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Hats off to you for perseverance. It will eventually pay off !
What didn't you understand about ''leave it as it is'' to do the timing curve ? (Changing springs etc in that OE dizzy is a ball ache!)
Ok, the timing curve indicates a problem at 1,500rpm (which could be causing your acceleration bog), and also indicates that the timing is advancing too slowly.
It's not a bad linear curve, but can be improved.
Lighter springs will make it advance quicker, I.E. Higher advance at each 500rpm intervals.
BUT, I think that the dizzy is tired. I don't know exactly what would make it retard so may degrees at 1500rpms.
The good news is that the timing curve has given you useful feedback.
The bad news is that you went and adjusted the carb at the same time as adjusting the dizzy. Now you don't know exactly what caused the truck to run worse today.
Focus on one thing at a time, and one thing only !!!
Today, in effect, you retarded your timing by 10 degrees by swapping the 15L's to 10L's, and that is probably the power loss you felt.
That said, all of the timing numbers mentioned since the start of this thread are in the ball park, and shouldn't be causing you the crap performance.
18 degrees of vacuum. Was the needle steady or fluctuating ?
Is the engine smooth at idle ?
I don't know the exact detail, but here's an idea :
If the OE dizzy came with points, the points would take 9v when running, and 12v at start up.
An OE resistor wire would be installed to reduce the 12v to 9v when running.
Let's say that wire has 3 ohms resistance. (Purely for illustration)
If the Master Pro Brain replaces the points, what is the minimum ohms for it ?
Let's say it is 2 ohms.
Having a 3 ohm wire will rob the engine of power.
I put an ignitor in my OE dizzy a few years ago, and fitted an MSD blaster coil.
The coil rating is 0.7 ohms and the ignitor stated a minimum of 1.5 ohms.
I fitted an 0.8ohm ballast resistor, with normal wire, and it ran 100%.
But I also fitted a 1.5ohm ballast resistor for pure curiosity. Turd !!
If you understand what I'm getting at, it's a 5 minute job to check it out.
LOL, I couldn't get the OE dizzy to give me a 100% curve, so I gave it away and got a Pertronix dizzy. 'nuf said.
Laterz
only reason why I changed the dizzy for the curve was because I had it out to clean. Figured may as well, because I knew the curve was jacked up as it was. I tried another plan. Stuffed the lightest springs I had in it. No change in the curve. No change in power. Got home, stuffed the 15L slot into it with the 2 light springs again. The curve changed. Currently though, the advance only starts to kick in arundel 1500rpms. Just doesn't make any sense. Power is better though, as you can definitely feel it kick in. Won't touch the tires, but is better than before.
When we had it apart, the dizzy looked okay internally. No excessive movement in the shaft both up and down and side to side. Cleaned everything out, lubed it all back up, all good. Advance still only kicks in at 1500rpms.
Bog at WOT is a bit better. Because I got plenty of power in the primaries, I'll increase the jet size in the secondaries and update back.
Also. 9v running at the coil. Looks good to me. The original dizzy and ignition setup is duraspark. The motor is running decently at idle, just a slight shimmy from time to time. Vacuum gauge is now dead on at 18" of vacuum. No needle movements.
To be clear, my set up is as following:
15L slot
8* initial timing
vacuum advance turned all the way in
1405 stock tune with .101 secondaries
EDIT. Just got home from a drive. Richening the secondaries helped a little. Also found out my rear end ratio is in fact a......3.25!!! Awesome! Not. Guess that explains why she's kinda doggy eh?
I will adjust the spring tabs in the dizzy to try to get the timing in sooner, but I think she's likely as good as she's gonna get...
I know you are bummed with how sluggish your truck is, but I wanted to compliment you on how great looking it is! It has one of my favorite color combos and looks to be in awesome shape!
I know you are bummed with how sluggish your truck is, but I wanted to compliment you on how great looking it is! It has one of my favorite color combos and looks to be in awesome shape!
David
Thanks, she really is a nice piece when she wants to be! Goal and long term plan for her is maintain and upgrade what's there IE: leveling out the front and rear end, redoing the brakes to larger F250/350 specs, etc.
Got her running about as good as I think she's gonna get. To everyone following, here's the setup, the low down, and the end result. Starting from the top to bottom...
-Edelbrock 1406 carb jetted and rodded to 1405 specs with .101 secondaries. Fuel pressure @ 5.5psi running.
-Stock intake
-Stock dizzy, both yellow springs installed from my Crane kit, Crane vac. Advance turned all in. 15L slot.
-8* initial timing
-38* total timing
-Timing chain in straight up
-Stock everything else
-3.25 limited slip 9" rear end
-235/75r15 tires
-Holds 18" vacuum idling
-Vac. Advance on manifold vacuum.
Advance now appears to come in around 1000 after benning my spring tabs IN. PO bent them out and I left them that way until now. Springs are fully relaxed and everything is returning back to where it should be.
Won't chirp the tires. Won't light em off a red light either. However, mash the gas and the engine takes off and now pulls the truck with it. May tune secondaries a tiny bit, but for now, gonna drive as is and watch mileage unless anyone here sees something else I should look at.
May or may not look into 4.10s for the back end...would love to feel the torque and burn rubber but don't wanna murder my mileage any more than I already am haha. On her test drive tonight on the highway she burned about an 1/8 tank doing 70 for about 30ish miles. Not too bad. I know my 1411 returned excellent mileage on the highway compared to the 1406 the last time I made a long highway excursion, so we shall see.
Compression test will be soon. Also hope to take a dye grider to the heads this summer to remove the exhaust bump. Still has a slight shimmy at idle sometimes, but not too worried about it....right now.
Well there ya go everyone. First off thanks for the help. This has been hell. Second off, anybody see anything else I should change? Tweak? Tune? I'm interested to hear everyone's thoughts.
When you get the ignition sorted out, then dial in the carburetor. As suggested above...The widebands are pretty slick... should be able to pick up a few mpgs by careful tuning. It will still run just as good, if not better, it just won't waste fuel. With 3.25 gears it should be a good highway cruiser.
When you get the ignition sorted out, then dial in the carburetor. As suggested above...The widebands are pretty slick... should be able to pick up a few mpgs by careful tuning. It will still run just as good, if not better, it just won't waste fuel. With 3.25 gears it should be a good highway cruiser.
Wouldn't mind getting one of those wide bands for tuning purposes, just gotta let my wallet rest a bit after the money poured into this thing so far. Seems as if the ignition and the timing curve are dead on for max power without ping. The 3.25 rear end does make her pretty amiable out on the highway I will admit that. I have recorded mid double digits with her more than once and I can't complain about that haha.
I second the wideband tuning. I bought a summit gauge kit and wired 12 volt plug for power to it from cig lighter. I just run the wires to the 02 sensor out the window and hang on the mirror and go for a drive with a note book and guage on the dash pad. I take notes rpms and readings. I was able to get a much finer fuel tune including accelerator pump settings and volume. You just need to understand what your carb is doing and when, such as accelerator circuit, primaries secondaries etc and observe fuel ratio and you will know what to change if needed.
When i am not using it, it goes back in the box and a plug goes in the exhaust with antisiezed threads.
Another vote for Wideband. I have run an 'Innovate' gauge and digital controller in my Valiant after doing a lot of research and finding that many independent tests found the Innovate was a bargain for the price - very accurate, very low response time/latency, and at the time of the article it was about US$150 for the kit.
I have had mine for 3 years and it always works a charm. If anything it let me understand a lot more about carburettors by simply being able to see what was happening as it happened.
Plug reading works but it takes some experience, especially with modern fuels. The widebands cut through that.
Someday I will purchase a wideband to fine tune the cars in my fleet. And by someday I mean when I am not puking money into this truck haha.
Finally got her out for a decent highway drive. It was lackluster to say the least. Going up hills was just plain bad. It felt like she was breathing through a coffee straw. Flat highway was fine, but my foot was way into the accelerator to keep her at 65mph. This has always been an issue whenever I've run a 600cfm carb on this truck. Didn't ping though! In town driving is okay for what it's worth.
My 750cfm 1411 is waiting to be tossed back on as soon as the weather warms up again this weekend. I will leave it in stock calibration and take her for the same drive again. I'll report back with info after!
Have you done the compression tests yet ? (Costs nothing !)
Is your PCV system in order ? (Costs only a few $$$$$ if not. )
I have not yet done the compression test. It's on my list of things to do but work has been hell the last few days since I got the truck running.
PCV system would appear to be in working order as well. I have the PCV valve hooked into the the rear port on the carb, and the vent from the valve cover hooked up to my air cleaner. If I pull the PCV valve out of the valve cover while the engone is running, I immediately get a very large vacuum leak till I plug it back in or cover the valve with my finger.
Ummm, no !
Your work should have been heaven since you got the truck running. LOL
Just check that the pcv valve actually works, and if there's a filter (inside the oil filler ?) on the air filter side, that it's clean.
At least you can tick the ignition off your check list coz it's ''good enough'' and unlikely to be causing the major power loss.
I hope the lack of pinging made you a tiny bit happy.
Are the carb butterflies opening fully, and is there nice big squirts of gas from the pump ?
I'm not familiar with the 'ohm' ratings on your coil etc, but I'd still get a second (or more) opinion. (Too much resistance in that circuit kills power.)
Ummm, no !
Your work should have been heaven since you got the truck running. LOL
Just check that the pcv valve actually works, and if there's a filter (inside the oil filler ?) on the air filter side, that it's clean.
At least you can tick the ignition off your check list coz it's ''good enough'' and unlikely to be causing the major power loss.
I hope the lack of pinging made you a tiny bit happy.
Are the carb butterflies opening fully, and is there nice big squirts of gas from the pump ?
I'm not familiar with the 'ohm' ratings on your coil etc, but I'd still get a second (or more) opinion. (Too much resistance in that circuit kills power.)
By the way, very nice truck.
Haha thanks. Yes the no pinging has made me quite happy! In town she's got plenty of power. It's just on the highway that she really seems to be unable to breathe.
I need to get one of those little filters for inside the air cleaner for the PCV. Currently there isn't even one in there. Removed the old one a lob while bck because it looked like charcoal.
Yes the butterflies are coming open fully. We verified this as we installed the carb. The pump shots are nice and even and strong too.
I don't know why, but this motor has never really liked the 1406. Feels happier in town but I've always had issues with it out on the highway. Going off plug readings, it was lean on the 1406 calibration, so I changed it to the 1405 calibration to compensate. This made highway driving a tad better, but I still find my foot in it a lot just to keep up with traffic. The 1411 has never had this issue. I figure that since it's free, may as well drop it on and see how she does!
