Why no power at high rpm?

[euroZ06]

Hi,

So Saturday, I finally decided to convert my old kickdown linkage to lokar, and I did the lokar throttle cable as well. In the past I had an issue with low power levels up at higher rpm, and I was hoping the new set up would fix this... but it didn't. When I go full throttle, the throttle lever on the carb pulls all the way. If i'm in neutral and I floor the car, it happily revs a bit past 5k rpm, however when i'm in gear, it really struggles past 4k, and it pains me to get it to 5k. I have a holley carb (fairly small) with electric choke. I didn't install the throttle lever adaptor, but I do have it... I just didn't see how to install it with the lokar kit, and since the throttle opens all the way when I floor it, I didn't see the necessity. Maybe i'm missing something? wrong geometry with just lokar kit?

Overall, I am not happy with the lokar kit. The throttle cable snapped out of its binder 3 times, leaving me stranded and trying to refit it in the middle of the road. I don't think transmission can be properly adjusted without doing the drilling on the valve lever (I read somewhere that I need to drill another hole in the middle of the lever to make it work well). It will not shift at redline, and shifts at 3.5k rpm when i'm WOT, but normal cruising it shifts at 2.5k rpm and shifts hard too. So if I pull the cable even more, i'm just pulling when its shifting at normal driving.

[Y1CHARGER]

If you hold the car in 1st gear and you can't get it to rev up to 5k then it sounds like you have engine problems, not transmission.  I would check to see if your throttle is opening all the way.   With car off and someone sitting in the car holding the gas pedal to the floor while you check under the hood.

[euroZ06]

If you hold the car in 1st gear and you can't get it to rev up to 5k then it sounds like you have engine problems, not transmission.  I would check to see if your throttle is opening all the way.   With car off and someone sitting in the car holding the gas pedal to the floor while you check under the hood.

I've used a stock to make throttle all the way open, and then looked. It is in full open position. I also noticed that at about 85% open, there are two nozzles that start squirting additional fuel. Also, when car is in neutral and I floor it, it easily revs past the redline on the tach (5k rpm). If I manually put the car in the first gear, I can get it to 5k rpm, but it is painstakingly slow after 4k rpm... feels like not enough fuel or air, or something. The car runs really well though, always starts on the first try, and idles really well, never dies on me. Is my timing off? should I adjust for more fuel in the carb? 

[74Rallye]

Do what Y1CHARGER said first. After that I would guess is that the carb is going lean at high rpms or you have a big dent in the exhaust system, maybe a weak ignition, Worn out cam.
What engine and carb are you running?

[euroZ06]

Do what Y1CHARGER said first. After that I would guess is that the carb is going lean at high rpms or you have a big dent in the exhaust system, maybe a weak ignition, Worn out cam.
What engine and carb are you running?

It does get to 5k rpm, it just takes a very long time. The car gets to 3.5k rpm "quick", then starts running out of breath, at 4k it starts to die slowly until it gets to 5k rpm.... from 4 to 5k, seat of the pants feel is lethargic, like there is no power. Mind you, at low rpm, it is very healthy and has ton of torque, and if I mash the pedal it will do a long burn out (open dif).

[John_Kunkel]

Basically, you removed parts that work just fine and replaced them with junk. 

[Y1CHARGER]

What engine and carb are you running?  Did it ever run strong?  I'd check/change fuel filter and check fuel psi. 

[375instroke]

My stupid opinion is fuel.  I had a road course car that was sluggish, and people a the track told me that Holleys can get a resonance in the fuel pump that causes it to self pump at certain RPMs at WOT, and they were right.  This would only occur in an RPM range, so it went away as RPM increased.  I've also had fuel pumps that couldn't keep up with the volume required.  Acted fine unless held at WOT for several seconds under load, then the motor would stumble as the fuel bowl ran out.  Does it stumble at all, or still run smoothly, but just lack power?

[euroZ06]

Basically, you removed parts that work just fine and replaced them with junk. 

it was not working before with the stock levers. The reason I did the project in the first place was because my throttle cable broke, and I already had the kickdown kit laying around.

[euroZ06]

My stupid opinion is fuel.  I had a road course car that was sluggish, and people a the track told me that Holleys can get a resonance in the fuel pump that causes it to self pump at certain RPMs at WOT, and they were right.  This would only occur in an RPM range, so it went away as RPM increased.  I've also had fuel pumps that couldn't keep up with the volume required.  Acted fine unless held at WOT for several seconds under load, then the motor would stumble as the fuel bowl ran out.  Does it stumble at all, or still run smoothly, but just lack power?

it runs perfect, very smooth idle, drives great under 3500rpm, after that its like there is no more power.

[400sforever]

I don't want to sound stupid but back in the day I had a similar problem. .my fuel tank had some crud in it and eventually plugged the fuel filter and didn't show signs until hard acceleration. .might be worth ruling that out if you haven't already

[will]

Fuel pump pushrod was my problem. It was too short and would fall flat on its face above 4000 rpm. Let off the gas and it was fine. I replaced that one item and haven't had the problem again. I have the lokar kit too, luckily you got yours to work. I hate that stupid thing.

[Y1CHARGER]

My stupid opinion is fuel.  I had a road course car that was sluggish, and people a the track told me that Holleys can get a resonance in the fuel pump that causes it to self pump at certain RPMs at WOT, and they were right.  This would only occur in an RPM range, so it went away as RPM increased.  I've also had fuel pumps that couldn't keep up with the volume required.  Acted fine unless held at WOT for several seconds under load, then the motor would stumble as the fuel bowl ran out.  Does it stumble at all, or still run smoothly, but just lack power?

it runs perfect, very smooth idle, drives great under 3500rpm, after that its like there is no more power.

Doesn't sound like it runs perfect to me.  Are you going to answer anybody's  questions or try anything people are suggesting or just keep ranting and wasting our time.  Good luck

[euroZ06]

My stupid opinion is fuel.  I had a road course car that was sluggish, and people a the track told me that Holleys can get a resonance in the fuel pump that causes it to self pump at certain RPMs at WOT, and they were right.  This would only occur in an RPM range, so it went away as RPM increased.  I've also had fuel pumps that couldn't keep up with the volume required.  Acted fine unless held at WOT for several seconds under load, then the motor would stumble as the fuel bowl ran out.  Does it stumble at all, or still run smoothly, but just lack power?

it runs perfect, very smooth idle, drives great under 3500rpm, after that its like there is no more power.

Doesn't sound like it runs perfect to me.  Are you going to answer anybody's  questions or try anything people are suggesting or just keep ranting and wasting our time.  Good luck

I have answered the question.

So I should look at the fuel pump? How do I check which one I have and which one would I need to replace it with?

[John_Kunkel]

Before replacing any more parts I'd suggest a little troubleshooting; if you suspect a fuel delivery problem, hook up a pressure gauge to the carb inlet and see if the pressure drops off significantly about the time the car loses power.

[Bronzedodge]

^^ This, what John said.

I also noticed that at about 85% open, there are two nozzles that start squirting additional fuel.

Sounds like your accelerator pump nozzles.  They are retained by a gasketed screw, just inside the edge of the air horn.  They should only discharge fuel when the throttle is moving - unless you mean something else.

What is your initial and total timing?  What rpm does it come "all in" by?  Do you have a vacuum gauge?  We can guess over the internet all day. Need gauges, measurements.

[RallyeMike]

Start with the basics. Fuel and spark, ... easiest to hardest. We can guess all day. Solving it is a process of hands on elimination.

Check timing mechanical advance 2500rpm car in Nuetral.

The fuel:

Fuel filter clean?
Visual check of fuel lines to make sure no pinches
Fuel pump pressure?
Blow out fuel lines with compressed air
Lastly - Tank pickup sock because it is the most work.

You can eliminate fuel tank, line, and filter in one shot by connecting your fuel pump intake to a can of gas temporarily.