Most of today was burnt fiddling with the 390 Holley. Make a change; go for a test drive, over and over until a noticeable performance improvement could be felt.

Once again I am attempting to lean out < 2800 rpm steady cruse to get the A/F gage out of the rich zone. No end to various combinations of transition slot exposure, secondary idle circuit butterfly stop adjustments, and idle mixture screw turning. Oh, the throttle plates got drilled & filled several times as well. All this screwing around took place after some interesting, but not to informative, carburetor chatter with Holley’s tech line. I did finally get a rule of thumb for how much transition slot should be exposed; open throttle plates just enough to expose a square hole at the slot… This tidbit has been very helpful balancing primary and secondary idle circuits.

During testing I discovered that the secondary throttle plates were not opening under any load conditions or spring combination. This discovery necessitated removing the vacuum diaphragm housing as well as electric choke to get to the problem; blocked vacuum passages by cork gaskets from a rebuild several years ago. Once the passages were opened, the diaphragm started to do its job. Once the cooling vacuum passage to electric choke became opened I found this introduced more air when throttle plates were closed leaning out idle mixture which required one more idle mixture adjustment resulting in higher idle rpm, and an one or two more inches of mercury to 12… a good thing.

So I guess for the last umpteen thousand miles and several years this car has been a camed-up, free flowing, anemic super six, with no low end grunt. Now with a purple spring installed, and close to ideal air fuel mixture this car has come alive. When power braked, it happily spins both rear wheels, and out on the road around 3800 rpm the secondaries open and off she goes. During last test drive I got a first to second chirp at WOT; that is a new trick for this car

Tomorrow I’ll try to drop secondary threshold opening to 3400 rpm, just above 65 mph cruse rpm. I’m going to jet down to 50, and perhaps 49 to try to lean out steady cruse. I still have a bit of a flat spot coming off steady cruse into acceleration so plan is to increase accelerator shot from 28 to 32 or so.

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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

try the tall yellow spring , not the short yellow . i think you will like it over the purple spring in your application. ron

Purple was a starting point based on someone’s writing here a few years ago. I have the long yellow spring installed now, but haven’t driven the car but a few miles since the change. For the short test it seemed to be satisfactory, but I need to drive it a bit more to see if fits my criteria.

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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

Today I finally tamed the old Holley 390 (4160series,list # 0-8007) after countless combinations of engine timing, throttle plate position, jets, power valves, and secondary springs being tried. It took another Holley Carburetor “How to Bookâ€￾; Super tuning and Modifying Holley Carburetors; by Dave Emanuel, Urich’s little red tutorial, several calls to Holley Tech line, and a most helpful Tim at Summit’s tech line.

For any new members out there in slant land I have had a four year long love hate relationship with this carburetor trying to get it to play nice with a rather camed up modified slant that was built to drag race in the early nineties. When I got this car it could barely get out of its own way, would not spin a tire in sand, and had real nasty drivability issues in stop & go traffic.

As of today the car will happily sit and idle in gear at 750 rpm, idle in park at 1150 rpm pulling 13 inches of Hg the highest ever achieved to date, pull 17 inches at 2800 rpm, and over 20 inches off the throttle downhill, and easily spins both rear tires from a stop on clean bare pavement. Once out on the road 99% of any flat spots are gone, A/F ratio gage shows normal mixture under most throttle conditions except flat ground steady cruse where mixture is into rich zone. I can live with this for a while.


During sea trials this morning after the last round of new settings I was passed by a 2005-7 Mustang GT convertible on a back road shortly after turning onto it. He had passed me earlier headed in the opposite direction moments before, reversed direction, and caught up with me at a stop sign. As soon as we were through the right turn after the stop he got by me. Once passed I dropped to first gear planted the right foot hard on the floor, shifted at 6100, repeated the drill for second gear, and he was not leaving me until we hit about 75 mph at which point it was time to back off… We were double the limit and a butt at that point, and driveways were coming into view. The engine pulled right up through transition, power booster, into power valve seamlessly, and at 3700 rpm I could feel the rush of the secondaries opening. It never stopped pulling all the way to 6100 rpm. Maybe the guy that built this engine was telling the truth when he told me he shifted at 6300 during a race… (He also said he blew up five engines before he figured out how build one right). This car has never made power like this since I have had it. I’m happy guy today. LOL

Sunday we, yes Mrs. WJAJR and I are caravanning 80 miles north with 25 or so other convertibles to Greenville, Maine for lunch on the shores of Moosehead Lake at a place called url=http://www.theblackfrog.com/]The Black Frog[/url]. This eatery looks interesting, the ride will be pleasant, traffic free, two lane rural running all the way top down with blue skies, and temps in the low sixties.

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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

Good for you! My relationship has always been Hate Hate with Holleys.

Really glad you got it all figured out. You have a lot more sticktuitivenesss than I do. But get ready to adjust some more, winters coming!!

Rick

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2 Mopars come with Spark plug tubes. One is a world class, racing machine. The other is a 426 CI. boat anchor!

12.70 @ 104.6

Good deal. Looks like you got it... Holley users really have to get both books to get "all" the information Urich and Emmanuel's book.

Now that you got that dialed in, time to find a 600 cfm Holley with vacc secondaries to rebuild over the winter and use it at the drag strip and see "how much more" the engine really has...
He may have to dial the primary jet up a bit and lay off the secondaries (i.e. Plain spring ) for the season...for the most part if it's dialed in right, he just has to adjust the choke thermostat on the side of the carb about 4-5 'clicks' away from the lean arrow and go from there.


Good Job!!!

-D.Idiot

Rick:
[quote]But get ready to adjust some more, winters coming!![/quote]

Says you Mr. C, I just drive it into the basement… er, rather, Man Cave where she stays nice and warm until April, but not unmolested this winter.

Seriously Rick, I was considering pulling engine & transmission to perform a cam change this winter, but now this engine is running so much better I may just pop off the head examine #5 for ring problem while engine is out.

There is a weak exhaust pulse coming from back three, and #5 takes several more engine revolutions to match other cylinder’s pressures when tested. If there is any scoring, hopefully some honing will clean it up enough so I can just replace rings, and not rebore. The rear main seal drips, oil pan weeps (must be a sad one), and the engine needs to be properly painted.

Also I need to get rid of a 2-3 flair-up with new guts, add a part throttle kick down, and make the modification that prevents converter drain back.

The “It never ends Departmentâ€￾:
Oh, I should degrease and paint K Member, lower fire wall needs metal work & paint… What the hell, why not strip and repaint engine compartment while engine is out.

Electric fan, did someone say electric fan conversion?

Then there is a timing chain replacement project on the 2.6 Hemi powered LeBaron that needs to get done this winter.

[quote]Good Job!!!

-D.Idiot[/quote]

Thanks DI.

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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

That's the way do do it! With all your tuning, you should be able to give some great guidance to others trying to tune their Holleys!

Rick

_________________
2 Mopars come with Spark plug tubes. One is a world class, racing machine. The other is a 426 CI. boat anchor!

12.70 @ 104.6

Been looking over your shoulder from afar. Your patient man Bill!
This reminds me of our recurve sessions........glad you got it close enough to enjoy the car. Sounds like a blast to drive.

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Aggressive Ted

http://cid-32f1e50ddb40a03c.photos.live ... %20Swinger


74 Swinger, 9.5 comp 254/.435 lift cam, 904, ram air, electric fans, 2.5" HP2 & FM70 ex, 1920 Holley#56jet, 2.76 8 3/4 Sure-Grip, 26" tires, 25+MPG

Bill,

Before you put that puppy in the man cave for the winter, why not bring it down to Mason Dixon in Oct and race with us. That way you can make sure your tune is right! You could even caravan down with Ron & Aaron Heath from up your way!! That would be a nice ride in October. Whatcha think??

Rick

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2 Mopars come with Spark plug tubes. One is a world class, racing machine. The other is a 426 CI. boat anchor!

12.70 @ 104.6

Thanks for the invite Rick, but a bit too far for a stroll down ¼ mile strip. I plan to hit my local track in a week or so for their fall car show and nostalgia weekend with flag start gassers, etc. for a few time trial runs. I take a Philips screwdriver, timing light, vacuum gage, and secondary springs along.

Hopefully I can locate a few time slips from a few years ago to compare with new times, if not; I may have published some of the old times from several years ago here somewhere.

The convertible cruise Sunday was a nice ride, which the Dart was oldest and generated a lot of interest. Most aggravating was guy leading in a late model Porsche kept slowing down cresting each hill; I didn’t realize just how closely related those things still were to 36 hp. VW Beatles… LOL

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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