Hey guys...sorry to be asking so many questions lately.

Have been thinking about getting a demon JR (525) to replace my 500 edelbrock for quite a while.  More tunable, and consensus here seems to be that this is a really good, smooth carb, and a good fit for this engine...

Most stuff I find says the road demon jr is good for a cam up to 210 degrees.  My cam is 224 duration, but looking through old posts here, seems like some are running that carb with cams over the 210 degrees... true?  Any thoughts as to how hard & fast that cam duration rule is on the demon jr?

Jegs had reman-ed 525 jrs for a pretty good price right now, but trying to figure out if it will work for me....any thoughts/experiences?

Thanks!
Ron.

Ron Grove

Wauconda, IL

I have the Isky E4 in my 272 with the Demon Jr. 525 and I'm very happy with it.  Idles good and is a strong runner.  The Isky E4 is 216° @ 0.050” with a 108° lobe centerline but does like the valve lash opened up to the loose side rather than tight.

 

I see no problems with a 224° camshaft with this same carburetor on a larger sized engine based on what I’m seeing on my current combination.  But I’m not far from actually testing the Demon 525 carb on a +060 over 312 with a 238° @ 0.050” camshaft.  When the 3X2 testing is complete, the next series of testing is single four barrel intake and carb testing which will include the Demon 525 carb.

Lorena, Texas (South of Waco)

I'm in a similar situation/quandary to Ron and am now really looking forward to Ted's results. In a broader question though, can someone explain the significance of cam duration to carb size (sorry, I'm a real novice here) ? I've seen a graph with a 'compensation factor' curve to help factor a cam into the CFM requirement but I believe that the CI x RPM/VE equation is not well regarded by many anyway.

Cheers

Richard

Chelmsford. UK

Ted,

Thanks very much for the reply.  I was hoping to hear from you on this topic, as I remembered you had one.
Any idea how long until you can do the dyno tests?

I know stock is limited on the reman carb, and jegs has a generous return policy..maybe ill pick one up and wait to hear your results!

Thanks!!

Ron Grove

Wauconda, IL

If you get into the BG spec's for the Road Demon Jr carbs - you will find that the 525 and 625 is virtually identical - except for the venturi boosters. They basically have "throttled back" the carbs from the larger CFM rating by "choking" them with the booster arrangement.

There is a fellow on ebay that sells the very same "remanufactured" BG carbs considerably cheaper than the major suppliers. I got my electric choke 525 jr. for about $270 - which included the shipping.

Ted's comments about the cam / displacement relationship and what is "too big" is right on......too big for a 272 is going to be different than for an overbored 312.  

 
 Steve Metzger       Tucson, Arizona

Yup...on ebay for about $270 reman (thats plus shipping, though).  Its actually the Jegs storefront; same price as their website.  Ebay listing indicates they have 4...err...make that 3 left!

Ron Grove

Wauconda, IL