No top end power, need help

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EmersonC

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So I've recently noticed that I am really lacking in the top end power. When I open up the throttle the last 1/4 has no power gain, and if I let off the throttle a bit I have more power. Im thinking it might be timming? I am currently running at 10 degrees BTDC. The book says I whould be at 5 (I think) but it does not run well at 5. It also is a bit rough at idle, and I have tweaked with the idle mix screws and cant get it to run super smooth. It doesnt die at idle, but does run rough and once it hits a little higher RPM it smooths out nicely.

Specs:
66 dodge dart 273 automatic
Edelbrock 4 bbl (600cfm I think?)
3.22 rear end gear
6a MSD box
Mallory distributor with new spark plug wires (solid core)
Runs on the cool side, but my guage may be off.
Uses a ton of gas, but that is expected with a 66 (around 13 mpg but my odometer doesnt work so I cant easily check the mpg.
I think it was originally a slat 6 but had the 273 when I bought a few year back.
 
You need to figure out how much advance you are getting out of the distributor. Whats the timing when the engine is at 3000RPM?
 
10 BTDC, is not enough for anything but a stock engine. If you have any kind of stepped up cam, put more initial on it. Search around here on how to set it, vacuum gauge, strater kickback... and then adjust mechanical in distributor to hit your total number.

True solid core wires are not suggested when running an MSD box.
 
Unless you have one wild - *** cam, that thing should do WAY better than 13. I don't drive "carefully," and my 67 got 17 and some more with

(now 318)

360, 727, 3.89 Ford 9" rear, 28.+ tall tires, about 3300 at 70 mph

Little cam "about" like a 340 stick cam, Ed performer, Ed 625-650 carb

Letting off and "getting more power" might be too lean, too much carb.
 
Hey guys, I agree completely on the timing aspect of his tune, but i'm a little puzzled on the last 1/4 of wide open throttle. I'm wondering if secondary side is way lean or way rich. Maybe even the opening rate is way off. Last time I saw what he described was on a Q-jet that the air valve was just flopping open on full throttle. I'm just bringing it up for conversation as i'm not a Eddy guy by any means....:D.
 
Retarded timing usually adds to top end power. I'm going with a fuel issue.
 
So I just messed with the timing, tried 15, 20 ,25. Drove it and nk notible improvements. Started getting some pinging at 20/25. Currently set to 15. I don't have a tach so can't test at 3000. As i retarded the timming the rpm kept climbing, all the way to about 25 or so
As far as fuel goes. Sometimes the fuel filter emlties after sitting over night. And it was a used car BTW.
 
OldmanRick said:
Hey guys, I agree completely on the timing aspect of his tune, but i'm a little puzzled on the last 1/4 of wide open throttle. I'm wondering if secondary side is way lean or way rich. Maybe even the opening rate is way off. Last time I saw what he described was on a Q-jet that the air valve was just flopping open on full throttle. I'm just bringing it up for conversation as i'm not a Eddy guy by any means....:D.
Click to expand...

Which is the secondary side???
 
EmersonC said:
Which is the secondary side???
Click to expand...

The rear two barrels on the carb........ Your normal driving uses the front two. When you get toward wide open throttle, the rear (secondaries) should progressively open as the load on the engine increases.


P.S. A picture of your carb, or at least the numbers off it would probably be helpful at some point. Check the base plate, should look something like this...........
 

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What exhaust do you have on this car?
 
Sounds like the secondaries may not even be opening. Sometimes the air blade gets stuck in the closed position and won't open even though you floored it. I found this on my GTX, as the engine coughed at WOT but ran great just under that.

Also, check to ensure that the gas pedal has enough travel to fully open the throttle. I found once that WOT couldn't engage the secondaries due to insufficient pedal travel.
 
68gtxman said:
Sounds like the secondaries may not even be opening. Sometimes the air blade gets stuck in the closed position and won't open even though you floored it. I found this on my GTX, as the engine coughed at WOT but ran great just under that.
Click to expand...

I took a quick look at the secondaries and they move freely. this doesnt tell me though if they moove while the engine is running. another thing I will check this weekend. Guessing I can just have the car in park witht the air cleaner off and open the throttle and I should see the secondaries open up (hopefully)?
 
EmersonC said:
As i retarded the timming the rpm kept climbing, all the way to about 25 or so
Click to expand...

What about this? As I retearded the timming the RPM kept clmbing all the way up to aout 25 degrees BTDC. I say "about" becuse the marker on the flywheel only goes to 15 degree....
 
EmersonC said:
I took a quick look at the secondaries and they move freely. this doesnt tell me though if they moove while the engine is running. another thing I will check this weekend. Guessing I can just have the car in park witht the air cleaner off and open the throttle and I should see the secondaries open up (hopefully)?
Click to expand...

Well if you hold open the top plate on the secondaries, while a friend is flooring the pedal (with the engine and key OFF), you should be able to see the secondaries open down below. Ensure they open fully or readjust the pedal linkage so that they do. Then in the future, if you don't feel the secondaries kick-in, test the top plate to see if it is sticking closed.

The top plate is vacuum actuated, so when the secondaries are opened,the top plate ensures that only the amount of air the engine can use is actually released to the secondaries (in simplistic terms).
 
EmersonC said:
What about this? As I retearded the timming the RPM kept clmbing all the way up to aout 25 degrees BTDC. I say "about" becuse the marker on the flywheel only goes to 15 degree....
Click to expand...

When you Advance the timing the RPM go's up not retard......Right???
 
Cudafever said:
When you Advance the timing the RPM go's up not retard......Right???
Click to expand...

Ya sorry, got mixed up there for a moment. Does that sound right that the rpm would continue to climb as I advance the timing all the way to 25 BTDC
 
UPDATE:

I tried tweaking with it and still am having trouble. I noticed that by having the timming up around 15* I seem to be getting a little better upper end power. What Im trying to get a handle on now is the idle. It is rough (still drivable) and at stop lights I pop it into neutral but still runs rough, especially after it has come up to temp.
I borrowed a cheap SunPro Tach II and hookaed it up and my idle is at 3k. I tried all sorts of things (timming and idle mixture) to get it down, but it really does not want to drop below 3000 (according to the tach). The carb is a used edelbrock 1406 0693 and I checked the secondaries and they seem fine. At full throttle they are open all of the way.

At 3k RPM there was no noticeable suction coming out of the left side vacuum port of the carb. But at a higher RPM the vacuum does kick in and is fed to the distributor.

And like I said earlier my MPG is bad, in the low teens. Any ideas/what next
 
if its tough to time and you get no top end power the timing chain might have
jumped a tooth. it also might account for the poor fuel mileage, just sayin.
 
I'd be backin' up a step or two.

Use a piston stop to verify timing marks are accurate.

Do some checks for sloppy timing chain.

Use a delay timing light, "crackedbacks" idea of temporary "timing tape" from masking tape, or just sit down and scribe some degree marks on the balancer, so you KNOW where and what the timing is doing.

Regardless of "what the engine likes" it should run pretty fair "on top end" at 34-36* total timing, no vacuum, until you get this sorted out.

And take the trouble to "map" out what the mechanical advance is up to, IE too slow, sticky, rusted shut, and check the dist. for wear.

THEN after you know what the timing and spark is doing, go after the fuel.
 
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