bought a intake and carb package deal for my slant in a 40 project. turns out the 390 is actually a 600! can't buy a 390 right now. any suggestions on primary jetting for a starting point. it currently has #69's in it.

Start the primaries at #62 or 63s and work from there.

-D.Idiot

thanks for the starting point. forgot to mention that i have the mopar purple cam in there, so i think i'll try the 63's
or am i wasting my time , and should bite the bullet and find a good used 390. i can rebuild them.
Chuck

How much compression, what transmission, and what gears are you running?
Head work? Exhaust?

A street build a 390 will work pretty well on. A track build, a 600 might be in order.

I've run both. Gave them up for a Carter and no more headaches.


CJ

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Part of Tyrde-Browne Racing

don't know a lot about the enginr build. it is a used repossed one that came out of a bracket car. it had a auto behind it. i am putting in my 40 plymouth, as a driver car. i have had all the high horsepower stuff, and am getting to the point in my life that i don't really care about the h.p., but i still like to do a burnout at times and run through the gears.
it is getting a a833 overdrive 4 speed, and i have a 83/4 3:50 rearend in the car. it has had some ameture head porting. don't know the compression, but all cylinders checked near 150# before i did a valve job.
at this time, i'm going to run a single 21/4 exhaust. and as i said it has the mopar purple cam.
thanks for your intrest
my main objective is just to have fun with the car andbe a little different than all the sbc's out there, and to be able to run down the highway all day at 75-80..
Chu

Save yourself a lot of grief, install an Edelbrock Performer 500 CFM. It'll work right out of the box.
Without knowing the specifics of the engine, it's tough to say how the Holley will act. Generally, the circuits will have to be played with to get a Holley to work right. It can be done, but it takes a lot of farting around.

CJ

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Part of Tyrde-Browne Racing

thanks for the tip. i have had great luck with the edlebrocks in the past, but mostly on v-8's. i wqas thinking that 500 may be a little big for a six banger. i know they are a little forgiving due to the vacuum secondaries
thanks again.
Chuck

CJ:
Official Holley Farting around Department:

I have a slightly modified engine, over sized valves, porting, 9.5 cr, hot cam, Clifford 4V intake & headers, and a Holley 390 perched on top of this pile of parts. This car was built to drag race in the early nineties, and will crank to 6000 rpm in a flash.

I have been farting around with this carburetor since getting the car in March of ‘08, and still haven’t got it right. It is close, take-off bog is long gone, smooth transition into secondary’s, choke now works, secondary opening rate has been changed a hundred times, and fuel mileage depending on jetting is 10 to 18 mpg. This carburetor dose not like the low idle vacuum of the big loping cam as the power valve will open & close at idle in gear when at a light. I can tune for drag racing ~ performance, or street mpg ~ no performance, but no in between. LOL

So now I have decided to install an Edlebrock Performer along with a yet undetermined torque cam, and be done with the whole uppity mess. That will be next winter’s project.

My $ 0.02

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

yea bill,
the edlebrock seems to be a favorite by most. the reason i am trying the holley is because i already have it, and i have worked with holleys for years, and have a lot of parts around. if i get some extra cash, i think i'll step up to the 500 edlebrock. it may have some jetting issues too as it is a little large for the slant, and i have no parts around for those. may work good right out of the box though. worth a try.
Chuck

[quote]the reason i am trying the holley is because i already have it,[/quote]

Copy that Chuck.

A 390 was there, it sort of worked, therefore it is… Sometimes it doesn’t pay to be a cheap bastard. LOL…

Sun rises over Marblehead Department:
A little North Shore humor there…

However, I must admit that I have learned a lot about how a Holley carburetor works, and how to tune it. This knowledge is some what transferable to other air fuel mixing devices.

The problem with my carburetor is I have been trying to make it perform in a way my build won’t allow it to work as designed. The biggest hiccup is; too low and vacillating vacuum signal at idle, and an automatic transmission.

It took a long time before I realized that the power valve was pulsating on & off in perfect harmony with the vacuum needle’s wild swings producing a syncopated rich condition. Poor vacuum signal makes tuning idle mixture imposable, creates run-on or back spin after engine shut-down, and caused real crappy fuel mileage in town. But hey, it sounds real cool, like a camed up 340.

A.D.D. tangent:
At car shows when driving in, often some guy will ask; “is that a 340 four barrel?â€￾ (like that is something special)

“Your half rightâ€￾, and than I won’t open the hood until clean-up prep, and registration is completed, about a half hour or so… LOL

Later; “I thought you said this was a 340???â€￾ Love it, just love it when they say that. LOL

Back on task:
If I understand correctly, the Edlebrock performer has tapered rods that control air/fuel mixture, and no vacuum controlled power valves, not unlike an SU carburetor. This is why they must work well with a camed up engine that produces goofy vacuum signals.

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

I've enjoyed my holley and now my demon as for the big cam motor that was what my old motor was you could change your pv to a lower number and up the pump shot to compensate if need be. I worked around the vac signal on the old motor seemed to do the trick.

Kev

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kev,
that's quite the plumbing exercise on the exhaust of that one, and that demon looks real good on there.
bill,
actually from my little experence with the carters and edlebrocks, they DO depend on vacuum signal to raise and lower the metering rods in the jets, but it may not affect the idle like a opening power valve would.
actually the engine i put in the 40 is just temporary. just want to get everything sorted out with this temporary engine, and while i am driving it over the next couple years, i want to build a new motor. will have the 198 crank, and the long rods for starters. from there, i don't know yet. not good at planning that far into the future.
i just love doing something different.
if i was looking for a lot of power, i would have gone hemi, but those days are behind me at this time. just love my old cars, and doing things that they say you can'y do.
the firewall work was extensive to get that slant in that engine bay. firewall set back 6" on the passenget side. but a lotof room for steering linkage on the drivers side. also have to build a alternator bracket to put it on the drivers side yet. maybe this weekend.
Chuck

I second the starting with 62s and I would go 68 on the secondaries.

[quote]actually from my little experience with the carters and edlebrocks, they DO depend on vacuum signal to raise and lower the metering rods in the jets,[/quote]


Chuck, I figured the rods move on vacuum as dose the rod in an SU, but they are dampened where Holley’s PV is on-off once the pre set vacuum rating is crossed. So what happens is the darn things can open & close rather quickly in comparison to a rod metering set-up.

As for trying lower rated power valves, I have: “The Plugâ€￾; 1.0; 2.5; 3.5; 6.5; and an 8.5. Currently living with a 2.5, and plugged "drill holes" in throttle plates. The Plug did clean up idle, but had to go up six jet sizes to get any drivability, and no punch under WOT. I have been on the phone with Holley, their solutions were not so hot.

I shall keep the 2.5 PV, reinstate the 3/23â€￾ throttle plate drill holes, and hook up the O2 sensor just purchased, and see where I’m at for mixture.

I think the 390 carburetor would work rather well on an engine generating a rock solid 10â€￾ Hg at in gear idle. I have 0-6â€￾ at in gear loping idle of 600 rpm, and 8-10â€￾Hg at 1100 rpm in “Nâ€￾. It sounds real cool, but sucks to live with.

Like I said, it is time to pull the old school cam for something that produces a stronger steadier idle vacuum signal now that this car is no longer drag racing every weekend.

_________________
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