i have been down 7 jets and and according to the plugs it is richer then ever. what do you think is wrong i am leaning towards a power valve but i don't know. i have a speed demon 750 ts (same as double pumper) and my mods are in my sig.

 

couple things to check....

1. power valve, be sure the diaphram is good and most importantly, be sure the gasket on it is good, any leakage here will just drip fuel into the base plate under the blades.

2. blade to transtion slot area, very important that not more than .020-.040 thousands under the blades showing and that both frt and rear blades are set the same amount. carb`s from 2001 and newer have an idle ease adjustment under the carb stud, this allows extra air into the engine without leaning out the idle circut.

3. meter block to carb body, be sure they seat nicely without a gasket, if there is any old residue from old gaskets and what not the block can leak internally. make sure the carb has the correct metering block gaskets also.

4. fuel bowl level, keep this at the center of the sight no higher, also use a flashlight to be sure it stays in the center of the sight while idleing.

5. fuel pressure should be no more than 6 1/2 pounds

6. air bleeds free of dirt...any debries that have lodged into the air bleeds will richen the mixture drastically, be sure to have them free and clean.

7. mixture screws should be 1- 2.5 turns out any less than 1 and the circut is too rich for other reasons, more than 2.5 out and the circut is too lean, make sure all of the idle screws are out by the same amount.

8. most important is ign timing, many performance cams will require a base of 14-18 degrees, the higher you can run the timing the more vacuam you`ll create at idle, this will help the situation greatly.

do some checking and report back, this should be a no brainer to fix.

 

Well I went to check the timing (about 12* base)and it was running poor but it was running. Then I went to clean up the timing tab because it was dirty. I went to start it to get a more accurate measure, and when I took my foot off the gas it would die. So I pulled a plug and it was the most fouled I have ever sean a plug. I put the plug back in and an hour later, right i made this thread, I tried to start it again and it back fired bad. So now I have the carb in pieces on the bench

 

ive got a 650 demon on my 406 and it also always ran rich, it came with 70 78 jets i went down to 68 76 and its been fine ever since. Get your timing just right and go from there. Also check your vac at idle when you get it running decent select the correct power valve for your engine.

 

can someone suggest a power valve i want to get this put back together and running right

 

power valve is dependent on engine vacuum, so hook up a vacuum guage and report back with the idle reading.

 

the thing is the carb is off of it and the fuel boles are off of it. i am going to put a new one in it so i might as well get close now.

 

Once a spark plug is "carbon fouled" it will continue to fail reguardless of jetting. The only cure is to replace the plugs with new ones. Most plug fouling is an ignition problem or a carb idle circuit problem. main jetting is not the cause.
A blown power valve will cause fouling too. Put the stock jets back in. You're barking up the wrong tree.

 

Well using that extreme energy cam you gotta have a good 11- 13 inches in N...drive is where you want to check on how much vacuam you have and then go at least a inch lower on your power valve. I`d say a stock 6.5 inch would probably be fine, if you think you have less vacuam that what I mentioned you could go to a lower one to delay the power circut say a 5.5 or even 4.5 valve.

 

the timing is about right and in the higher revs it screams

my ignition mods are
msd 6al
msd blaster 2 coil
non computer controlled hei distributor
plug wires are ok about two years old stockers about 5k miles
plugs have been everything form ac delcos to champion to autolite.

 

inspect the rotor for burn thru. both sides. inspect the cap too. Check the msd unit by quickly grounding out the white trigger wire. should make a good spark off the coil wire to ground. check the ignition wires with a ohm meter. regap the plugs to .035"

 

1 i replace the stock power valve with a holey 5.5

2 forgot to check that one

3 they seamed to fit good and put new holy gaskets in it

4 the level is slightly below the line in the middle

5 i have a stock fuel pump

6 i took an air compressor and blew them out

7 timing is about 12*

i just put on new accel 8.8 wires and a new cap and a holy 5.5 power valve and the plugs are fouled after 3 miles

 

Right there is a lot of the problem, your going to need more base than that, try 16-18 degrees, I`m running a 1090 king demon with a 270 @ .050 cam and it`s needing 20-24 to even idle

 

i also forgot to hook up the vacuum for distributor but that would make it want to run lean wouldn't it. also the break hose is not that great where can i get some good hose.

 

how hard would it be to do a complete rebuild i don't really want to do it but i want to get it to run right and don't want to buy a new carb.

 

barry grant recommends 18-24 base timing for it to run. id bump the timing up some

 

You don`t need a new carb unless you`ve broken it in half and even then you could part it back together, you probably don`t need to rebuild it either, you just need to tune it, they sell that carb to guys using it on 283`s- 502`s and all other displacments of other manufactuers.... now all of these engines couldn`t possibly use exactly the same carb so You have to tune it to your engine and tune your engine to that carb, pay a good performance shop to tune it instead of wasting money on another carb that`ll act the same.

 

It's pretty simple....

{Edited by Moderator}

Nothing is wrong with your carb except it's too big for the application.
{Edited by Moderator}

 

i have read the sa how to win with demon carbs it doesn't explain how it got richer when i went down jets i am starting to think it is the metering blocks but i don't know.

 

more bad news for me the base of the carb is warped by .065 how should i go about fixing that.

the rear passenger front driver is how it rocks back and forth

 

Are you sure it's the carb baseplate and not the manifold?

You can buy a new baseplate assembly about $150.00

{Edited by Moderator}

 

no i can't be sure if it is the base plate i am just hypothesising

 

i will probably buy the book but here is my dilemma how can i have a huge vacuum leak yet still be rich it is mind boggling and it is the same with the jets. and i know it is rich because it smells rich, the air fuel gauge says it is rich, and most importantly the plugs come out jet black.

i am trying not to be critical here but you are coming on a little strong. i am only 20 but you are treating me like a 16 year old, and quite frankly you don't have the post count or name recognition to treat me like that. I know your going to say what dose post count have to do with anything, and you would be right post count has nothing to do withe anything except i would consider some of the more prominent members friends. i will allow a friend to take a shot at me in good fun if i deserve it knowing that i will take a shot at him later in good fun.

 

good news i was mistaken the rocking was caused by the hose clamp on the break vacuum line i guess it is get rid of the hose clamp or spring stile one.

 

even with my idle mixture screw in almost all the way it still is rich at idle

also i can watch it lean up to normal at moderate throttle on my air fuel gauge.

 

increase the idle air bleed sizes by .o30`s that`ll lean out the idle circut..that is all.

 

how do i do that, do i drill it out if so with what type of drill bit

 

You can buy blank air bleeds through Jegs then drill out to the size you need. Stock on a speed demon 750 on the primary side is .070 and secondary is .063. So just add .030 to the number and that's the sized hole you need. Whether you need to do both primary and secondary or just the one side I don't know. Just a regular drill bit the right size is all you need.

 

i thought the speed demons air bleeds where not replaceable like the race and king demons are or am i thinking of something else.

 

Well, I had a baggy that came with my Speed Demon that had air bleeds. Can't remember if there were some installed already or you just press them in. My new Mighty Demon has screw in air bleeds.

 

Find a good local carb guy to teach you. Do not drill anything untill you are positive that it is nessary. please have someone in person teach you or tune it like said before. tell him what you want and let him do it

carbs are your worst nightmare or best friend, mine is my best frien heavily modifed on my 327 in the 68 camaro, and my power band dose not kicjk in untill 4200 rpms, got to love the stick

gb