First off, I haven’t driven the Dart as much this year as previous summers due to crappy weather, and other non typical obligations. Starting recently, and I can’t say exactly, whenever I give the engine WOT for a long pull out on the highway to pass a car, or just dust off the cobwebs, once the engine returns to cruising rpm & throttle position I can smell gasoline fumes. I don’t remember this from last year.

On top of that fume thing, fuel consumption seams to be up when driving at low rpm in traffic, say sub 2000 rpm. Fuel gage needle starts a free fall, and although previous years I got crappy in town mileages, this year it is worse.

The last two tanks of fuel yielded firstly 227 miles at14.9 mpg which was 150 miles of 3000 rpm @ 60 mph, and 70 miles of suburban & in town driving 40 mph and less. Today’s trip to a car show consumption was 18.4mpg over 225 miles. 80 miles of it at 3200 rpm 60-65 mph, 110 miles at 2600 rpm 50-55 mph, and the balance a few miles of stop & go up to 35 mph.

It is clear that higher rpm, and speed increase fuel consumption due to the aero- brick styling of a 67 Dart. Perhaps secondary’s are cracking open at 3000 rpm causing more consumption even though the purple or black spring is currently installed on secondary diaphragm.

Back to the fume out-gassing aspect: Would a too high of a fuel bowl float level cause fuming, and reduce fuel mileage?

Big cam overlapping cam must not be too efficient at low rpm, as thin engine lopes big time 1000 rpm & under, and barely ticks over at 600 rpm in gear or stays running. So I’m sure a lot of fuel is just running through the engine while at idle unburned. Also when coasting down hill, or backing off abruptly after hard acceleration, there is a lot of popping & farting coming from the tail pipes, and this two I suspect is wasting fuel.

I just occurred to me that perhaps the accelerator pump’s diaphragm is leaking causing fumes.

Perhaps I need to rebuild the carburetor again, and or bump up timing a whisker to bring up in gear idle speed another 100 rpm to 700 to squeeze out some of the lope.

Once again, getting this Holey to settle into a decent state of tune and staying there is problematic.

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67' Dart GT Convertible; the old Chrysler Corp.
82' LeBaron Convertible; the new Chrysler Corp
07' 300 C AWD; Now by Fiat, the old new Chrysler LLC

So what do your plugs look like ? Drive at 35 miles an hour , shut off the engine , coast to a stop and look at your plug . This is one place to start ,
Is the accelerator pump adjusted with a small gap ? What size idle jets are you running ? What size squirter ?
There is some good stuff on Holleys on You tube . Worth taking a look , takes a lot of the mystery out of tuning .

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The only thing original is the serial number and data plate.

So what do your plugs look like ? Drive at 35 miles an hour , shut off the engine , coast to a stop and look at your plug . This is one place to start ,
Is the accelerator pump adjusted with a small gap ? What size idle jets are you running ? What size squirter ?
There is some good stuff on Holleys on You tube . Worth taking a look , takes a lot of the mystery out of tuning .

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The only thing original is the serial number and data plate.

Gas smell could just be a fuel leak consider my holley390 after it got a coule years old the fuel bowl bolts kept backing out causing it to weep fuel from the bottom of the fuel bowl gasket.
Yes the float level can cause gas flooding i also had that problem the lock nut on my front fuel bowl would back off and the screw would vibrate loose pouring fuel from the screw hole in the throat.

Kev

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It could be gaskets, last time I had the bowls off, the gaskets did not release very well. I have had that relic (Jan 1993) apart for tuning twenty times or more in the last three years or 8000 miles.

I’m going to pick up a new rebuild kit, hopefully Holley is now making replacement gaskets resistant to today’s alcohol laced fuel.

Another item that needs to be addressed is the secondary metering block. I wonder if it also needs to be changed to something that flows a bit more fuel to compensate for this ethanol polluted fuel. Any thought on this.

To answer the question asked previously about jetting, etc. the set-up is as follows:
Holley Trick Kit #37-720
Accelerator pump #25, orange cam, #2 hole
Jets= #57, 2.5 power valve
Secondary spring; purple
Backfire ball installed
Drilled throttle plates 3/32â€￾

This combination has proven to be best performing, and economical.

Soon I will have an o2 sensor installed, and will know for sure where air fuel mixture is under all driving conditions.

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67' Dart GT Convertible; the old Chrysler Corp.
82' LeBaron Convertible; the new Chrysler Corp
07' 300 C AWD; Now by Fiat, the old new Chrysler LLC

Fuel smell could be rich mix or a bit of fuel sputtering back out the carb due to intake reversion. I have noticed this on some tuneups of my motors.

Lou

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Home of Slant6-powered fun machines since 1988

How did it run with smaller jets ? I got no bog running with the 54 jets and it seems to have no shortage of fuel . Got a 31 squirter though .
The new Holley kits seem to be more forgiving . I used the same blue gasket several times and it is still looking good , the ones in my old kits were good for about 2 changes and then would no longer seal .

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The only thing original is the serial number and data plate.

Wow. Your setup wouldn't run on any of my slants.

That 2.5 PV is part of the problem. Your going to have to run huge primary jets to cover power.

Drop to 54's, stick a PV about 2" lower than cruise vacuum, and stick with Orange. Unless you have a big bump in displacement and compression, go with screw position #1. 10:1 go with #2. I run the highest numeric number possible. With the 10.5 I was pulling nearly 24 mpg with the Holley. I pull about 20 with the Carter. But then I run short gears now, and can't keep my foot out of it.

But that's just my experience. What do you have for jets in the secondary? Should be a 56 or so. I think the plate was a 9, but can't remember off the top of my head. What metering block do you have on the primary? Never had to drill plates in a 390, but never ran one to good effect on the stroker.

2¢

CJ

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Part of Tyrde-Browne Racing

CJ,

I have been following Holley’s recipe for power valve selection, basically half of idle vacuum. I run 3 to 8in Hc in gear idle fluttering needle. I have tried the following PV: the plug; 1; 2.5; 3.5; 6.5, and 8.5 in conjunction with # 51; #57; and #60 jets. Compression is 9.5:1 calculated when I had head work done a few years back from actual mesurements..

I had to drill throttle plates as there was no idle mixture adjustment available, screws were all the way out. I progressively drilled in 1/32 increments to 1/8 inch, and settled on 3/32â€￾ yielding best mixture screw response.

I don’t know what the flow rate is of the secondary metering block—no PV in the circuit. I’m guessing it is their standard block what ever that equates to in jet size. Also I don’t know the rating of primary metering block--- probably standard size. How dose one determine metering block ratings?

Current cruse vacuum is 12 to 16 “ Hg. 2000 to 3000 rpm, with 3.55:1 rear gear. That vacuum gage takes a big nose dive into single numbers with slightest throttle movement, particularly in 2300 to 1200 rpm range. 3000 and above vacuum continues to increase to 18 or so at 4000 rpm. At which point I’m thinking that the secondary’s are beginning to open under any acceleration.

[quote]Drop to 54's, stick a PV about 2" lower than cruise vacuum, and stick with Orange. Unless you have a big bump in displacement and compression, go with screw position #1. 10:1 go with #2. I run the highest numeric number possible. With the 10.5 I was pulling nearly 24 mpg with the Holley. I pull about 20 with the Carter. But then I run short gears now, and can't keep my foot out of it. [/quote]


Your proposal to step up to higher PV, say 6.5 or 8.5, and going to a smaller jet is interesting. Correct me if I’m wrong here, but wouldn’t I be dipping into the power valve almost every time the throttle was depressed the slightest due to my crappy vacuum readings? Or rather running rich / lean continuously. I’m willing to try anything.

Were you running the Holley with today’s 10% ethanol mixture, or good old gasoline?

Bill

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67' Dart GT Convertible; the old Chrysler Corp.
82' LeBaron Convertible; the new Chrysler Corp
07' 300 C AWD; Now by Fiat, the old new Chrysler LLC

The cam is outside it's power band at this range and is having problems coping on the lower side...looking at the numbers if you start to gain vaccuum at 3000-5000 with the pedal almost to the floor...that is where the cam is needing to operate...Sadly, that means the car with this combo is race track only...instead of spending the time and money trying to make the carb attempt to keep the cam happy, I'd pull the cam and put in something like a Erson 270/270 with 109-110 degrees of LSA...it will idle better, get better mileage (better vacc/signal at all ranges) and should provide a nice wide power band that will provide driveability at 800-2300...but allow you to grab some good track time at 3-5000...

(Most performance guys in my area know if the cam is too hot, you have to set the idle by what makes the cam happy- 1000-1200 idle rpm, not by what the factory manual says...)

-D.Idiot

CJ,

How far above sea level are you operating your car? Most of my driving is 1000 feet or less.



DI:
[quote](Most performance guys in my area know if the cam is too hot, you have to set the idle by what makes the cam happy- 1000-1200 idle rpm, not by what the factory manual says...)[/quote]

Ah, that cam again. It dose smooth out at 1000-1200 rpm, and pull 12 inches Hg at that point, and is real lumpy in gear at 600-700 rpm. I can get it to idle down to 500 rpm firing randomly, but often stalls when coming to a stop at that setting if not two footing it or shifting into “Nâ€￾ at last minute letting idle rebound to 1000+ rpm.

[img]http://i294.photobucket.com/albums/mm87/wjajr/Dart%20Engine/100_1373.jpg[/img]

Hard to see from this visual aid:

Exhaust:
At 0.006â€￾ lift = 314 degrees -- total lift at lifter = 324â€￾ at 113 degrees
At 0.050â€￾ lift = 236 degrees

Intake:
At 0.006â€￾ lift = 315 degrees -- total lift at lifter = 321â€￾ at 99 degrees
At 0.050â€￾ lift = 235 degrees

We were discussing a camshaft change last winter for this drivability and tuning issue. I was not able to locate an engine puller to use, and did not want to purchase one so that project drifted off into limbo.

So I guess what I need to do is get an engine puller & stand, as I also need to dig into the transmission as well this winter to cure a 2-3 flair-up and converter drain-back problem. It will be a lot easer to yank the whole shoot’en match out in one pull rather than trying to mess around pulling the transmission, and installing a cam with block sitting in engine compartment.

With engine out I can conduct some needed metal & paint work on lower fire wall, K frame, and fix all oil leaks. Also perhaps bump up compression to 10:1 if new cam will allow it while everything is apart.

Bill

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67' Dart GT Convertible; the old Chrysler Corp.
82' LeBaron Convertible; the new Chrysler Corp
07' 300 C AWD; Now by Fiat, the old new Chrysler LLC

Somewhere around 340' altitude in this area.

I forgot about your cam. Still, if your cruising at 15ish Inches of HG, then a 10.5 will benefit your build. It's going to enrich at idle though.

That cam is going to have you chasing your tail. I agree with DusterIdiot. Too much to get good street results.

With the OCG #34, I have ~9" HG at idle. Cruise is a solid 15. I've got the biggest springs they sell on my metering rods. Getting right around 20 mpg, but that's pretty subjective with the fuel cell, and no standard fueling regimen.

CJ

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Part of Tyrde-Browne Racing

CJ:
Glad to see I’m close to your level in the world…

I’m battling rich at idle now that often produces back spin at engine shut down if I don’t let the engine return to park idle of 1000+ rpm first.


I’m going to need to select a cam profile, something that will produce low & mid range grunt, but still spin to 5000 rpm or higher. I need to have a few thousand rpm over 3000 which is 60 mph with 3.55:1 rear and current tire size so I can have some head room to pass, and get some use out of second gear.


Also what ever cam I select has to be compatible with higher compression ratios 9.5;1 on up to 9.9:1. By replacing present fel-pro head gasket with stock steel gasket I can get to 9.9: 1. I might as well take advantage, if possible, of highest compression ratio easily available to my build.

Bill

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67' Dart GT Convertible; the old Chrysler Corp.
82' LeBaron Convertible; the new Chrysler Corp
07' 300 C AWD; Now by Fiat, the old new Chrysler LLC

Low and midrange, power to 5000. For the Erson RV15M compression is a bit high, but I ran the RDP version at 11:1. Power was dropping off at 5k. Gobs of power at 3000, 3500.

An Erson 270 should work pretty well too. A bit more up top. With your gears, it should work well.

2¢

CJ

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Part of Tyrde-Browne Racing

Big problem I can see is that you're trying to idle a modded motor near stock idle speed. Don't bother. I would set it at 900 in N, and it'll drop to 800 or so in gear. Then you can get your PV/jets closer to right. Don't worry about clunk into gear, if any. You can do that for decades w/ no damage (been there).

Lou

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Home of Slant6-powered fun machines since 1988