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Discussion Starter #1
okay fellas here is my questions

the motor i built for my uncles lp is doing great:D

it has a rpm air gap and a 1inch open spacer.
850 mighty demon{not my choice but does good nevertheless;)}

okay here is the problem.i ran it hard this evening.pulled plugs #1 is to rich-#2 is bout right all the rest are way to lean,almost scarey lean.

what should i do.if i jet it up well thats gonna hurt the #1 more and take #2 from bout right to worse.


????????????:)bulbshould i do away with open spacer,put 4 hole spacer or what,any help i will be thankful:)hand

demon carbs suck imo but im stuck with this one b/c he loves it,lol!!!!!:|err
 

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okay fellas here is my questions

the motor i built for my uncles lp is doing great:D

it has a rpm air gap and a 1inch open spacer.
850 mighty demon{not my choice but does good nevertheless;)}

okay here is the problem.i ran it hard this evening.pulled plugs #1 is to rich-#2 is bout right all the rest are way to lean,almost scarey lean.

what should i do.if i jet it up well thats gonna hurt the #1 more and take #2 from bout right to worse.


????????????:)bulbshould i do away with open spacer,put 4 hole spacer or what,any help i will be thankful:)hand

demon carbs suck imo but im stuck with this one b/c he loves it,lol!!!!!:|err
After reading the post, what kind of idle time before shut down and do you have a feul pressure gauge and pressure readings thru the day. M
 

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Discussion Starter #3
After reading the post, what kind of idle time before shut down and do you have a feul pressure gauge and pressure readings thru the day. M

5-6 psi with stock fuel pump idle time thru no wake zone back to the boat ramp,run the boat about 1 hour off and on 2 wot passes the rest of the time was cruising 3-4 grand.turned a a/b agressor impeller 5100 rpm max speed 65.2 in a taylor lp 21 foot heavy as hell boat,does that help:)bulb cutting impeller and adding some more timing to try and make it gain some speed and turn more rpms,but im afraid to do anything till i get the carb tuned in some more,:D
 

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Hotbro, Take the boat out with a plug socket and make a good pass. Slow down asap let cool alittle the pull the four corners of plugs on the motor,(or if you have time pull all the plugs and take a visual) It really is amazing how fast the color of a plug will change with 3 to 5 minutes idle time. Depending on mixture screw settings, manifold and timing. Might tell you another story. Lite tan plugs mean good feul to air ratio, If cyclinders come up up still black run a combustion check and see if things are close. Even is perfect 15% is acceptable. Good Luck M
 

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jetboataholic
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Here's your fix!

DuaneHTP told me to use this under mine. I haven't done it yet because I don't have the money, but my engine hasn't been run yet, so I can't tell you anything about them. But, Duane told me that this solved that problem on the dyno runs.

http://www.highvelocityheads.com/ss.htm

Duane is the guy to talk to about the Demons!
 

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E-7 Sheepdog (ret)
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Cantard
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Hotbro, Take the boat out with a plug socket and make a good pass. Slow down asap let cool alittle the pull the four corners of plugs on the motor,(or if you have time pull all the plugs and take a visual) It really is amazing how fast the color of a plug will change with 3 to 5 minutes idle time. Depending on mixture screw settings, manifold and timing. Might tell you another story. Lite tan plugs mean good feul to air ratio, If cyclinders come up up still black run a combustion check and see if things are close. Even is perfect 15% is acceptable. Good Luck M
x2
 

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Wishin I was at the lake!
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They call it "plug chop" for a reason!

If you want a reading for a particular condition, run it at that condition and shut it down asap (even coasting to a stop), then read plugs. Don't idle back to the ramp and then expect a good reading...
 

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Boat Nut
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DuaneHTP told me to use this under mine. I haven't done it yet because I don't have the money, but my engine hasn't been run yet, so I can't tell you anything about them. But, Duane told me that this solved that problem on the dyno runs.

http://www.highvelocityheads.com/ss.htm

Duane is the guy to talk to about the Demons!
Duane dislikes the Demon's, Super Suckers do help!


The problem lies with BG claiming their carbs are a much bigger CFM than the stated model. Like an 850 flows 900 plus CFM, too big of carb, results in loss of draw thru the veturies. This results in lean conditions with BG carbs.
 

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Discussion Starter #11
okay my question is 4-hole spacer gonna be better than the open spacer or just do away with the spacer all together;)

i know how to read plugs and to really get a good reading yes you are suppose to make a cruise run with no idle time or wot pass then kill.:)hand


by just lookin at a plug you think you may be reading it but in reality you need to look inside the thing towards th bottom of the electrode not just the outer part.:Danyway just trying to find a happy meduim:)sphss
 

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hotboat - what kind of intake ? I forget. Yeh, getting old and too many motors to keep track of.

And yes, the BG's typically flow way more when flowed dry. So, when going by same train of thought with standard Holley's, this can through you off.

Any pepper on the inside porcelian ?
 

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Is this the motor in question ?
"heres what i have a 9.1 781 heads 2.19-1.88 valves comp 294 solid,248-595 110-106 "

What cid ? What intake ? Does that stae you have 9.1:1 compression ?

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Sorry, your different threads and different motor builds have me confused on which engine you are talking about.

Can't follow and remember everything.

Thanks.
 

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Discussion Starter #14
Is this the motor in question ?
"heres what i have a 9.1 781 heads 2.19-1.88 valves comp 294 solid,248-595 110-106 "

What cid ? What intake ? Does that stae you have 9.1:1 compression ?

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Sorry, your different threads and different motor builds have me confused on which engine you are talking about.

Can't follow and remember everything.

Thanks.
my uncles mill,9.5-1 flat top .100 over bore bbc 475 c.i. closed chamber oval ports,2.19-1.88 valves.comp hyd roller.242-248-296-302-566-566,112-110.
performer rpm air gap-850 mighty demon.i put a 1 inch open spacer under it.

#1 is too rich for me-#2 about right light tan.all the rest to lean to me.little black around the begining of the threads,the porcelian look almost as white as they did coming out of the box.tried to look down inside as best as i can.but hard to see.notmuch if any color down inside on the porcelian.sorry spelling sucks.;)

wondering if it would help or hurt by doing away with the open spacer.:)bulb
 

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Can't comment on plugs without seeing them myself sooooooooooo..........

With that big of a carb and on a dual plane intake manifold, try it .

Removing the spacer will increase 'signal strength' to the boosters and thus they'll flow more fuel.

Furthermore with a dual plane,

A 'too small' of carb will pick up more air and less fuel with an open spacer.

Thus an open spacer helps these more than a 'big enough' or 'too big' of a carb.
 

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jetboataholic
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my uncles mill,9.5-1 flat top .100 over bore bbc 475 c.i. closed chamber oval ports,2.19-1.88 valves.comp hyd roller.242-248-296-302-566-566,112-110.
performer rpm air gap-850 mighty demon.i put a 1 inch open spacer under it.

#1 is too rich for me-#2 about right light tan.all the rest to lean to me.little black around the begining of the threads,the porcelian look almost as white as they did coming out of the box.tried to look down inside as best as i can.but hard to see.notmuch if any color down inside on the porcelian.sorry spelling sucks.;)

wondering if it would help or hurt by doing away with the open spacer.:)bulb
IMO I would do away with the open spacer and replace it with the 4 hole spacer. It is supposed to even out flow. I don't think that running it with no spacer would help anything, it would be just like dumping it into the open spacer IMO. But it's always worth a try before spending the money on the new spacer.

I wish I would have seen all these bad posts on the Demons before I bought mine. I would have stuck with what I know and went with the basic Holley 750 CFM. The guy that I bought my Demon off of was the one who turned me on to this forum. So it was a little too late, but I'm glad he did, I never would have figured out that there was something wrong with the Demons, or how to fix it.:D
 

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I don't think that running it with no spacer would help anything, it would be just like dumping it into the open spacer IMO.
Really...huh ?

The guy that I bought my Demon off of was the one who turned me on to this forum. So it was a little too late, but I'm glad he did, I never would have figured out that there was something wrong with the Demons, or how to fix it.:D
Thanks for the laugh ! That was funny ! LOL.
 

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jetboataholic
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Really...huh ?



Thanks for the laugh ! That was funny ! LOL.
That was just my non-expert opinion!:D

Also, I was typing that while you were typing yours. I didn't see your post until after I had submitted mine. Your explanation is 500 times better than mine, you're the expert here.:D

Thanks.:)hand
 

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Discussion Starter #19
thanks cfm,:Dim gonna take the spacer out and go from there,yeah i know its hard to read someone elses plugs over the net;)

i have had 3 demons in the past all of them sucked ass:|err1 was a 850 speed demon that came on my boat,boy what a joke other than the mill being blowed up when i got it 4 years ago,i never could get that thing to run right,and the carb was new,come to find out my cam duration was to big and i needed to upgrade,i did sold it to someone i didnt like and bought a holley;)the other was on a 406 roller in a pro-street truck we have that thing run great wot,idle loaded up mid throttle sucked blubbery.i called b.g. tech till they wouldnt even talk to me anymore tried every thing under the sun on that damn thing,it was a 825 race demon:)stit sucked,bought a holley:D

now this one,wow im sick of them,idle is good part throtte is good and wot is good,just not putting the fuel were it needs to be;)evenly dist.god help me
 

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HawaiianJet - no disrespect was meant to you personally. The second statement I quoted from you gave me a good chuckle - you wrote that well. LOL.

Much of what I do is making and/or selling carb spacers to dyno shops/engine builders/individuals therefore since I have advanced study in these, lol, I just try to give pertinent info when talked about.

They are all about the intake manifold and carb transition. Therefore they can greatly effect one or both, and sometimes not at all. Many different specific applications out there (especially when you add in restricted rules 2bbl racing) and many universal of course. As an example, between mine and the HVH Super Suckers I sell / consult on I have somewhere near 40 or so different one's. Long Gone are the days of just having 4 hole (or two hole for 2bbls) and open spacers.
 
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