strugles to go over 95

[Purple440]

Did you nail down an rpm range where it lets up? 

[mally69]

not an exact rpm,  but its right around  4800 to 5000 is where it starts to level out, but from there it takes forever to climb the slightest amout of rpm.

[firefighter3931]

so, basically i should raise my float level and try it again???   primary or secondary?

Check them both....with the engine running at idle you should just see fuel start to drip out of the site holes when you remove the plugs. 

What type of fuel filter are you using ? 



Ron

[mally69]

I have site glasses on mine, its a mighty demon 750 i have them set just under half way right now...
As for the fuel filter, i have the on that came with the fuel rail, its been in there since last year..
here's  what filter i have

http://store.summitracing.com/partdetail.asp?part=SUM%2DG3121&view=1&N=700+

[firefighter3931]

I have site glasses on mine, its a mighty demon 750 i have them set just under half way right now...
As for the fuel filter, i have the on that came with the fuel rail, its been in there since last year..
here's  what filter i have

http://store.summitracing.com/partdetail.asp?part=SUM%2DG3121&view=1&N=700+

Pull the filter and see if it's clogged up. That doesn't look like much of a filter.....are you not running an inline cannister filter ? Have you been able to test your fuel pressure ? For a test i would pull the fuel filter out and take it for a quick blast and see what it does. If the problem goes away you found the issue. Your float levels are fine BTW....middle of sight glass is correct for Demon carbs.

For some reason te fuel delivery is not keeping up with the demand. You start off in first gear and it winds up nice....but as the bowls are emptying the fuel supply is not able to keep up. That's probably why it's laying over at high speed. 


Ron

[mally69]

I have a fuel pressure guage right on the rail it bounces around quite a bit, but it reads between 7.5 and 8.5 in that range. Now that you guy's have pin pionted the lack of fuel problem, ill toy with it until i get it right..   Thanks..

[70charger_boy]

Cool, good luck

[bordin34]

Is your gas tank venting?

[mally69]

Is your gas tank venting?

Venting?  im not sure never checked on that, how would i check that?

[The70RT]

Is your gas tank venting?

Venting?  im not sure never checked on that, how would i check that?

After you run your car a bit take off the gas cap, if you get a rush of air going in it isn't venting.

[mally69]

yes, it has done that before at the pump when i went to fill it up.  but not everytime. thats somthing i never thought to check, ill get a wire and run up the vent on the side of the tube and see if it comes out..  keep the ideas coming I will check every idea  and evenually we will get it straighned out.

[The70RT]

yes, it has done that before at the pump when i went to fill it up.  but not everytime. thats somthing i never thought to check, ill get a wire and run up the vent on the side of the tube and see if it comes out..  keep the ideas coming I will check every idea  and evenually we will get it straighned out.

Maybe blow some compressed air in it after you run your wire.

[mally69]

ok vent hole is clean BUT i noticed somthing,,  when my car is at idle i have fuel being pushed into my vac advance line for my distributer, would this mean a blown power valve???  would that cause this to be happening???   

[firefighter3931]

Fuel should not be pushed through a vacuum port. It sounds lke you have an internal leak....check the metering block gaskets for tears or damage. 


Ron

[Musicman]

While your busy chasing your tail around, you might also want to remember that just because you can get 6000 RPM out of your car in 1st and 2nd, that doesn't necessarily mean that you will get to 6000 RPM in 3rd. Remember, the faster the car is moving, the more atmospheric pressure (wind resistance) it has to overcome. It takes a lot of effort to row a square boat up a river of mud, and that's just what your engine is doing at top highway speeds. Personally, I think your okay where your at... If you want faster highway speeds, change your gears, or install a GV unit... Get yourself out of the HP band, and back into the torque range.

[mally69]

While your busy chasing your tail around, you might also want to remember that just because you can get 6000 RPM out of your car in 1st and 2nd, that doesn't necessarily mean that you will get to 6000 RPM in 3rd. Remember, the faster the car is moving, the more atmospheric pressure (wind resistance) it has to overcome. It takes a lot of effort to row a square boat up a river of mud, and that's just what your engine is doing at top highway speeds. Personally, I think your okay where your at... If you want faster highway speeds, change your gears, or install a GV unit... Get yourself out of the HP band, and back into the torque range.

true and a very good point,
but last year ive taken it up to  115 mph,,  ill take the carb off and see whats up with it

[Musicman]

10 MPH...    a good tune up will give you that. 

[mally69]

this is a mighty demon 750 that im running   will it use the same gaskets and power valve  as a holley double pumper

[firefighter3931]

this is a mighty demon 750 that im running   will it use the same gaskets and power valve  as a holley double pumper

Probably not....check with Summit racing though. 


Ron

[squeakfinder]

Maybee its time for a bigger carb.

Not trying to change the subject (but probably will) where can you drive 95 to 110 mph without being thrown in jail? Unless your talking about the autobahn or open road racing. 15 mph over the speed limit is considered reckless driving where I live.

[mally69]

yea its called wreckless driving here to,  i live out in the country  or on the out skirts of a large town and there are long straight streches 

[The70RT]

Maybee its time for a bigger carb.

Not trying to change the subject (but probably will) where can you drive 95 to 110 mph without being thrown in jail? Unless your talking about the autobahn or open road racing. 15 mph over the speed limit is considered reckless driving where I live.

Doing burn outs is too...........I'm sure we all have done that though.

[mally69]

I jetted my secondaries down 2 sizes and my primary's 1 size. Its was burning extreamly rich, and still needs to go down some. I put the vacume advance for the distributer up to the vac port that is operated by the power valve, it was hooked up to the other one. No internal leaks that i found.  Seems like what i did helped, it will just walk right up the rpm range with no more flattening out

[firefighter3931]

That sounds better ! 

Have a look at your plugs and make sure they aren't fouled. 



Ron

[mally69]

Ill take # 1 out tomarrow and see what she looks like.  i ran it around for about an hour last night and before i got home i opened it up pretty good, so i should have an accurate reading.  Ill check.