What are the advantages of each

 

I think mostly it comes back to personal prefrence.

I haven't really read much on a holley, but magazines seem to like demons a little more if they're going to do a forced induction motor. The mighty demons have adjustable air bleeds which give them more settings to mess with. But I've seen holley's with screw in bleeds too.

I think the bowl on the demons are a little better machined for better flow.

 

demons are like holleys that have alot of the holley tricks you can put on them... its like a factory upgraded carb.

still the same basic design as holleys, but with a few diffrent features.. if thoes features are useful to you or not depends on alot though.

 

BG came out with the line because they thought Holley was getting sloppy and resting on their reputation. It was probably true.

Since then, we've seen Holley respond. Compare a Holley HP, Proform mainbody, and Race Demon - they look almost identical (except for the Demon bowls, of course).

I think Demon puts more into their products for the same money vs. Holley. I still think Holley's are kind of ugly, but if you go for that "function over form" thing, you get over it.

A couple of years ago, a local guy here wrote an article about his experience with Demons vs. Holleys. He's been tuning and racing Holleys for over 20 years, and was saying things like 20-40 dyno HP improvement, G-Tech 40 HP equivilent improvement, he'll only recommend Demons from now on, etc. Looking over the write-up again, I see he's only talking about vacuum secondary carbs. So, I'll take that all with a grain of salt.

Except for lack of a choke, I couldn't be happier with my Holley/Proform. But, it's not on a daily (nor even regular, for that matter) street driver.

 

I purchased a 625 road demon to try replacing my 750 holley with. It certainly looked like it would perform better, smoother radius turns where air would flow, the choke tower was slightly shorter which looked like it would help airflow with my drop-base cleaner setup, etc. But I could not for the life of me get the 4 corner idle mixture setup properly, tuned for a damn hour on the thing with my vacuum gauge and could not get it idling as smooth as the 750 Holley. I figured it would be harder to set but yield a more accurate idle mixture once I got it right. No dice at all, don't know if I'm just stupid or what...

Then I ran into problems with a shim/guide piece of plastic for the choke push rod mechanism that was screwed up/binding right out of the box which caused the choke to bind and hangup all the time. The choke push rod or whatever it's called was made of the weakest crap metal I've ever seen too, so it got all bent out of shape, causing even more binding problems. I could almost bend it by breathing on it. Anyway, I got fed up and returned the bastard like 2 days after I got it, choke garbage was pissing me off, I didn't pay 300 bux to have it screwed right outta the box. Still have my 3310 750 Holley, runs great, whos to say if I would have been happier with the road demon after a little more time though (and without a screwed choke mechanism...)

 

Anyone can compare the demons to Holley street avenger for best power AND drivability?

 

i think that i should point out the results that my holley street avenger netted...

when i engine dynoed my motor, we initially used the shop carb (a holley 800 carb with 800$ is work done to it) to dyno the motor.

the a/f was perfect side to side, and the motor ran great with it.

The engine guy was even surprised at how the 670 only made a few less hp than the 800 with the work done... i want to say it made 10ftlbs less and 8hp less...

the a/f on my holley was off by 1 point side to side,i think the left side was one full point leaner. this is typical of most carbs... most aren't very good in this department stock according to what he has seen thus far (he's dynoed probably a couple hundred carbs)

Anyways, its basically almost enough to justify cross jetting... which i might do for when i start running nitrous. Aside fromthat it made good power, and the a.f is great through the rpm range at wot. the metering system is very good on mine. Part throttle is pretty good too, altho i seem to be having issues with the vac sec. opening a little soon, even with a heavier spring in place... partly the reason for my bad 60's...

Over all, its a toss up, i asked about upgrading to a demon, and the engine guy said your just as likely to get a bleh one.

Steve

 

To solve the VS opening issue, get the Quick Fuel adjustable secondary housing (I know Jegs carries them, Summit might as well). It has a needle valve that you adjust to control the vacuum signal, which is really what you want to do (the spring not only controls when the secondaries open, but at what RPM they are fully open). Since the concept of the VS is to allow the fuel to get through the metering passages before the butterflys open too much (as in, bog if they open too much before fuel gets flowing), all you want to do is provide a gradual initial opening of the secondaries - after that, you want them to open up as quickly as possible.

Also, the reason I'm discounting the local guy's raves about the Demons is it was all in the VS opening that produced the improvement. If he had compared Holley DP to same size Demon DP, he probably wouldn't have seen much, if any, difference.

Having said all that...

You want to improve your 60' times? Ditch the VS and get a DP. The peak torqe/HP difference between the same size VS and DP carb will be minimal if any at all (Jester says maybe 10 better with the DP), but the big difference is "area under the curve". The DP will get going better from lower RPMs every time, and that's what improves 60' and 1/4 mile times.

 

Personally, I don't know anyone with a Road Demon. From the literature I've seen, I wouldn't go with one. The Speed Demon is clearly the superior carb, and if you're concerned about the higher price, you're looking in the wrong place, anyway.

Besides, the RD's are all VS - yuck!

 

yeah cant say that my next carb wont be a mech secondary carb lol.. only reason it is right now is for fuel milage, but now that it isnt an issue much, unless i go efi soon, im stuck with it.

 

Oh yeah another difference is that you will have to modifiy the kickdown bracket if you're trying to hook a 700-r4 up to a Demon. I finally got around to ordering it and test fit it against my 750 dp. Not much of a big deal looks like if I just cut the notch off a little bit it will bolt right up.

 

Same story with a Holley or Edelbrock.

 

you can get adjustible brackets that will make it a bolt up... same with holley and edelbrock.

 

I was talking about the Holley Bracket they sale. I figured it was a direct bolt on for their carbs?

 

For Holley, or Demon?

I was thinking more of the cable hook-up to the throttle shaft geometry. It isn't the same for a throttle valve cable (what the TH700-R4 has) as it is for a kickdown cable.

 

I took pliers to it and bent the tab flat but then everytime I'd crack the throttle the bracket would move over. My fix was: In the back of my RPM intake, right below the throttle bracket, is a threaded bolt hole. I notched the back of the bracket and then put a long bolt through it into the intake.

As for the Demon vs Holley debate... The main reason some people who buy Demons and hate them is because they assume its just a fancy Holley. ITS NOT. Even though it looks like one and shares the same parts, the way you tune it is very different. As for which one is better who knows. Both can get you goin' pretty good. Just remember, don't ever think of a Demon as a Holley or else you'll never tune it right.

 

Hmm... wonder what I'm gonna do with mine since it's a victor jr with a spacer. Which way did the bracket pull in towards the carb or away from it?

 

Away from the carb ....This is probably more a result of my TPI throttle cable though ...its too long and is constantly wanting to move over.

 

Ahh I figured you had to go to carb 3rd gen cable. I was planning on buying a carb TV cable.

I probably could just drill a hole in the bracket and put a bolt with nut on the side so if goes to pull the nut will hit the carb flange and stop it.