Fuel stink ?

[chevguy65]

Ok,

With the help of Tom, Ed and Donn I got my carb fairly well dialed in.
It runs better than it ever did, but I did put on a new Demon 750 and removed the Holley.

Anyway, the thing is I cannot lean the carb anymore than it is without it running rough and stumbling, it is in the zone...hehehe...but it stinks enough to burn the eyes if you stand behind the car and it is turning my exhaust tips black from the carbon.


What do I need to do?
BTW. I am running an electric fuel pump and pressure is set to about 4 1/2 to 5 lbs.

[bjuice]

they way you describe the exhaust ..etc...there is NO question the carb is way tooo FAT ( RICH)...What size front and rear jets do you have ?

remember fuel pressure at the regulator will not determine the lean or richness of your carb..only your main jets...and if you have a power valve it could effect the rich side your smelling...

you also need to bring that fuel pressure up to a minimum of 6 to 6.5 lbs sitting there idling..remember you got it dead headed sitting there against the regulator..so it will drop a minimum of 1 lb or more under full throttle....anything under 4lbs is dangerous of burning an engine up...even the factory Hobb switches ( fuel saftey switch) is pre-set at 4lbs from the factory...this means when the fuel pressure hits the 4lb mark the hobb switch will kill the circuit its wired to stopping everything in its tracks...most hobb switches are wired into the NOS fuel side for extra saftey in killing the NOS in case the fuel pressure drops to a un-safe level ( 4 lbs )

Brian

[topsportsman1]

Also Carl,
You may need to tune the idle air bleeds,but that should be done with precision.Just don't let anyone do this,as .003-.007 bigger will make a differance on the idle richness

Also,turning the air screws in leans it,Out richens it,so try to get the air screws all set the same,between 1 turn and 2 turns,If that won't cure it,I'd say the idle air bleeds need tuning



*EDIT*

[gdmii]

Don't know anything about Demons but are they backwards? On a Holley turning the idle mixture screws in leans it. Just wondering.

George

[topsportsman1]

Don't know anything about Demons but are they backwards? On a Holley turning the idle mixture screws in leans it. Just wondering.

George

Yes you are correct George,I had it backwards,I wasn't thinking...as always

[gdmii]

I wasn't thinking...as always

Just a brain fart. :D I have them on a regular basis.

George

[topsportsman1]

I wasn't thinking...as always

Just a brain fart. :D I have them on a regular basis.

George

All apart of getting over the hill.I seen it hapening quite alot lately :P :P :P

[chevguy65]

Thanks for the replies.

Brian the jets are 73 front ant 84 rears.
I will set the pressure back up to 6lbs.

I have adjusted the 4 corner idle screws about as lean as I can.
Any leaner and it starts to stumble and die.

The funny thing is, the engine loves the new carb, I am seeing a major improvement in low end acceleration as well as more top end pull.

As far as the air bleeds I need to find a carb guy I can trust, and no one here in town fits that bill, at least I have not met them yet...lol

I will try these things and again appreciate all of your help, I am getting to where I am doing more and more work myself and this is definately something someone that knows there stuff needs to help me with.

Thanks again guys!!!!!!!!!! 8)

[margaritaman]

Carl, Have you adjusted the "idle-eze?"

http://www.competitionplus.com/04_15_2004/bg_idle_eze.html

If I can get mine to idle with two Demons at 950 rpm using the idle-eze screw then so can you. Mixture at idle is ~ 13.2:1

[bjuice]

Carl, Have you adjusted the "idle-eze?"

http://www.competitionplus.com/04_15_2004/bg_idle_eze.html

If I can get mine to idle with two Demons at 950 rpm using the idle-eze screw then so can you. Mixture at idle is ~ 13.2:1

WOW !!..that show queen is THUMPING at 632 @ 111 mph...very impressive for a car that looks and drives like it does..my hats off to you !!!

[chevguy65]

Carl, Have you adjusted the "idle-eze?"

http://www.competitionplus.com/04_15_2004/bg_idle_eze.html

If I can get mine to idle with two Demons at 950 rpm using the idle-eze screw then so can you. Mixture at idle is ~ 13.2:1


Thanks Jeff, I had forgotten about the idle-eze.
I got in such a hurry and did read about it, but I forgot....duh.

I will try adjusting it today.

[margaritaman]

WOW !!..that show queen is THUMPING at 632 @ 111 mph...very impressive for a car that looks and drives like it does..my hats off to you !!!

Thanks Brian. It was a long journey, but the outcome was worth the wait. Of Course now it will only get faster.

Carl, you should be able to introduce enough air into the motor with the idle eze to lean it out.

[margaritaman]

Carl, I sent you a couple emails too, but for those suffering from Demon demons I'll post it here too.

To open the idle-eze turn the screw counter clockwise. But first turn it clockwise until it bottoms out. Then turn it 1.5 to 2 turns counter clockwise which should give you a decent baseline.

Another thought is your initial advance. Demons love initial advance to the tune of 18-20 degrees. I don't remember what you were doing for an ignition system, but if its an MSD distributor its as easy as running the initial up to 18 and then place the appropriate colored bushing in the distributor to limit your mechanical advance.

[chevguy65]

Thanks Jeff,

good info all the way around.

I will put a timing light on it this afternoon.

[edvancedengines]

Well you didn;'t say which Demon 750 cfm you have but to my way of thinking those jets are far too rich for any of the 750 's I know about.

Ed

[chevguy65]

Well you didn;'t say which Demon 750 cfm you have but to my way of thinking those jets are far too rich for any of the 750 's I know about.

Ed

Ed it is the speed demon mech secondaries.
I could jet it down some.

What would be a good suggestion?
My holley had 70 78's and it seemed to starve for fuel on the top end.

Maybe 70 front and 80 rear?

[bjuice]

Carl my wifes 406 is making about what yours makes...i have a 750 holley on hers and i run it 74 square...

the best way to make jet changes is 1 size no more then 2 jet sizes at a time..outside of the obvious ( sitting still reaping raw fuel).....when you make a pass at full throttle..kick it into neutral and kill the car at the end of the track..if someone can towe you back great.. or you have a spot you can pull over on the end of the return road to where you can pull out a few plugs and see how they look.....never drive back to pits and try to check them..the drive back will distort the plugs from their true reading at WOT......

if the plugs are black and sooty ( wet looking) then you know right off hand your too fat ...and work back from there...


i wasn't trying to butt in too much and dominate the reponses..but it sounded to me from post one it was over jetted..

Brian

[chevguy65]

Thanks Brian,

I was wondering, but see some guys running 72-80 etc and was under the impression that I was in the ballpark.
But it was info from a source that I have found less than knowledgable.
Meridian auto in Meridian Idaho to be exact, I would not let them work on my lawnmower from what I know now.

[bjuice]

I hear ya..at least all that was hurt was maybe a few fouled out plugs..you can always get away with being too fat..but the too lean will make you pay the fiddler...lol

seriously..the air is a little different ( a-lot) different out where you are from...so if i were in your shoes..i would start out very conservative...say
74/79 and see how it acts sitting there idling...you can always lean it out more if you need it..you should find a little crisper throttle response as you lean her out...like i said go 1 no more then 2 jet sizes at one time...
also in the winter you may need to fatten it back up but again 1 no more then 2 jet sizes..
i personally think your about 5 to 6 jet sizes to large on the rear..if not more..but just slowly tinker with it..it will tell you when its right..if your looking at the plugs etc.....oh yeah you can buy those jet kits from ADVANCE OR AUTO ZONE reasonable..will have all the jet sizes you need for that 750

if you haven't bought you a HVH SUPER SUCKER yet please get you one..you can really tell the difference ..get the 2 inch aluminum..the plastic is not recommended for cars seeing a little street use..(could melt)..its also at a good time for one for you cause you may have to richen your jets when installing these bad boys cause it increases air flow. ( if your jetting was right to begin with)..try it you'll be very pleased for the money spent...

also where ya got your timing set ?

[chevguy65]

I talked with a guy by the name of Compton tonight.
He spent about 15 years with Edelbrock in R&D and now has a performance shop here in town.

He is going to do a performance tune on the car for me.

Once he gets it dialed in he is going to show me how to tune it correctly. I keep missing the boat...lol

I hear ya about to lean...seen a few engines go by-by that way.

The Super-Sucker will have to wait until I can get a good 4" cowl hood.
I already put a nice ding in my hood from the air cleaner stud when the engine torqued over.

I have less than 2 inches of clearence.
I have the change slated for next spring. and will add the super sucker then.
I have already looked at the aluminum ones and they look bad ass...

http://marine-performance-parts.com/images/products/detail/SS41502AL.jpg
for about $100.00

Thanks again to you and everyone for the help.

I really am trying to do a lot more myself, but when I get this confused it's time to let a pro take over.
Once I get it learned, re-learned, then no sweat, but I have to see, feel, and do it once before I commit it to memory...lol

[margaritaman]

My favorite line:

Plugs are cheaper than pistons!!!

[chevguy65]

My favorite line:

Plugs are cheaper than pistons!!!


LOL...you got that right!!!!!! :shock:

[bjuice]

Hey Carl there is nothing wrong in getting someone to help you with something as long as you learn from him /her so you know where to hunt the next time out..all of us had to learn from someone at sometime.
i say your making a very wise choice by getting him to help you..
also they make a 1 inch super suck as well..

Brian