Hey fellows slanters, ive been muddling with this 84 ram engine build tuning for quite some time now. I think i'm nearly sort of dialed in but i'm still not quite there.

Getting a bog on acceleration and a run on when turning it off only with the vacuum can hooked up

and im running too rich at deq

84 ram pickup 4000 lbs
hydro 225 auto stock tq stall 3:23 rear on 215 70 15 tires about 25.7"


Over .030 fresh build
9.5 to 1 compression
.170 valves
Supposedly blended ports
dad truck rdp cam from this site, like a 252 s i believe. Oregon cam grinding provided
all assembled by Portland Engine Rebuilders
offy intake
holley 390 carb ( new )
Hooker 6 into 1 header 2.5" single exhaust flow through stainless cat then 2.25 after low restriction flow master style muffler
hei ignition

Ok so i have the sam provided distributor spring kit I belive im using the green ones right now
timing initial is 12*
Mech is 35* all in at 2500
Vacuum takes it up to 43*
I have greatly retarded vac because i thought it was pinging but it turned out to be loose eng to trans bracket bolts rattling

For the Carbie

i'm back to 51 jets. it loves it there
pv is 8.5, it hates 6.5
nozzles are 28, hates 31
i have the pump cam kit but that is still stock orange I think on pos 1

the stiffest spring is on the secondaries to keep them closed till i get primaries dialed in

Well waddya think, it seems to run the best here

but it aint happy yet.

fuel mileage about 15. was wanting to see it closer to 20

exhaust is still a sooty black

The anticipated goal is to run my little pu at 20 mpg unloaded then when loaded with an additional 1000 lbs to be able to pass the semis going over Mt. Ashland. That's the most aggressive Oregon climb over I-5 for those from out of state.

Thx for your help, Ray

Engine specs are

Head n gasket have a compressed volume of 74.5 cc
with an engine swept vol of 624.6 cc and static is 699.1 cc
with a static cr 9.384 to 1

int. uses grind no. 1333 int which is 212 @ .050, 256 @ .006, and .298 lift with a 110* lobe separation and a 106* lobe center total lift is .447


exh uses grind no. 1527 int which is
oregon cam grind no.s
for anyone who knows how to operate cam design specs

From what most people say, 28-30 is the max mechanical advance that the slant 6 likes. May give a little initial a try and see how it likes it.

_________________
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

I struggled with the same a few years ago. I think you have too much of transition slot exposed.

Back off on the idle speed screw enough so that only a square of the transition slot is showing when throttle plates are closed.

Make sure you are not getting any mechanical advance at idle and a few hundred RPM above, and set idle speed by advancing or retarding timing.

Re set idle fuel mixture.

After all of the above is set, one will most likely have to play with the timing some more to get correct rpm, and back to idle mixture screws, and back and forth until idle circuit is leaned out, idle rpm is good.

Use a vacuum gage to help with the tune try to get highest reading. The closer to perfect tune the higher the vacuum should be.

Run-on is a result of too much fuel & air and timing advance available at shut down, fix it, and that bog will go away. You may find that dropping back to a 6.5 power valve will work fine once the idle circuit is tuned

Now dial in accelerator shot duration and volume.


It is important that all mechanical timing returns zero at idle every time. I recurved my distributor so no mechanical advance kicked in before 300 rpm over idle rpm. (It has a big overlap cam, 1100 rpm idle) Once any mechanical advance is removed from idle rpm range, and air & fuel reduced by closing up transition slot leaned out idle mixture, the engine stopped the running backwards at shut-down crap 95% of the time.

Also once idle is correct, throttle plates closed down to correct stop, the ported vacuum will drop to zero at idle stopping any vacuum advance.

Get a copy of the following books: "Super Tuning and Modifying Holley Carburetors" by Dave Emanuel; and "Holley Carburetor Handbook 4150 & 4160 Selection, Tuning, and Repair" by Mike Urich. Those two guys, and a few here on the forum got me out of the weeds with my 390...

_________________
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

Thx Rick,

I dialed out the timing curve at various movements n rpms

with the timing dialed back some.

set initial at 7 cause it seemed to be where max was to be at 30, even though it is an unmolested 9r advance slot.

this measuring had it like so with no vac adv

Rpm timing vacuum no load


900 7 16.5

1600 10 19.5

1800 14 20

2000 20.5 20.5

2300 24.7 21

2500 25.9 21

This is now max mech adv. but the mark sometimes wiggles + or - 1 degree on crank pulley.

ran it. pulled strongest yet through all the fears with nice upshifts at 45 and 65.


Thinking ok why not try 10 deg initial. drove it, was not so strong but drove ok

got back home, it had creeped to 10.5 ini ???

moved it to 9 and the running was improved enogh to think ok this is good.

so I decided to map the curve again and the damned thing was back at 10.5 btdc.

WTF?

Ive been through this dist. a number of times looking for slop or loseness in the springs or top plate or shaft. none ever visually appears.

I must say it is hard to get a base point when the mechanical timing won't stabilize.


I did also notice that i was able to turn the idle mixture screw in 1/2 turn for slightly improved vacuum, so that was reassuring.


So for now I'm going to dial the vacuum adv to where it does not oing and try deq again.


I have been following the Urich manual from long before the start of this project, I have not seen the other one listed. Thank you for the tips.

Keep em coming please,

Ray

Ok, that's good enough for today.

Vac can 5 turns out
initial timing at 8 and 950 rpm idle

no run on

good torquie feel

Almost crisp upshift at 65.

will try deq tomorrow and then go from there.

Not quite there but closer

Thanks guys

Hi rob, Thx for getting back

I don't have an af meter per say, what I have is a standard o2 installed in the head pipe. Been reading it with a multi meter.

Also since it's been installed the idle screw has been as far out as I dare so it won't fall out.

Idle adjustment is at the mercy of the other parameters.

I use an o2 sensor as well. I find that idle mixture screws become very sensitive the closer to ideal mixture. 1/8 turn will upset mix. I also use a volt meter to adjust idle mixture, a dash mounted gage while under way just to see what's going on. Said sensor is mounted just aft of header collector about 30 inches from head.

If your o2 sensor is not heated, or has less than three wires, idle mixture readings can be off. That sensor has to be above 600 or so degrees F to produce a signal, and if it is not heated one can get goofy to no voltages.

_________________
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

Nice WJ,

Im trying now to make my adjustments at idle using the 02 sensor and voltmeter.

I'm at idle only now. 9.4 btdc, 980 rpm, 17 lbs vacuum, .273 vdc on 02 sensor

Im getting a 0.3 vdc at idle with the settings last reported which indicates a slight lean condition.

An oxygen sensor will typically generate up to about 0.9 volts when the fuel mixture is rich and there is little unburned oxygen in the exhaust. When the mixture is lean, the sensor's output voltage will drop down to about 0.1 volts. When the air/fuel mixture is balanced or at the equilibrium point of about 14.7 to 1, the sensor will read around 0.45 volts. - from web sources

While DEQ is measured at idle and shows an extremely rich condition and my exhaust pipe color is still black, but getting less sooty looking.

I'm just scratching my head with this now

Just trying to get my fuel mixture straight and get deq to agree.

So, I went through 5x yesterday (turns out to be the daily max allowed )

With 51 Jets it took getting the initial timing up to 18 before the the richness reading at deq began to drop off. Thinking this is way too much timing, I dropped the Jets to 49 and put the 6.5 power valve back in.

This helped o2 reading on my meter, though still a little high. Deq numbers were back to crazy.

So after backing the timing to 14, my reading is now at a perfect 14.7, yah

but deq still shows me as Rich.

Now with the pv at 6.5, it's stumbling. And it seems happier wth the more advanced timing, but I also get a slight ping

I know I will need to step up the acc pump cam at some point, but I'm really thinking dad truck is right about my cam timing being off.

it always is really powerful from take off, except for now. . .

But then drops off after shifting into 3rd.


thoughts?

Is the O2 sensor heated?

Single wire O2 sensors may lose enough heat at idle so that they don't read correctly..........

_________________
Ed
64 Valiant 225 / 904 / 42:1 manual steering / 9" drum brakes

Interesting point, about the single wire o2 sensor.

It will appear to have cleaned up the fuel issue for the first 5 min following a change in tuning. Then show the more accurate setting

A straight forward no nonsense sink you teeth into step by step tuning guide for the holley 390 by the guy who knows.


David Vizard's How to Super Tune and Modify Holley Carburetors, David Vizard.
https://play.google.com/store/books/det ... E30rLFql0C

You gotta make to chapter 12 to get through all the asides and technical mumbo jumbo, but this is the best I've seen yet.

Thx Mr Vizard.

Stumble or flat spot off steady throttle often is a result of too lean main jet. If you can extend VOM probe leads enough to be able to read mixture while driving, discerning mixture through each stage, idle, transition, main jet, and enrichment by PV, will be easy to see.

I suspect 49 jet is too lean when running on main jet and throttle plates are opened mixture become excessively lean before accelerator pump shot can take up the slack, and before power valve steps in due to maintaining high enough vacuum to keep it closed during light acceleration.
Power valve is selected by vacuum levels at idle, per Holley, and main jet selection here.

8007 or 390 cfm carburetor uses vacuum activated secondary metering block, not jets, so tuning secondary circuit is a different kettle of fish than what is shown in video. Larger CFM and mechanically operated secondary Holley 4 barrel units use secondary jets.

_________________
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

Thx W

In sure you're right about to lean. I've got 47 in there now but it doesn't stumble if I feather it through the transition phase.
Been muddling through with a narrow band 02 n volt meter. Just not cutting it.

Buying a wide band setup today.

Tired of floundering.

Got my isle setup Where I'm happy with it till I'm good with my cruise n wot settings them I'll go back look at timing curve again

using initial at 10 bdtc for now

Thx for you help n support

Ray