Do I have too much carb?

[taco502001]

Ok I have been having this problem with my car since July of this year where the car keeps fouling out the plugs and i mean fast.  I recently had a shop do alot of work to the car and spent around 2 grand on it and still am fouling out plugs but doesn't seem to happen as fast now.

Here is the setup its in my dodge demon which tips the scales at 3100lbs

440 9.7:1 compression ratio

Forged rods, crank, pistons, recently rebuilt holds great cylinder pressure which is the same across the board

ported and polished open chamber 906 heads

this info from comp cams
HYDRAULIC-Serious street/strip effort.
Hyd. Hyd. 3000 to 6200 21-242-428 292H
intake292 exh292 intake/exh@.050 244 244 lift.501 .501 lsa110°
383 needs 3000-3500+ stall. 440 needs
2500-3000. 750 to 800 CFM carb. &
headers 3.91 gear up.

Intake is single plane weiand team g

Carb 825cfm Race Series Demon carbeurator

Hooker 2" fenderwells to 3.5" exhaust

Junk B&M 3k stall

8 3/4 3:23 suregrip rear end

Built manual reverse valve body 727

Complete MSD setup and cleaned up all wiring


I have tested the voltage to wires right at the box the large red and small red see a minimum of 12.25 volts at idle it increases as the rpms increase, timing is locked out at 32*, has new blaster2 coil, taylor thundervolt50 wires, ngk fr7 plugs gapped at .018.   I understand that my voltage should be more steady but i think the march pulleys have something to do with it.

Anyways lately the car is still running way too rich and having carb backfires which normally points to timing but it is locked out at 32*,  plus if it was electrical or timing wouldn't problem be there the whole time not just after i have driven the car around for a while.  I was also told that with the race series carb that when held at part throttle for a while due to mech secondaries and boosters and shit that it just dumps the fuel in when there is no real need for it.  If this is true that part throttle driving can cause problems could it be the 2+ hrs of driving it around on the highways at 3000 rpms that fouled the plugs out and that there is really nothing wrong with everything?

[Dartdragracer]

What size jets are you running in your primary and secondaries?

Do you have really good ground wires on everything?

MSD 6AL ignition?

[Capt Jack]

my first reaction would be to ask how youre driving it.  a lot of low speed cruise?  then yeah, might be too much carb, especially if, being a 'race' carb, they jerked the idle circuit around much.  if youre cruising surface streets a lot with that much motor, the 3.23's might not be the best choice.  3.55's min is what I see for that motor.  3.91's (as recommended) even moreso.


try a 750 vac secondaries on it and maybe go back to some sort of advance system on the ignition. 

a tinkers damn

CJ

[NYrr496]

Yeah, get the advance back in the distributor.  When you're driving on the street with the 323 gears, you're turning the engine pretty slow. The engine needs a load on it to clean out. I've always had better luck with vac secondary carbs on the street.

[taco502001]

cars wiring was all cleaned up by the shop new fuse panel installed fuel pump and aftermarket accesories have there own circuits.   So yeah grounds and wiring is good, yes its a 6al box, and probillet distributor with timing locked out like I said at 32* I also eliminated ballast resistor from system.

As far as carb is setup I have no idea trying to get a hold of this guy scott marrison is pretty hard to do he is always working on other projects that are i will admit seem to be more profitable and important to him than mine i mean you have to make your money.

but yeah as far as idle feed restriction, jets, power vavle size etc.. is unknown, I was told by him that the throttle cable also seemed to be acting up and not opening the butterflies all the way allowing all the fuel but not the air,  he also mentioned charging system.  But as i said I tested the voltage on all connections it was 12.25 at idle rises when rpm rises I think its low at idle due to march pulleys.

But yeah most of my driving was street but I do get on it occasionally but from the shop to home was a one hour long drive on the highway so thats an hr at 3000rpms and he said that the race demons at part throttle like that can cause a flooding condition I dont know if that is true.   I am just trying to find out whats causing this problem if its nothing but that i drove it that long at part throttle and it flooded the plugs or if the carb is too much and not setup right.

[bOb shingler]

have you checked vacuum at idle and have you installed the correct power valve? with one to small it will open at cruise speeds and richen up. the carb sounds like it's to rich on both the primary and secondary circuits but check idle vacuum first. 32* to me is not enough timing. open the plug cap to .035" also.

[taco502001]

I dont want to be chasing my tail around so to speak if there is really nothing wrong with the car but just the simple fact its meant and setup for wot all the time and that with my highway cruising and shit without ever doing any wot passes or anything caused the plugs to foul.

Yeah I have no idea and do not have tools or time to do all the testing thats why i paid this guy 2 grand to take my car diagnose it and perform repairs, I had the gas tank sumped, new inline filer, pump relocated, fpr is set at 6 psi he was suppose to setup and tune carb on chassis dyno, he also installed the msd setup and performed compression tests and etc.....   

I would have thought for 2 grand and him saying its done I shouldn't have to try and fix this problem he was suppose to fix especially be told these problems and him not have taken care of them even though knowing about them oh well

[NYrr496]

You just said it. Locked out timing is a track mod. Your carb can be made to work, but everything else has to be right first.

[taco502001]

but if the car should see say 20* initial and 38* total with 18* mech advance the timing should be working at idle then to help clean things up also this car does not get warm at all the son of a bitch hardly sees 180* temps averages 160 when driving.  Plus if the msd system is seeing the voltage it requires and is wired up properly doesn't this mean that the ignition system is working?  That my problem is something else other than electrical or ignition.

As plugs fouling out is one of 2 things normally too much fuel, or not firing the fuel being given to it and if the timing is fine and voltage and wiring is good it should be somewhere else correct?

I appreciate the replies guys I can only do the tests I know how to do and with the tools I have.  I am just trying to find out of this is carb related or still in ignition/charging system?  As I said everything is wired up properly and the msd system is seeing 12 volts minimum as is what I am told it requires, and it has all new wires, plugs, cap, rotor, coil, etc...  I just dont see how as he mentioned a bad battery can cause it as battery is mainly used to start the car if alternator is working properly and everything than battery does not play role.


I am just saying I dont see how or think it can be anything ignition wise b/c if any of that was causing the problem these backfires and driiveability issues would be present all the time would they not?  I mean car runs damn good everytime you put new plugs in it, it is only after driving car for a period of time cruising around plugs foul and car runs poorly.   With new plugs this thing roasts the mickeys all day long

[NYrr496]

I had a 440 running very rich and fouling plugs because it was idling in the driveway while I was setting it up. Once I took it out, it cleared up considerably. You need to get the temp up to 180. It's inefficient any lower than that. You definately have a fuel problem. Like bOb said, get a vacuum guage on that thing and then check your power valves. Are your transition slots/ throttle blade relationship correct?  Read some Car Craft articles on carb tuning. There's certainly no shortage of those. You're gonna go broke payin' that guy to work on your car for you.

[fasttcars]

plugs gapped at 0.018?.....is that a typo......has the engine been dyno tuned?.......jets in the carb altered?........just cuz the ignition is locked dosen't mean  you can't put more timing into her....obviously the guy tuning it wasn't a mopar guy setting it at only 32  go to at least 35{total}....but will probably like some more cuz of the comp and cam.....NOOO the engine dosen't need to be 180 degrees to be efficient  big block's  prefer to be around 160  degrees.....actually around 140 is where they make the best power tbc.............

[speedymopars]

I'm with bOb - the power valve could be causing this issue.

What is your idle vaccum?

Also, with the plugs gapped so small, it would make the carb seem a bit rich.

[ksdartguy]

Yes, I agree, sounds like carb tuning will fix it.
1st check power valve and float levels. These will both cause excessive flooding.
The Demon should have changable  idle feed restrictors. You can lean the idle fuel mixture.
You want to be able to kill the engine by turning in the idle screws all the way.

The plugs should be .035- 0.45 with the MSD.

The timing would be better with some advance, although it shouldnt make alot of diff on idle.
I would put about 20 in it and advance it to 36-38 by 3000 or so.

Rick

[taco502001]

But if it was timing or an ignition/electrical system problem how come thing runs like raped ape when new plugs are installed no backfiring or cutting out or anything.

It only acts up after driving an extended period of time and that the plugs become fouled. It is the reason why they are becoming fouled that escapes me as i did not perform the work to the carb scott marrison did. He replaced gaskets, power valve etc...

Plus my car turns over really easy with locked out timing, and wouldn't timing being locked out help burn cleaner at idle. Plus my car never overheats or gets hot.

from what i have gathered is plug is a colder burning racing application plug and gap is only at .018, I am going to throw a hotter plug and raise gap. Change battery keep an eye on the voltage make sure msd is getting propper voltage etc...


I am just trying to see if it was just driving on the highway for 2hrs at 3k rpms with this type of carb or if its something more.


I agree it should be around 38* total for timing, and it needs hotter plugs with a larger gap,  I dont want to do this and put new plugs in if they are just going to get fouled out again just because the style of carb.

[Tubbed440]

Definately go with a hot plug, and get that gap increased to at least .035.  Try that and see how it does.  IMO, you're not going to do anything but chase your tail until that issue is solved.


In all honesty, if you want to drive it on the street, I would do like the others have said.  Unlock the mechanical advance...and if you got one, hook the vaccum advance up.  Just by tuning all that in with the carb, the mileage will go through the roof and your eyes won't burn at stoplights anymore. 

[Crazy68Dart]

Taco, listen to what the guys here are suggesting, rather than asking the question and then politely disagreeing.  Your going to have to get your hands dirty if you want to figure out what the problem is.  They have some good suggestions and tests for you to perform.

[Prodart]

On the race demon carbs modifying the IAFR will also modify the fuel curve. A easy tesy is blow out the IAFR jets(closet to carb gasket)
you can then take some small dia. wire .018 +or - wrap it around the vent and put the ends in the jets. This effectively will cut the stock.035 jets down leaning the idle and part throttle curve.If it helps then order some blank jets from Jegs and pin drill them. Usually .022 is a good starting point. If you do the wire trick just make sure to wrap the vent a couple of times to keep the test wire in place.This is easier then changing the IFR jets. And much better then drilling the butterflys

Hope this helps some, The most important thing is to make sure you have the correct .020 of transfer slot showing. Also if you have
the Idle-eze base plate bottom the screw out lightly then open it up 1 1/2 turns for the stock setting.

Mark

[67 dartgts]

--------------------------------------------------------------------------------

Taco, listen to what the guys here are suggesting, rather than asking the question and then politely disagreeing.  Your going to have to get your hands dirty if you want to figure out what the problem is.  They have some good suggestions and tests for you to perform.

Crazy68Dart said that.   
 
  Maynard

[oldkimmer]

U need 38* timing, a hotter plug gapped at least to 30, actually first off u need a mopar guy or gal to dial it in..........shelf the race carb for later...750 vaccum will do wonders for it........also make sure ur preload on the lifters is correct......kim.........

[WarLocK451]

I would get that single plane race manifold off of it and put an RPM performer on instead. It would totally increase throttle response, low end and mid range power and flows upto 6500 RPM. There really is no need for a race single plane manifold like a team G on a mainly street used motor because low end velocity will suffer drastically... especially if the Engine is only 9.7 compression with that cam. What's your cranking presure? I'm also thinkin that your cranking pressure is down due to overlap.

I also have to agree with bob and some of the other guys, get that distributer working right (locking it is generaly used in drag racing) and get a good vacuum reading and use the appropreit powervalve.

If all else fails...try a holley. I had a buddy that had a similar problem and switching from a demon to a holley corrected the problem. I've heard some negetive things about demons (summit racing dropping them for one) and had my own personal experiences with them...I also know that people have had good luck with them.

[dusterdarryl]

demons are rated different to holleys, an 825 demon is more like a 900+ holley, but that dont mean it wont work,  but them plugs gota be .035, maybe more with an MSD, fouling plugs quickly has to be a carb issue, what size p/v dose it have in it? knowing what demon carbs are like it may just be too bigga p/v for regular street driving,
does it clean the plugs if your on the highway?? if your can loan a 750 v/s off a mate and try it I bet you would like it, next question would be jet size?

[NYrr496]

If you try the dual plane RPM, the big carb will work better, but there is no one magic cure. You need to sort out the timing, the carb, the plug gap...

[taco502001]

Well what sucks is I am not the one who assembled this motor or performed the work, I mean i know how to change and read plugs etc....  But i do not have time tools or knowledge to do much else.   You might call me crazy but for shits and giggles I pulled the 7s on the drivers side and cleaned them up best I could I raised the gap to .045 and put back in.  Since my exhaust is true dual no x pipe or h pipe I started car up and let it run for a short time.  I noticed alot less carbon and shit out of drivers side exhaust than compared to passengers.  Eventually I will put some ngk fr5s in and gap those .045/

And no it did not clean up with highway driving that is what seemed to cause the problem, I think between those problems there and the carb I can get this car to work.  But I think the way I drive mostly street driving and cars setup is mismatched I am going to try a edelbrock victor/performer with a quickfuel carb with vaccum secondaries.  The timing locked out should have no effect but produce a hotter and more full burn at idle but I agree I will try and get it to 38* total

[NYrr496]

DON'T try a Victor. A Performer RPM is what you need. With 323 gears you have no need for a single plane manifold. Listen, I was young once and the way I learned things was to dive in and do them. PLEASE try this: Instead of paying someone to set up your car incorrectly, go to Sears and buy some tools. You'll be shocked at how inexpensive Craftsman tools are. Your car money will go much farther if you do your own work. Address ONE task at a time. First one: swap the intake to a dual plane. Try the car. If it works a little better, play with the carb, try the car, then the timing, try the car. YOU CAN DO THIS.

Would you rather pay someone two grand to work on your car or buy two grand worth of trickness in a box??

[Crazy68Dart]

DON'T try a Victor. A Performer RPM is what you need. With 323 gears you have no need for a single plane manifold. Listen, I was young once and the way I learned things was to dive in and do them. PLEASE try this: Instead of paying someone to set up your car incorrectly, go to Sears and buy some tools. You'll be shocked at how inexpensive Craftsman tools are. Your car money will go much farther if you do your own work. Address ONE task at a time. First one: swap the intake to a dual plane. Try the car. If it works a little better, play with the carb, try the car, then the timing, try the car. YOU CAN DO THIS.

Would you rather pay someone two grand to work on your car or buy two grand worth of trickness in a box??

Shaazaaam!   

Listen to him, once you have the tools and knowledge no one can take it away... legally anyway... *clears throat*.

[NYrr496]

Taco, Hot Rod on the News stand right now, the one with a 69 Firebird on the cover. They're building a 383. This month they assembled the shortblock and heads. Next issue: they're going to test a truckload of swap meet intakes. This article has your name written all over it. It should be titled "383 How To for Taco".

[dusterdarryl]

dont use a victor unless you have a high compression, high head flowing, big cammmed, high stalled, low geared drag strip beasty, by all means use an RPM, but just a plain old v/s holley will be pretty darn good for your streeter, I used a 750 v/s on my 440 in my 68 C body, it worked perfect

[JD451]

I just installed this carb i got off e-bay on the 440, its off a 502 BBC crate, 80/80 jets, 6.5/4.5 PVs, it runs great, all i did was set the floats & adj. the mix screws, it seem to have more power then the 3310-780 i just took off

http://cgi.ebay.com/ebaymotors/ws/eBayISAPI.dll?ViewItem&ih=018&sspagename=STRK%3AMEWN%3AIT&viewitem=&item=280156213623&rd=1

[dusterdarryl]

an 850 v/s !! wow now your talkin, what a great carb for a 440, its a wonder there is not more of those around

[PureGTS]

Sounds like a jetting issue or a fuel leak into the venturies or bad float setting (too high). MAke sure everything is tight on the metering blocks and the level is right and look down the carb throughts to see if it is dripping at idle. If so adjust the flaot level and or check the fuel pressure and see if the pump is blowing the needle off the seats allowing too much fuel in.