Depressing Dyno results. Need advise

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sbh126

sbh126

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Gentlemen,
Well I finally got a chance to do a dyno run and was not impressed with the results. I peaked out at 265 hp at 4500 rpm. and 305-315 torque from 2700rpm through 4400 rpm. As soon as I hit 4500 she starts popping and running really lean.
74 duster. The motor is a rebuilt 440, 10.6 to 1, schumacher headers through dual 3in flomaster mufflers. stealth heads, mild cam, dual plane eddy intake, holley 4160 750 with vacuum secondaries. 3.55 rear gears and 4 speed manual.
The guys that were running the dyno told me I needed to get a 750 double pumper and an electric fuel pump and that it should solve the issue. He suggested a demon 750. He also said I needed to run 3/8 fuel line to the tank.
I was using the interactive carb selector on holley's website and it said not to use a mechanical secondary double pumper unless the vehicle is less than 3100 lbs. From what I understand the 74 duster was about 3300 lbs and I have a big block. (lots of aluminum parts though)
I need some more opinions on what parts I need to buy before I go wasting my money on junk I dont need. What would a better carb be? Why are my numbers so low? Please help.
 
Fuel supply needs addressed for sure. What is your distributor and how is your vacuum advance hookup?
 
72BBSwinger said:
Fuel supply needs addressed for sure. What is your distributor and how is your vacuum advance hookup?
Click to expand...

The distributor is a plane jane autozone one. Brand new though. I have one from 440 source that I plan on swapping. Vacuum advance is hooked to the front passenger side inlet of the carb.
 
Might check on condition of fuel filter and or fuel tank pick up before putting effort and money into replacing pump and fuel lines.
 
3/16 fuel lines and that carb should support more than 265 rwhp.

Check everything over for vacuum leaks.

What have you got for ignition?

Carter "Street" fuel pump works fine on my car.

Steve
 
She needs a 3/8 fuel line for sure. Seen it many times when some one goes from a 318 to a 440 and does not change it.
 
Which dual plane intake, Performer or RPM? And just how mild is your cam?

If you have a fuel delivery problem, and it sounds like you may, fix that before you go swapping carbs. A 750 should be OK for at least 100 more HP than you have now. And, tuned correctly a vac secondary carb will make the same HP as a double pumper (but Holly Double Pumper sounds more like a **** star).
 
5/16 fuel lines arent going to support a built 440 like that. Its running out of fuel when you get the RPM up. Remember you lose a good % in the drivetrain. What are the cam specs?
 
are you getting fullthrotle? reason i ask is,that if you dont get to full throtle you will pull enough vacum at higher rpm to close the powervalve and motor runs like absolute crap at higher rpm.. this is something i learnt when a throtle cable stretched alot just before breaking..
 
I have built 440,383,340, 318,360's...

Honestly the fuel line is fine those dyno guys don't really have a cluse, but they knew it was easiest to convince you that the fuel line was the problem.
dbl pump would be fine, if you can use your foot just right
I've put a 440 with 2'' primary headers, .530 hyd 286* 110* sp 830 annular holley double pumper, 5/16 fuel line stock fuel pump, nd it rev's fine to 7000rpm

I have pics of the car still and motor, it's a 68 dart.

either fix the timing, fatten the carb jetting and or have a look at the valve springs, cause they could be floating.

and try a different dyno shop, cause they aren't helping you by giving sht for advice.
 
I ran an 11 second 'Cuda with a 800 Holley on 5/16 line................

It's something else.

So far as needing a DP the two carbs flow essentially the same. Once you get your foot down, that fact that it's a double pumper means nothing

You've either got a fuel restriction---cap, pickup, restricted line, hoses, etc, or not enough pump, or vapor problems

This is assuming that the "dyno guys" are right about it going lean and that it's not also/ or an ignition problem
 
C130 Chief said:
Which dual plane intake, Performer or RPM? And just how mild is your cam? QUOTE]

I have a edelbrock performer rpm dual plane intake. here's a link to the one I have.
http://store.440source.com/Edelbrock-Performer-RPM-Intake-Manifold-RB-Engines/productinfo/146-1000/

As for the cam, its a custom ground cam. here's the specs I have.

Grind: HIFLOW1H
LOBE SEPERATION ANGLE : 108
OVERLAP : 80
INTAKE OPEN : 40
EXHAUST CLOSES : 40
INTAKE CLOSES : 76
EXHAUST OPENS : 76
RUNNING CLEARANCE : 0.00 HOT
VALVE LIFT (INT/EXH) : 0.472 / 0.472
DURATION (INT/EXH) : 296 / 296

CHECKING FIGURES AT .050 TAPPET RISE
OVERLAP : 12
INTAKE OPENS : 6
EXHAUST CLOSES : 6
INTAKE CLOSES : 42
EXHAUST OPENS : 42
DURATION INTAKE : 228
DURATION EXHAUST : 228
LOBE LIFT INTAKE : .315
LOBE LIFT EXHAUST : .315
INTAKE CENTERLINE : 108
ROCKER ARM RATIO : 1.50
Click to expand...
 
1wild&crazyguy said:
either fix the timing, fatten the carb jetting and or have a look at the valve springs, cause they could be floating.

and try a different dyno shop, cause they aren't helping you by giving sht for advice.
Click to expand...

What timing should I be running? I dont know what I'm currently running. I just put it were it seemed to run fine.
What do I need to do to "fatten the carb jetting"?
There is another dyno shop in the town south of me that I'll give a try when I get these issues worked out.
 
67Dart273 said:
You've either got a fuel restriction---cap, pickup, restricted line, hoses, etc, or not enough pump, or vapor problems

This is assuming that the "dyno guys" are right about it going lean and that it's not also/ or an ignition problem
Click to expand...

I think I'm going to run new lines just so I can know for sure that its taken care of. I'll change the filter and I think I'm going to go ahead and run an electric fuel pump. This is the fuel pump I'm looking at getting.

Holley 12-150 HP series
http://www.summitracing.com/parts/HLY-12-150/

And the pressure regulator.

Holley 12-803bp
http://www.summitracing.com/parts/HLY-12-803BP/

Does anybody have any experience with either of these products? Is this a quieter fuel pump? Anything else I might need? What should I have my pressure set at?
 
sbh126 said:
How do I check this? I believe I have stock valve springs that I pulled from a 77 new yorker.
Click to expand...

If you have stock springs in the heads that could be your problem. More then likely the springs are old, worn out or just don't have enough rate to open and close the valves like they should. Get a set of springs that match the requirements of that cam
 
Yes, new valve springs for sure. If those are from a 77 they are old and tired, I would do that first.

You need to know where the timing is not just where it ran good, buy a timing light and and a damper tape so you know for sure. I would have already done the 3/8 fuel line and electric pump but I don't think that is your major problem assuming the pump is in good working order.

I have found most off the shelf carbs are too lean for a Mopar, they set those things up for Chevy so get yourself a jet assortment kit for your next dyno visit, richen up the carb jets 2 numbers at a time until the power drops off and then go back one number at a time until you get the peak power point.

Spark plug heat range is also another factor to examine as is the stock ignition, but since your set up is very mild the stock box may be OK, I would probably go with an orange box or an MSD 6al though and an MSD coil.

You should try some spark plugs are few heat ranges colder and hotter, examine them carefully after a dyno pull to check for signs of detonation, overheating and air/fuel ratio. Do some interweb searching on this and you'll find some picture examples to go by.
 
I wouldn't start throwing money at without going back to the basics. As GJ stated your probably floating the valves with those old springs. What about the valve train? Push rod length ok? Rocker arms or adjustment? Definately add an electric pump and a low restriction fuel filter but I wouldn't change fuel line diameter yet without testing fuel pressure and flow after you go electric pump. My 3 cents.
 
Make sure the secondaries on the carb are opening. You may need to swap a lighter spring in it to get them to open fully.
 
sbh126 said:
C130 Chief said:
Which dual plane intake, Performer or RPM? And just how mild is your cam? QUOTE]

I have a edelbrock performer rpm dual plane intake. here's a link to the one I have.
http://store.440source.com/Edelbrock-Performer-RPM-Intake-Manifold-RB-Engines/productinfo/146-1000/

As for the cam, its a custom ground cam. here's the specs I have.

Grind: HIFLOW1H
LOBE SEPERATION ANGLE : 108
OVERLAP : 80
INTAKE OPEN : 40
EXHAUST CLOSES : 40
INTAKE CLOSES : 76
EXHAUST OPENS : 76
RUNNING CLEARANCE : 0.00 HOT
VALVE LIFT (INT/EXH) : 0.472 / 0.472
DURATION (INT/EXH) : 296 / 296

CHECKING FIGURES AT .050 TAPPET RISE
OVERLAP : 12
INTAKE OPENS : 6
EXHAUST CLOSES : 6
INTAKE CLOSES : 42
EXHAUST OPENS : 42
DURATION INTAKE : 228
DURATION EXHAUST : 228
LOBE LIFT INTAKE : .315
LOBE LIFT EXHAUST : .315
INTAKE CENTERLINE : 108
ROCKER ARM RATIO : 1.50
Click to expand...

Your cam's "intensity number", the difference between the advertised duration and the duration at .050 lift is only 68. That's pretty tame for a performance cam. You should be looking for something with a number between 40.5 and 52 or so. I'd talk to the cam grinder immediately about that. If he doesn't understand the theory, go somewhere else. At 296 degrees, the cam's advertised duration is pretty stout. But at 228 degrees, the duration at .050 is pretty mild. It doesn't even need a performance torque converter. Your cam grinder tried to give you the best of both worlds and you got neither.

Once you put a real camshaft in that engine, you'll have to correct the fuel delivery problem for sure. The guys are right about the fuel line. Replace it.
Click to expand...
 
1970duster said:
if you have stock springs in the heads that could be your problem. More then likely the springs are old, worn out or just don't have enough rate to open and close the valves like they should. Get a set of springs that match the requirements of that cam
Click to expand...


x2
 
Before you start throwing expensive pieces at the car, do some detective work and find out where your problem really lies. You can do most of this yourself with a few basic tools and a couple test drives. Don't give that dyno shop any more of your cash.

Tools: Get a timing light, a vacuum gauge and possibly a fuel pressure gauge. You should be able to get all 3 for under $100, and you'll need these to do any sort of tuning. Oh, and a stopwatch.

Fuel delivery: Replace all rubber lines, especially anything on the suction side of the pump. Pull the pickup out of the tank make sure the sock isn't clogged with crap. A decent mechanical fuel pump will do fine, a cheap Pep-Boys special won't. Go electric if you want. 5/16" line should be OK, but the factory used 3/8" on 440 cars. If the line itself is in good shape, it's probably not your problem.

Test drive: Set the timing to something sane like 10 BTDC and leave it there for now. Make sure the FLOAT LEVELS are SET CORRECTLY on the carb! Splice the fuel pressure gauge in the line between the pump and carb. Where the fuel filter was is a good place. You want a long enough piece of line on the gauge so you can tape it to the windshield and watch it while driving. Start the engine and note the pressure. Now drive around nice and easy. Pressure steady, no leaks? Find a nice quiet country road and floor it in 2nd or 3rd until it breaks up. How's the pressure, does it drop off? You'll see a little drop, but if it goes below 3 PSI, you have a fuel delivery issue. If it stays around 5 PSI look to valve float.

Valve springs: When you say stealth heads, you mean 440 Source aluminum heads right? Not sure what springs they ship these with, but they should be fine with that "mild" cam. In fact an OEM 440 spring should do OK. How does that "custom" cam base circle compare to stock? Lifter preload?

Cam: Bear in mind that a stock 440 cam had about the same .050 duration, and similar lift. Therefore you can expect similar power/RPM with the cam you have now, but less low RPM torque, and a rougher idle. That said, 350 HP, 5000 RPM at the wheels would seem more reasonable. Who knows what the numbers that dyno shop would show. 14 seconds on a country road quarter mile would be ballpark.
 
Sounds like you have a multitude of problems none of them sever but they do need addressing. Fuel yes, Cam for sure needs addressing you can buy a nice Mp cam that will make all the power you want off the shelf for your setup, but most of all change those valve springs, if they are not the problem now they will be later when one breaks and dumps a valve, buy them new don't take a chance. Also make sure you have pleanty of spark for that motor, there are many different options for this as mentioned above. But before you just start changing things go back to basics set Timing with a light, check vacume with a guage, make sure carb is opening all the way, make sure you have a good plug reading nice and brown, if these things all check out then go on to the others.
Good luck i'm sure you will get it sorted out, tuning takes time and patience. My gut feeling is your cam is not correct for your setup.
 
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