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.

Re: Demon VS Holley
 

Well, the original reason i was going to suggest against bg's was because numerous reports of people opening up a new carb to find shavings throughout the casting, as if it was never properly cleaned before assembly. Plus, the guys above informing me they are out of business now. The four corner idle ive heard from alot of guys was a neat feature, and my cousin runs a750 one on his 383 malibu and likes it. Same animal different name, like comparing GMC to Chevrolet.










(quiet down you four eyes, haha!)

Re: Demon VS Holley
 

234 244 duration on the cam, the pistions are flat top single eyebrow style i dont remember the CC of them i got the bottom end already assembled for a good deal since the block we build spun number 2 rod bearing the first build and rod bearing 4 on the second build (couldnt ever figure out why) weird since it was a running engine when we tore it down personally i think it was something with the machining but the machine shop denied it and said everything met specs both times

Re: Demon VS Holley
 

check out aed performance .com out of Richmond Va. Every gearhead in the world said my my 650 holley was more than enough for my warmed up 400 .
Put one of their( rebuilt Holleys on750 cfm > truck has never run better . I recommend you read their article . This is their main business with lots of experience with matching carbs to what you got as far as heads , cam specs , compression etc. Summitt Has just started selling some of their carbs --Ithink > maybe Jegs ?

Re: Demon VS Holley
 

Maybe i got fed a little bit of BS about the horsepower??? I havent had it on the dyno yet waiting for the weather to warm up a bit

Re: Demon VS Holley
 

I build hot rods for a living. We dyno every engine. Prior to now I ran a speed shop and we had a full service machine shop. We built engines everything from bone stock to 900hp naturally aspirated small blocks. I would bet money that on a legit dyno your engine is making no more than 375hp. Vortecs just dont flow on the top end and your cam is too big for vortecs in the first place. Most people who try to port vortec heads do more harm than good. Dont take me wrong Im not jumping on you on dogging your engine etc. Im just throwing out some real world experience and legit advice. A 350hp small block runs like a scalded dog. Just dont expect vortec heads to pull like a freight train past 5500rpm. They run out of flow capabilities. Yes I will say on paper that a 750 is too big but in the real world its likely the best choice. I however wouldnt have paid the extra dough for a demon. All you gotta do is go to the local drag strip. You wont find many edelbrocks or demons on serious cars. IM not saying holleys are perfect. Nothing is perfect. Any carb will require some tweaking. Most of the time the problem lies with the guy trying to do the tweaking regardless of the brand of the carb. I know some pretty serious engine builders that refuse to even touch a demon. Im talking guys that participate in the engine builders challenges etc etc.

Re: Demon VS Holley
 

Sounds like you have a nice combo there really... and I don't want to sound like I'm bashing cuz I'm not, just being realistic... Flat tops in a 350 will give you a 10.3 Compression ratio, with a 64cc head. the Vortecs flow about 220 CFM which is worth about 450 HP Max...
Take a look at this article, it is almost identical to your Combo, they also test a Holley versus a Demon...
By the way, the Shavings was a problem a long time ago, and they did clean up their act. the Demon I had was Awesome, hardly had to do any tweaking to get it running really clean... I just sold a Holley 750 DP that I couldn't get to run cleanly with My Current Combo and I ended up Buying a Pro-systems 850 CFM...

Re: Demon VS Holley
 

sounds like i need to invest in some decent heads....
i had intended on getting a set a little while after my build, but got stuck with the Vortecs only cuz i ran outta money after building two other engines (not a happy wife) lol
i hope this demon isnt as bad as i hear but aside from finding metal shavings i havent heard why they are so bad? this carb has been ran and tuned before
(not to my application) but he said it was a good carb and just needed to sell it for a blow through carb

Re: Demon VS Holley
 

thank you jrcaprai......where is this article your speaking of

Re: Demon VS Holley
 

Some decent heads will put you where you want to be. I'm not trying to bash you, just trying to lower your expectations so you aren't let down on the Dyno.

Re: Demon VS Holley
 

Check out these heads. they are cheaper than AFR's and flow just as much with an as Cast port... your engine would really wake up with the 195cc Profilers, and Chad Speier is Awesome to work with. I have the 210cc version on my 408
http://www.speierracingheads.com/profilerecono.htm


Sorry I forgot to post the Article Duh! I'm from Boise by the way, it's good to see a fellow Idahoan online

http://www.chevyhiperformance.com/te...est/index.html

Re: Demon VS Holley
 

Can you say can of worms....
Quickfuels: look cool but they are hit or miss tuning wise like the old hollys
Demons: Improved holley but very picky on float level but very reliable when set and not as touchy on weather changes.

750 Is too large for a mild 350
I run a 650 speed demon on my 361 sbc
Too each its own though. Ive run several different sizes and combos on my motor and by far the demon has had the best results. I bought this thing off a shop floor covered in dirt blew it off cleaned it up and bolted it on and ran better than anything Id had on there prior.

Re: Demon VS Holley
 

so i need to be looking for some 64cc 2.08 heads from what im gathering?

Re: Demon VS Holley
 

You'd do better with a 2.05 Valve, and yeah stick with the 64cc chamber, which will keep it at 10.3 Compression, just right for pump gas

Re: Demon VS Holley
 

The afr 195's or Brodix ik series of heads are an excellent choice. Yes they are pricey but you get what you pay for. Nobody is bashing. Just throwing out some experience. Dont take it personal. The dyno breaks hearts everyday.

Re: Demon VS Holley
 

lol i can take a little bashing thanks for the advice fellas, ill be letting everyone know how my demon turns out im gonna at least give her a shot.