webers, Mikuni and Dellorto carbs are also good carbs it's all in your preference I'm a Holley person.

12arotaryboy23

Having a problem here....what do you do with the omp lines for these carbs though? I got the RB intake , which I guess I could drill for vacuum or a carb spacer plate, but v8s lose vacuum after the carb at higher rpms. Wouldn't this be the same problem? other than that, I have to run premix? what a pain... '85 12a btw... with a Holley.

Latin270

Nah, I think the RB carbs are over rated if you ask me. I'm going for a Demon carb next!

rootbeerdragon

count me in for demon

rxtasy3

i have a 1/16 NPT nipple threaded into the sight plug of the primary float bowl. get a vacuum "T" fitting in the shape of an "F", upside down at the OMP. the two lines become one, going to the NPT nipple in the float bowl.

84stock

My fancy new demon has given me nothing but problems, no support from the manufacturuer either. I suggest the Edelbrock thunder series. This is by the the most reliable carb I have.

Latin270

What size Demon? Is it on a RB HOLLEY INTAKE? I think 525cfm will work on an SP 12a

zeroecco

what 525 cfm?! On a sp 12a? no way. The stock nikki was closer to 300cfm and even a ida weber is at 480 cfm (which if your runnning a sp 12a needed to be reventried to 400 cfm. Or thats what i am told by my engine biulder unless you want to have severe drivablility problems at the low end) I just don't see how you can even run a sp 12a at 525 cfm, a bp 12a yea, even 1/2 bp 12a, but a sp 12a....

Latin270

Yea your right, but I've seen guys running Holley 600's and 650's on SP 12a's and they ran great. I'm going to try out my 525cfm on my large SP 12a just to see if its worth the effort and also to see if its as easy as some say to tune a Demon! I know from my experience that any Holley is very tricky to tune. Weber's are a cinch.