Demon...Buy one get one free.

Ashley · Post by **Ashley** » Sat Dec 02, 06 8:33 am

Well i have a Demon on my motor (supplied by Neil) which was stripped and checked by Neil.
When i first ran the motor with it on, it was abit of a pain to set it up, but once i got me head round it, everthing was Cosmic.
I have always in the past run vac sec carbs, After fitting this Demon, i would never go back to a vac sec again

Also this year driving to the Nats, we used £20 less in fuel over the vac sec the year before

Not that i'm bovvvered.
As for the build standards, i know its been said before, but we are talking American parts here

if you wont quality parts you buy a German car

Thats my opinion.

Dave-R · Post by **Dave-R** » Sat Dec 02, 06 9:05 am

Sorry Adam and Neil. I was VERY tired last night and out of line.

I have had a realisation though.

Neil is following Don's lessons on tuning Demon carbs and is assuming all engines/carbs must be tuned the same way. Thie demon is why the distributor needs a lot of timing taken out of it to get a high initial.

I am experienced in tuning Holleys and Carters. We are talking 25 years here and 5 years before that I was tuning Fords with various carbs.

My mistake is I am assuming you tune a Demon the same way.

So I think myself and Neil are both wrong and need our heads banged together.

Anonymous · Post by **Anonymous** » Sat Dec 02, 06 9:32 am

First off lets please quit the damn insults here, it serves NO purpose at all

I knew where this thread would end up right at the beginning, this is one thing that really

me off with this board, it's always one opinion and nothing else.

That said...., Dave as you know I agree with Don, I PASSED my motor vehicle apprenticeship nearly 30 years ago, then HGV, then Heavy Plant, I have been a mechanic my whole working life, not someone playing at it but doing it for a living.

I can read and have an enquiring open mind, I have Don's tuning guide and have read, read, read over and over, it's bang on the money, the proof of that is the sheer amount of customer referals, BG actually send their customers to Don for tuning advice.

Don has been doing this for over 40 years, a lot of that time for a living, don't you think if he was wrong he would have gone bust by now?

And to put the record straight anyone with a set of basic hand tools and a timing light would be able to get a demon dialled in within 1/2 an hour, the only issue is the distributor recurve which BTW 99% of motors with demons need.

If you struggle with them Dave then that ought to tell you you're approaching the problem from the wrong direction

I have an idea on what rattled your cage Dave..... take a look at my post at 9.07 last night, Adam posted a laugh at 9.09, this was not a response to my post as no one could have read it and then posted within 2 minutes

Like I said at the top.... quit the insults as i'm certainly sick of it

Anonymous · Post by **Anonymous** » Sat Dec 02, 06 9:44 am

Dave

I thought we'd come to the point where we know I don't talk about Holleys

You will never see my name on a Holley thread mate cos I don't know what i'm talking about for one.

so lets get back to the discussion

DEMON always ignition first, then carb

HOLLEY dunno... ask Dave

and Dave if there's anything offensive in my last post then I apologize in advance

Anonymous · Post by **Anonymous** » Sat Dec 02, 06 10:20 am

I do not wish to get involved in this argument but I feel very sad that what for me was a very interesting thread deteriorated so quickly.
I am relatively new to the world of Mopar and American cars and I was very pleased when I found what I thought was a great group of like minded individuals that I could turn to to get me through the difficult times I was bound to have when working my 37 year old car. I too am not a mechanic and because I don't know much about the technical stuff and cannot afford to pay garage prices I was in two minds about buying an American car, but when I found your site I decided that with my enthusiasm and your combined knowledge I would jump in with both feet. Unfortunately this will mean me posting many stupid questions which have probably been asked before or may be considered basic by some but if you don't know you don't know!. This type of thread will make me, and others I am sure, think twice about posting a question or offering any opinion just in case it is laughed at or considered stupid by some.
Please lets keep the doors open to everyone, there are more of us out here that don't know and we look to those of you who do to help.

Martin

Alex · Post by **Alex** » Sat Dec 02, 06 10:47 am

I too am upset by this post, once again it is proved that we can't all play nice.

This board will answer any and all questions have no fear about that 69er, and this one will stay as if you look really really hard there are some handy bits.

but I wish y'all would think before you post, if you have a gripe use the PM, I have spotted not too subtle threats in this thread, that will not be allowed, any more and action will be taken full stop.

sometimes it's like looking after kids at playime on here.

MilesnMiles · Post by **MilesnMiles** » Sat Dec 02, 06 11:25 am

69er, don't be put off mate. Both Dave and Will have given me really helpful info over the past few years along with many other members.

MilesnMiles · Post by **MilesnMiles** » Sat Dec 02, 06 11:27 am

Adam, just read you're a heating engineer. Please see my thread in 'General'. help.
Apologies for thread hijack, but it probably needed it

Anonymous · Post by **Anonymous** » Sat Dec 02, 06 11:48 am

69, don't be afraid to ask anything here, you will find answers here to everything, problems do arise when there's more than one solution or opinion

As for Dave and myself well we argue like cat and dog especially on this subject, par for the course and i'm sure everyone is used to it by now, probably the highlight thread for the time being

No harm is done and it never goes toooooo far really, we are adults and the playground can and does get a little rough, it's all in the process of a good debate/arguement (delete as appropriate)

Alex, I didn't notice any threats, am I on the right thread??

MrNorm · Post by **MrNorm** » Sat Dec 02, 06 1:35 pm

Neil, I had always mistakenly ASSumed that the Demon was basically a Holley with updated knobs on that grew out of BG initially making parts to update Holleys. So it added the four corner idle, and more recently the idle-ese etc, flowed better, sight plugs, prob had more efficient boosting on the venturis etc. So I would have assumed that the tuning principles were pretty much the same as with Holley.
My intent had been to most likely go with a Demon (even before you appeared!), though I'll consider other options like the updated Holleys (Avenger?) or even proforms or AED etc. (secretly I'd like to try a Thermoquad but forget that for now

)

Anyway, I'm curious as to what it is about the Demons design that require the different tuning approach, and why they like a lot more initial timing etc than a Holley design. Or is it a combination of subtleties? A genuine question, just interested to find out more.

Dave-R · Post by **Dave-R** » Sat Dec 02, 06 2:18 pm

Wil wrote:the only issue is the distributor recurve which BTW 99% of motors with demons need.

If you struggle with them Dave then that ought to tell you you're approaching the problem from the wrong direction

Exactly. That is what I said this morning. I don't understand why you don't read what I write?

Neil I have talked about Holley and Carter tuning and you have chipped in with this high initial timing thing before. No reference to it only being a demon thing has ever been mentioned by yourself and I am not convinced you realised that. You have called me a "butcher" in the past for drilling Holley throttle blades even though that is what Holley do themselves.

Now I see that it is only the Demon that needs the settings you suggest. I have already apoligised for the misunderstanding. I have not called you any names Neil. I did call Adam yes. But not you.

But you can't blame me for the misunderstanding. You never said these carbs do not work right out of the box.
You never said they needed stripping down and rebuilt/repaired before fitting.
You never said you need to modify your distributor to get the carb to work.

We even argued over carb sizing in the past. You failed to mention that a 750 demon actually equates to more like a 850 Holley yet you slammed me down for suggesting a 850 Holley was a good size for a hot 440.
750 was as big as a 440 needs you said. But that was because you didn't know the difference.

The Demon at normal timing settings seems to be VERY rich. Maybe oversized fuel feeds to the idle circuits maybe?
I have never seen any reference from yourself that if you fit a Demon carb you have to modify your distributor to limit the total mechanical timing advance to around 15 degrees (most mopar dizzys have around 25 degrees in them).

I am sure this is not just news to me. Gavin seems not to have realised and there is not many on here that are as clued up as him.

And yes I know you were a HGV/plant fitter for many years. But how many American V8s have you tuned in that time? Many of my old mates are or have been professional mechanics over the years. I used to tune THEIR cars.

So I promise never to say ANYTHING in any post about Demon carbs. They are your babies.

Cannonball · Post by **Cannonball** » Sat Dec 02, 06 2:25 pm

love the banter lads
BUT dont go gettin upset at it, its to easy to see your arse on a computer when things are bein said and you cant sort it face to face, believe me i have wanted to shove my computer up plenty o guys arses in the past
it aint worth gettin wound up about, have a great day like this handsome guy did at the nats...............

Dave-R · Post by **Dave-R** » Sat Dec 02, 06 2:27 pm

yeah and my last post was STILL too OTT. Sorry Neil. We both need anger therapy.

latil · Post by **latil** » Sat Dec 02, 06 4:13 pm

A tune-off at the Nats. 2 identical cars,one of you with a Holley the other with the Demon. All the tools,best set up in the shortest time.

Anonymous · Post by **Anonymous** » Sat Dec 02, 06 4:17 pm

Gavin

Don does say in his tuning guide that higher initial timing figures are directly related to higher duration figures @050 and isn't carb specific

the higher the @050 figure the lower the effective cylinder pressure at low rpms especially, so with the lower cylinder pressure the fuel takes longer to burn, the flame front is slower so the plug has to be fired earlier to still achieve max rate of expansion at the 12*/15* atdc. Also lean mixtures like at idle, light throttle and slow speeds take longer to burn also, and yes you can have a lean idle and the stink from the pipes, this has nothing to do with the air/fuel ratio but the actual time the mixture has had to burn

Also if the plug is fired really too late then the exhaust valve can start to open before the fuel has completely burnt, it then carries on TRYING to burn in the headers, this will cause overheating, the stink from the pipes etc.

I can't comment on Holleys as i've not had the chance to check this out myself, what I need is a local car with a DP holley fitted and some time to take a look.

What I will say though is I do a fair amount of distributor recurves, mostly to do with overheating and the stink, these arrive here by post, I do them and send them back, I never see the carb fitted and unless the carb is a total mismatch to the motor then it is is not important.
Every single customer has called me a few days after getting the distributor to tell me overheating solved

But for the sake of an easy peaceful life this only applies to Demons

As for the Demon question

The airhorn is a much better design allowing more airflow, the airbleeds are better, most of the carb is billet and not cast so porousity isn't an issue, what is cast is done by a differnt method anyway, a demon weighs in at 14lb, a holley is about 9lb, and an edelbrock about 6lb, holleys and edelbrock castings are sealed by the plating method or that coloured coating, in fact there is a company in the states that takes porous holleys and replates them for resale.
Demons don't heat crack also