Load-0-Matic issues.....still

[NC-Fordguy]

Hopefully you all can help isolate the problem. I am at my wits in and I'm thinking a V-8 swap is in order as this is where my background is.

I have a 66 bronco with a 170. The truck has 89k original miles. The past six years it only had 30 miles put on it. I got a good deal I thought and bought it.

Problem now is the truck dies under load when warmed up unless I pull the choke or put the truck into low range.

I have rebuilt the carb(autolite model)
Complete tune up(plugs, wires, points, condensor rotor and distrubuter cap)
Repaired the vacume leak at the distrubuter(stripped brass nut on the vacume line)
Eliminated all vacume leaks
Tried various timing abjustment anywhere from 0-12 degrees BTC

When warm vacume reads at idle 18 inches of vacume with only a slight flicker

With vacume guage in line between the carb and distributer the vacume will get up to about 5 inches under acceleration and the truck dies.

Any ideas where the problem is???

 

[fordconvert]

6 years and 30 miles? Whats the fuel like? Have you tried hooking a vacuum pump/gauge to the distributor and making sure its holding vacuum and its all moving inside? Checked the dwell with a dwell meter?

 

[NC-Fordguy]

Fuel Lines and tank are good. Blew out the lines to get any junk out. New gas in tank. Replaced filter at carb

I don't think this is a fuel delivery problem as the truck will run in low range. It's when it is hi range the dieing occurs.

Don't have a dwell meter but the springs in the distributer look good and did the old redneck test on creating vacume to the distributer. The diaphram seems to be working???

My thinking on this, there is someting wrong in the distributer...maybee a weak diaphram, spings, or plates.

I read the sticky posted on the load-o-matic to gain an understanding.

I do wonder how the vacume signal works on this sort of system though??? As I posted earlier the truck will only get about 5 inches of vacume before it dies out and that's at 2k rpms. Seems like it should get more thru to advance the distributer

 

[fordconvert]

Just looking at a few of the specs for the load o in the 66 manual looks like the around 12* at 4" of vacuum is all they are supposed to have so that 5 you read may be correct. Also explains why hooking a regular mech/vac dizzy to the scv port does not work since the regular ones are expecting 15+ to get full advance.

 

[LEROY POLL]

TJH

.....THE VACUUM WILL BE HIGH ALL THE TIME IF IT IS A LOAD-A-MATIC DISSY. THE ONLY TIME IF FALL IS WHEN YOU HAVE WIDE OPEN THRODLE. THEN IT WILL DROP TO ABOUT 2* ABOVE YOUR SET TIMING. AT IDLE THEIR IS LITTLE TO NO VACUUM TO THE DIST. WHEN YOU CRACK OPEN THE THRODLE AT OFF IDLE YOU SHOULD SEE FULL VACUUM... ABOUT 20 IN LBS OR MORE. IT CAN GO TO 25 IN LBS. IF IT IS LOWER THAN THIS YOU HAVE SOME KIND OF LEAK. TEST AT ABOUT 1200 RPM.

.....THE MOST POSSIBLE PLACE TO LOOK IS THE DIAAPHRAM ON THE DIST. THEY GET A SLOW LEAK THAT GROW TO A BIG LEAKS.

.....YOU SAID YOU HAVE 18 INS AND IT GOES UP TO 5 INS.???? DO YOU MEAN IT GOES DOWN TO 5 IN.?

.....IF YOU PULL THE CHOKE AND IT WILL RUN..... YOU ARE TOO LEAN. VACUUM WILL CAUSE THIS ALSO. LOOK AT ALL VACUUM LINES OFF THE MOTOR. EVEN TO THE TRANNY, WINDSHIELD WIPERS. AND CONTROLS. CHECK TO SEE IF THE CARB. NUT HAVE LOOSENED UP ALITTLE.

.....IF YOU HAVE ANOTHER CARB. CHANGE IT OUT AND YOU CAN TELL IF IT IS THE DIST OR NOT.

....STAY WITH IT YOU CAN GET IT DONE.

LIVE IN GRACE

LEROY POLL

 

[LEROY POLL]

SORRY TJH I WANT TO SAY FORDGUY

LIVE IN GRACE

LEROY POLL

 

[lilgoomba]

I would look into the possibility of vapor lock. The original six cylinder fuel lines were small enough to be brake lines in most cases.

 

[NC-Fordguy]

Let me clarify this a bit.....

I have 18 inches of engine vacume. This reading is pulled from the fuel pump(vacume fuel pump to run the vacume wipers) This leads me to beleive I have a good engine with no internal issues.

When I place a T fitting(so I can get a vacume read) in the line between the distrubuter and carb at idle it reads zero, when accelerating the engine, it gets up to about 5 inches of vacume, then dies. This happens around 2k rpms.

I am poitive there are no vacume leaks as I have replace any line or hose that was suspect. I've gone through 2 cans of carb cleaner trying to find more leaks and can not find any more

I'm finding this conflicting on the replies.....

Is 5 inches of vacume normal for this set-up or does it need more??

As far as swapping another like carb...don't have one nor know where to find one

The fuel line is rather large, I'd say 3/8 metal tube and it has been blown out to ensure there is no trash in the line since the truck sat up so long

 

[66 Fastback]

I have not seen where you posted the specific carburetor model and whether or not it has the SCV (Spark Control Valve).
Was it replaced during the rebuild?

You might also want to check the harmonic balancer to make sure that it has not slipped. Make sure that the engine is really at TDC #1 compression stroke when the balancer indicates it is there. Your 12 deg of initial timing may not really be at 12 deg unless this is verified.

Add on..
A slipped balancer and improper ignition timing would also lead to low vacuum readings.
Doug

 

[fordconvert]

Leroy, are you sure about those numbers? I just read the stickies and my 66 book an it does not give numbers anywhere other than the ignition specifications section. All the text mentions full 'manifold vac' but then goes on to talk about how its all limited by restrictions and the scv valve. In the spec section there are 3 dizzys that appear to be load o's (out of 20 some) and all 3 of them list a maximum vacuum as 4" for full advance of 12*. Am I reading things improperly? I could have easily missed something.

I still have the 1100 on my car, I suppose if I have time later I can tape a vacuum gauge to the windshield and go for a drive.

After reading all that crap about the Load O it does not seem much different than a plain old 'ported' source on any other carb, unless it does indeed operate at much lower vacuum levels.

Doug has a good point about the timing marks. Have you tried setting timing with a vac gauge and not looking at the marks? May be worth a try since its easier than trying to verify marks on a complete motor in a car.

Another thought, does the carb still have its nice smooth venturi insert in it? If you look down the throat it should be a darker color than the aluminum and a nice (fairly small) smooth curve all the way down. If you look down there and see aluminum and a brass nipple sticking in there someone removed the venturi insert and they sure dont run right with that missing. The one I have the guy removed it because it was a restriction and told me the car ran faster without it (except for it was hard to start and stalled all the time). Others told me that sometimes they caught fire and melted so people just took them out.

 

[NC-Fordguy]

Autolite 1100/1100-1 model carb

SCV replaced during rebuild

When I bought the truck it was extremely hard to start and the carb leaked gas at several places, hence the re-rebuild

The truck now starts fine...even purrs at idle with no miss. It's the dieing under load that is driving me nuts

Have set timing using both a vacume guage and timing light

When I get home tonight I'll look into the venturi throat

 

[66 Fastback]

all 3 of them list a maximum vacuum as 4" for full advance of 12*. Am I reading things improperly?

I would interpret that to mean that to mean when there is 4" or more of vacuum, the advance would be fully advanced at 12 deg. It would not imply that the engine is only developing 4" of vacuum or that it is only sending 4" of vacuum signal down the vacuum line to the distributor.
Doug

 

[kirkallen143]

I will add that I had the same problem twice on my '73 bronco with a 200. The first was the fuel level was too low on my Carter YF carb and the second was a dirty/rusty fuel tank stopping up fuel filters. You will have to pull the back original bumper to get to the tank.

It could also be not enough fuel pressure, had that happen, too (ran great at idle, but died out while under load).

Kirk

 

[NC-Fordguy]

Took the carb off the truck, must have been about the 10th time thus far.......

Venturi insert is still there


I don't think this is a fuel delivery issue as the truck will run at road speed with the choke partially closed, or when the truck is placed in low range.

I could get a brass tee and install a fuel pressure guage inline and see what it's getting????

It seems to me the big question here is how much vacume should there be between the carb and distributer. Is it the around 5 inches as posted by one member or the 15 plus inches posted by another. According to my nearby napa jobber, a reman distributer is available. I'd just hate to spend the money on a new distributer only to find out it does not solve the problem

If any of you have the same set-up it would be so helpful if you could
enlighten me.


On a side note, I stopped by a junkyard to pick up and item for a friend and just happened to ask the guy if he had any late model inline six cars laying around. He took me to a 83 mustang with all the goodies still under the hood. I can take the carb, wires, distributer, controller, harness, etc for 50 dollars....Get's me to thinking.......

 

[fordconvert]

Work sort of got in the way of playing today so I did not have time to go throw a gauge on the 1100 and see what it does. Tomorrow looks pretty full also but I will try and get to it if no one else can verify the numbers by then.

 

[Frankenstang]

Problem now is the truck dies under load when warmed up unless I pull the choke or put the truck into low range.

I have rebuilt the carb(autolite model)

Not to jump on this one symptom, but this may be why others have suggested a fuel issue.

I've never known a timing issue that could be overcome with choke adjustment.
Are you sure you have the float set right? Did you change the accelorator pump on the carb (and make sure all the check balls and the weight went back in place)?
Cutting back the air with the choke (too much air) would seem to suggest too little fuel in the ratio.

 

[Frankenstang]

Edit: Dang double post

But while I'm editing, the slipping harmonic balancer on these sixes is alot more common than you would think, as mentioned. I like to set the timing by advancing till she starts tapping, then retard just a bit.

 

[NC-Fordguy]

I'll get an adapter this weekend to install a fuel pressure guage and see what happens


If anything the float is set to high. It's something that I know I need to set down some especially seeing how this truck will see some off roading.

New accelerator pump installed and new check balls installed from the rebuild kit

I've played with the mixture screw, setting it 1 and a half turns out according to the re-build instructions and have turned in nearly all the way out without any improvement

What I do wonder is the truck will run when warm, in low range without the choke being pulled. So if this a fuel issue wouldn't the truck die out in low range as well???

I do wish to ditch the vacume fuel pump(if I don't become totally frustrated with this and drop in a V-8) and go to either an electric or mechanical pump. Will the cam have a lobe on it to run a mechanical pump???

 

[LEROY POLL]

HELLO


FORDCONVERT

.....THE VACUUM IS COMING OFF THE MANIFLOD VAC. SO WILL RUN HIGH. MOSTLY THE L.O.M. WORKS VERY WELL ACCEPT FOR W.O.T. AT WIDE OPEN THRODLE (W.O.T.) THEIR IS VERY LITTLE VAC..... MOST PEOPLE DON'T GO TO W.O.T. WHEN THEY DRIVE. ( I KNOW, I KNOW WE DO IT ALOT.) BUT MOST PEOPLE NEVER GO MORE THEN HALF WAY. SO THE L.O.M. WILL BE JUST FINE. FOR RACING IT WILL NOT GIVE EVERYTHING YOU WANT. SO THEY ARE UPGRADED TO BETTER DISTBRITORS.

.....THE L.O.M. WORKS ON THE PRINCIPLE OF TRACKING THE VAC. MOVEMENT. SO THEY OVER ADVANCE THE DIST. JUST OFF IDLE AND AS MORE GAS IS GIVEN THE VACUUM WILL DROP TO WHERE THE ADVANCE IS NEEDED. AS RPM GO UP SO DOES THE ADACNCE.

..... THE SPRINGS ARE THE ONLY THING KEEPING THE MOTOR FROM HAVING FULL ADVANCE ALL THE TIME. THE VACUUM IS STRONG ENOUGH TO PULL THE TIMING ADVANCE TO FULL ADVANCE. BUT FORD USES THE VACUUM TO TRACK YOUR FOOT AS IT STARTS TO DRIVE AWAY. STEP ON THE GAS AND VACUUM FALLS...ADVANCE FALLS. AS MOTOR GO BACK TO FULL VACUUM THE ADVANCE GOES BACK TO FULL ADVANCE.

.....THEIR IS MORE TO IT THAN THAT BUT YOU CAN SEE IT WORKS VERY WELL. I HAVE WRITTEN ON THIS FOUR OR FIVE TIMES ON THIS SO YOU CAN LOOK UP SOME OF MY POSTS.

.....IN MY DAYS GROWING UP ...ALL FORD HAD SOMETHING LIKE THIS. MY FATHERS 1954 FORD V8 HAD THIS AND THE SHOP I TOOK IT TO FOR A TUNEUP SHOWED ME ON THE MACHINE HOW IT WORKED. I DIDN'T REALLY UNDERSTAND ...BUT IT SURE RAN MUCH BETTER AFTER HE DIALED IN THE L.O.M. DIST.

.....I BELIEVE I CAN TUNE MOST OF OUR SIXES WITH THE L.O.M. DIST TO WHERE MOST PEOPLE HERE WOULD LIVE WITH IT AND LIKE IT. I'VE DONE IT FOR MY FRIENDS AND THEY CAN'T BELIEVE HOW MUCH BETTER IT RUNS.

FORDGUY.

.....IF YOU HAVE THE SPRING ONLY DIST. ...THEN YOU WILL NEED UP TO 15" OF VAC. TO THE DIST. TO HAVE IT ADVANCE. ALSO YOU NEED TO HAVE 10* WHEN TIMING AND NO VAC.

.....FORDGUY IF YOU WANT TO E-MAIL ME FOR MORE I WOULD BE GLAD TO HELP YOU.

LIVE IN GRACE

LEROY POLL

 

[NC-Fordguy]

Getting about 5 psi of fuel pressure so I am assuming this is correct???


Seeing how I can not get a consensus of diagnosis I'm wondering something else.........

If I install a DUI distributer that does not require vacume to advance, this should reslove the issue???