Demon VS Holley
 

Just decided to upgrade from my holley DP 650 to a demon DP 750 decided i needed some more fuel, felt like i was running out of fuel on the top end, just curious what im to expect before it gets here, i've heard lots of GREAT things about demons, anyone had any problems with them?

Re: Demon VS Holley
 

Just be warned.. in the past every demon vs holly vs post has gotten ugly. Folks have some stroooong beliefs :)

Re: Demon VS Holley
 

try jetting it out more?

Re: Demon VS Holley
 

Going to a larger cfm carb has nothing to do with the amount of fuel an engine gets. A demon is nothing but a glorified holley. I have never seen one that actually runs right. If i were you I would send the demon back and tune the holley you have. Its likely going up a couple jet sizes in the back will fix your issue on the top end. Theres a bunch of things that could be causing your problem. Throwing a bigger carb at it probably isnt going to help much. It might mask your problem but low end performance will suffer from the carb being too big for the application.

Re: Demon VS Holley
 

I just seen its a 350 your working with. A 750 is too big. The 650 you have should be more then enough jetted out just right
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Re: Demon VS Holley
 

Demon..Holley to each their own.There designed to do the same thing. I have a 625 vacuum secondary Demon on my 350 with no complaints. I to would suggest you try changing the jets before you swapped carbs.

Re: Demon VS Holley
 

You asked !

I couldn't agree more with cableguy, There's one of those pos on my 502 (as I bought it) and soon as funds are available it's GONE. I've had nothing but problems even after replacing every single component in my fuel system and a by the manual (from Berry Grant) rebuild, They just like puking gas out all over for no reason.

Every single vehicle I've seen at shows with a Demon had fuel stains all over the aluminum intakes, I can't repeat here what they said when I asked about it. ;)

My advice; When you get it don't even open the box, Ship it right back for a refund.....:smoke:

Re: Demon VS Holley
 

I have a Holley on my truck, was there when I bought it. Needs a rebuild but it still does what I need it too. I have to agree Id just re-jet your Holley, Jets are cheaper than a new Demon anyway IMHO.

Re: Demon VS Holley
 

Before buying a new Demon.... BG has shut it's doors which might make finding parts or getting warranty issues handled a PITA.

Re: Demon VS Holley
 

I would stick with the Holley.

Re: Demon VS Holley
 

That another very valid point as of feb 18th 2011 barry grant is out of business closed there doors. I guess there reputation finally caught up

Re: Demon VS Holley
 

didn't barry grant used to work for holley? i thought he did. a bigger carb won't fix your trouble. it could even be as simple as your float not allowing the bowls to fill up properly. sounds like you need to tune your carb to fit your application.

Re: Demon VS Holley
 

Yes barry grant worked for holley years ago. The demons are basically just a billet holley with a few changes. If you want an upgrade A quickfuel or proform as well as one of the new holley ultra series are also great carbs.

Re: Demon VS Holley
 

ive known people that run quickfuels and wish they had never spent the cash, as far as affecting my low end all my power is on the top end hence the 3500 stall, the race shop in town highly recommended a demon and i got a great deal on this one, as for it being to big....possibly but every highly modified 350 i have seen runs a 750, as far as fuel stains on my intake yea already there with my holley cant get much worse. i really hope your wrong cuz i wont be able to get a refund lol

Re: Demon VS Holley
 

I guess at this point all I can say is good luck.

Re: Demon VS Holley
 

Ha ! It's not the stains, It's what causes them....Sitting at traffic lights and have the damn thing randomly sit there and flood out stalling the engine, leaving you stuck in the middle of the roadway.

Did I mention all new fuel tank/steel lines to the front/braided lines under hood/fuel pump/return regulator with line to the back/2 yes 2 fuel filters and 3 float valve sets all adjusted below spec and pressure adjusted below spec....

As cableguy said, Good Luck !

Re: Demon VS Holley
 

ok ok so i hear all these problems with demons, can anyone tell me what causes these problems?? and why they are so terrible if they are a just a Glorified Holley?

Re: Demon VS Holley
 

Way to big of a carb, too little cubes, stock heads aren't helping. Rejet your 650. You'll windup having to rejet the 750 way down.

Thats way too much carb for a 340-350hp motor.

Re: Demon VS Holley
 

340-350 hp??? try closer to 450 hp

Re: Demon VS Holley
 

350 .60 over iron eagle h-beam rods, sealed power high comp pistons, forged crank, vortec heads, edelbrock performer rpm vortec intake, roller rockers, .488 .510 cam 11.5-12:1 Compression

Re: Demon VS Holley
 

:rolleyes:you cant believe everything the guy at the parts counter at your local speed shop tells you......

I too have never seen a demon that worked "right". I have had numerous problems with holleys too...so I guess I cant say much good about either one..lol

Re: Demon VS Holley
 

Big cam, high compression, stock heads......450 is a pretty bold claim

Re: Demon VS Holley
 

how worked over are the heads? Some better flowing heads may be the reason why your lacking top end. Vortecs are good for a stockish motor, but id start looking at pro 1's or afr's.

Re: Demon VS Holley
 

Tell me more about your Pistons Are they Dome, or Flat top, what cc ?
Tell me more about your Cam ? What cam, Duration at .50, Lsa ?

I had a Dyno'd 383 430 HP with Flat tops, Comp XE284 Cam, Air gap, Dart Pro 1 Heads,
and a Demon 750 DP... I loved that Carb...

I have to say I agree with the 375-400 HP range

My Heads flowed more than Stock Vortecs, and it was a 383, that was tuned very well.

Re: Demon VS Holley
 

Not much just a little porting and polishing i thought about heads but they come at a very heafty price for the Performer Rpm Heads that i need to match my current setup but that could be the problem.
Stock Vortec Heads flow just as good if not better than the stock double hump camel back 2.02 heads-proven fact.
My whole set up is edelbrock top end kit minus the heads thats why the professional builder claimed 450 horse not the 500+ edelbrock advertises.
I've had my fair share of Holleys also and have had just as many problems thats why i decided to give something else a shot since i have heard alot of good about them. Not intending to offend anyone by asking about them.