strugles to go over 95

[mally69]

I took my charger out yesterday and decided to wind it up, I have  a mild built  440 4.10 gears with a 275/60/15 tire, It goes through all 3 gears fine but  it seems like when i get up to 95 mph it just struggles to go any faster  it doesnt miss or flutter or anythiing   it just seems like the rpms kinda stay in place and does not keep climbing    I just dont understand     (not a tranny issue that  i am aware of )

[aifilaw]

you have 4.11 gears and a tire that's what, 28in in diameter?
Sounds like you got a great 1/8mi track car... but your hitting 5500-6000 RPM at what, 95-105mph?
that's why you can't go faster, your engine is maxed out, keep it at that much longer and you'll blow it up. Those gears are meant for the street or the track. and you are probably through the first two gears in the first 250 ft.

[mally69]

actually i think you are right when i looked down at the tac, it did read about 5500 6000 rpm

[70charger_boy]

Geeze, my little cheesy 318 can go over 100 mph 

[Todd Wilson]

Geeze, my little cheesy 318 can go over 100 mph 

Mine will to!  Heck my old 74 Dodge pickup with a 440 and 4.10's will go 100mpg with more in it although the truck didnt like it! 



Todd

[70charger_boy]

Geeze, my little cheesy 318 can go over 100 mph 

Mine will to!  Heck my old 74 Dodge pickup with a 440 and 4.10's will go 100mpg with more in it although the truck didnt like it! 



Todd

Oh yeah, well I can reach 140 mph taching at only 4,000 rpms 

[mally69]

i thought with 4.10 i could go a little more than 100

[Rolling_Thunder]

fuel starvation may be an issue...     high rpm's = lots of fuel...

[The70RT]

fuel starvation may be an issue...     high rpm's = lots of fuel...

Yep and too little fuel at high RPM = burned pistons.

[70charger_boy]

Are you running an electric fuel pump or mechanical?  My friend ran into the same problem with his hemi and went with a high volume mallory electric fuel pump

[Runner]

how big of an air cleaner do you have?   are your secondaries working?.     try taking the air cleaner off then see if it runs out of power.     i once tried a k&n stub stack on my old 383 and when it hit 5200 rpm the car would just level out and wouldnt rpm any higher,   pulled the stub stack off and it would spin 6500 no problem again.   there just wasnt enough room between the top of the air cleaner and the stub stack to provide enough air to pull any higher rpm.   

   28 inch tire, 4.10 gears and 101 mph should only be around 5k

with a 28.5 tire, 4.10 gears my roadrunner trips the beams around 119 mph (dependeing on the weather  give or take a mph) at about 5900 rpm     i think you have a air flow or fuel flow problem.

[mally69]

i am running a holley mechanical 110 gph and 3/8 fuel lines  i pulled a few plugs and they are a flat black (not brown or white)   my cam is also on the advance mark would that matter in this situation?..
i am running a 14x3'' edelbrock air cleaner. 

[aifilaw]

sounds like
A. you need to do some tuning
B. your engine ran out of RPM's, use shorter gears if you want to go faster

[70charger_boy]

sounds like
A. you need to do some tuning
B. your engine ran out of RPM's, use shorter gears if you want to go faster

[firefighter3931]

Nobody has mentioned valve float. Will it pull 6000 rpm in any of the lower gears ?

I would try experimenting in 1st gear and see how high the engine will pull. 



Ron

[The70RT]

Nobody has mentioned valve float. Will it pull 6000 rpm in any of the lower gears ?

I would try experimenting in 1st gear and see how high the engine will pull. 



Ron

Im suprised no one has brought that up yet....good point

Probably a stupid question but are you getting full throttle?

[mally69]

tomarrow morning ill take it out and run 1st gear and see what rpm it pulls

and ill also check to see if im getting full throttle right now and let you know..

[mally69]

yep,  when the petal is down the carb is open full 

[SeattleCharger]

 

[mally69]

ok i took it for a ride this morning and this is what happend..   i can shift out of 1st 2nd at around 6200 rpm no problem getting there   pulled pretty much the whole time,  but in high gear i found that it will go about 5000 fairly quick but to go from there to 6000   it seems like takes FOREVER to get there   i dont get it

[mally69]

 

[firefighter3931]

It's running out of fuel....start by checking your float levels.

When you installed the fuel pump did you install a new fuel pump pushrod ?



Ron

[mally69]

yes i did, i got it from 440 source..  Just a qeustion, if its running out of fuel shouldn't it sputter or miss a little or not ?

[Rolling_Thunder]

hit or miss...    I have run cars to top end and they simply did not climb in RPMs - others almost stall due to sputtering and such

[mally69]

ah ok i see, that seems to be what happening to me. It  just struggles so hard to keep climbing in rpms.

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

[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.

[mally69]

OK i checked the plugs, for the most part they are stilll flat black..

[firefighter3931]

OK i checked the plugs, for the most part they are stilll flat black..

It appers to be still running rich. It could be overjetted or possibly your ignition system is weak.

First thing i would do is pull a plug wire and ground it while turning the engine over. What you want to see is a nice blue/white spark. A dull orange spark means the ignition system is weak and this will cause it to run rich.

Second thing is to replace the plugs with a fresh set. If they were fouled it's often difficult to get a descent reading on the jetting w/o replacing them. What's the engine combo ; heads/cam compression etc.... what plugs are you running in there now ? How is the timing set up ?


Ron

[mally69]

PLugs are auto lites factory head range.
440  30 over  with 10.4 compression
906 heads decked 7 thousanths not ported
1.5 ratio roller rockers
hooker super comp 1  3/4 headers
full 3 '' mandrel bent exhaust with an  X pipe
comp 292 dur .501 lift     244@.050   cam is (advanced)
4.10 gears
tci 3000-3500 stall  street fighter convertor
TM-7 intake
mighty demon 750
mopar coil and distributer (mopar chrome ignition box )

Timing is set up as far advanced as i can get it Without valves rattling or pinging.. I was already told that mopar ingnition is junk.

[firefighter3931]

That's a good healthy build.  The MP orange boxes are suspect but the chrome boxes are descent. I would still check the spark quality and see what you've got. If the spark is strong (blueish) then throw a fresh set of plugs in there. Personally, i like the NGK xr-5's for iron headed 440's. You might be jetted rich or the plugs could be too cold (heat range) for your combo.

Fresh plugs will give you an idea of where the jetting is. 


Ron

[mally69]

Ok, ill buy a set tomarrow and plug them in and see what ive got. But ill check my spark color first, then migrate to town

[firefighter3931]

Ok, ill buy a set tomarrow and plug them in and see what ive got. But ill check my spark color first, then migrate to town

Good plan. After you get it fired up assuming the spark is strong....drive it for a few miles on just the front barrels (only) and pull over. Pull a plug and see what you've got....this will tell you if the primary jetting is too fat. If the plugs are black...you're too fat...pretty obvious.

Once the primaries are dialed in you can move onto the secondaries...full throttle for 5-6 seconds and shut it down immediately. Pull a plug and have a look see. adjust jetting accordingly.

Have fun ! 



Ron

[mally69]

Thanks