66 Mustang Reset

Harlon

Well-known member
Son bought a 66 Mustang Coupe with a 79 Fairmont L6 200 last summer.

Budgetary issues stifled any potential work until now.

Decided to invest $1000 into the project while his funds are dedicated elsewhere.

Long term plans likely to include rebuilding the engine to improve CR and machine the head to accept a direct mount 32/26 carb. All the head and block machining and upgrades detailed in the FalconSix book. Long term will wait til he has funds to contribute.

Short-term - tune it up and improve operations so that it consistently starts, stays running and responsive throughout the “power curve.”

On the tentative list:
1. Upgrade Ignition System: HEI or tweaked DS11 from BIll, or a DUI.
2. Carberator Upgrade: 32/36 carb with adaptor.
3. Exhaust: VI or Clifford Header and appropriate exhaust.

I’m fairly certain we can do at least two of these for our $1k budget but likely not all three.

Now to the question - engine viability?

Little more background detail. We started the tune up process.

Changed the battery, old one flagged bad on the charger and wouldn’t hold a charge for more than a day or so of sitting cold.

Moved on to checking the plugs. Pulled the spark plugs to see how they looked.
1 - looked decent light tan, no build up
2 through 5. Various levels from all black to black with carbon build up. At least 2 were wet with oil.
6 - similar to 1 but a little darker tan.

From what I can gather 1 may be running a little lean, 2 through 5 are likely running rich, and 6 is running pretty good.

My thoughts are that it’s running lean on the ends, 1 and 6, and rich in the middle 2 through 5. Isn't this indicative of the poor flow from the log manifold?

Question #1. Will a better tuned carb and more consistent ignition help these issues? Is this a correct assumption?

Question #2. How big an issue is the oil on the 2 plugs, don’t remember which cylinders? Is there a way to establish if it’s rings, valve guides or something else?

Thanks for the help.
 
Hi, do a compression test and a vacuum test to learn more about the condition of your engine. Good luck
 
Howdy Harlon and All:

I sure like your plan and your budget realities. First to your questions.
Question #1. Will a better tuned carb and more consistent ignition help these issues? Is this a correct assumption?
Answer #1. Yes. But first, which carb are you currently using? The '66 carb would be an Autolite 1100. That would mate with the '66 throttle linkage. If that's what you are currently using then YES! And, the '66 1100 is designed to work with a '66 Load-o-Matic advance system in the '66 distributor. So, which carb are you using now?
IF it is the '79 Holley #1946 then possibly less likely.

Question #2. How big an issue is the oil on the 2 plugs, don’t remember which cylinders? Is there a way to establish if it’s rings, valve guides or something else?
Answer #2. Yes. As Ron suggested a compression test and a vacuum test will tell you alot more about the inner condition of the '69 engine. But, do you have any idea of it's condition before it was swapped in to the '66?
Another possibility is that the valve stem seal are shot an allowing oil to leak down into the engine through the valves. Typically, the #1 cylinder shows oil leakage first, then #2 and on back. Wasted valve seats are pretty typical on these old engine. FYI oil is pumped up into the head through the last head bolt on the Driver's side rear head bolt and transferred to the rear
rocker arm stand and down the long rocker shaft to each rocker arm. The front rocker arms are the last to get oil and remain without oil for several seconds, even minutes, on start up.
The compression and vacuum tests will help point you in the right direction, and possibly removing the valve cover for a visual inspection.

So, IIWIYS, and I had $1,000 to invest in making this engine reliable, I'd start with the DuraSpark ignition that is on a '79 200. Refresh, clean and/or replace pieces as needed, but make sure that the advance mechanism is working properly. Fresh plugs and plug wires are a good place to start. Now assuming that all is working as designed, set the initial advance at 5 degrees more than the stock specs.

On the carb, why are you choosing the Holley/Weber to upgrade?

On the exhaust, I'd save that til last. It will be the most expensive and without an upgrade in the head work and a performance cam will gain the least. Again, IIWIYS, I'd settle for replacing the exhaust system with a 2" head pipe with a 2" turbo type muffler and a 2" tail pipe. That will give you a pleasant sounding exhaust and a foundation for when you are ready for the header upgrade.

Well Harlon, how about some more info from you. Oh, and good luck.

Adios, David
 
Let see here,

1.) The Carb is the #1946 from the 79 Fairmont donor.

With that, the tentative choice to swap for the 32/36 is basically arbitrary. Long term we do want to improve performance with a head rebuild to include the direct carb mount. The 32/36 seems to be a common two barrel upgrade and relatively available. I can also say that I do like the idea of the progressive linkage for combined economy and performance. Also, note that it is a “tentative” selection. In the end I want to choose something that will improve performance while also improving reliability and ease of maintenance.

2.) I don’t know much regarding the health of the engine. It has been relatively maintained by someone with enough knowledge to rig things. For example the horn and reverse lights were rerouted to switchs fixed on a makeshift panel below the dash. Someone knew enough to be able to bypass the neutral safety switch and turn signal switch to keep it operational, but not necessarily well maintained. Wiring issues have been a real headache. If the general running reliability hadn’t become issue I think we’d be planning a total rewire.


All this said, right now we’ve kind of stalled out. The new battery I mentioned earlier. Well, we didn’t work on it for 3 days after install, and now the battery is dead. Parasitic voltage drain? Unfortunately, I didn’t anticipate that one. So, we roled the car out of the garage before trying to start it. Now it’s parked on the street at the end of our steep driveway surrounded by snow. Smart.

Got the battery out of the car and recharged. Tomorrow we’re going get it running(hopefully) and back in the garage so we can start hunting the voltage drain(maybe we’ll be starting with a total rewire after all) and do the compression test.

Thanks,

To be continued,
 
That carb could work for your starting budget if it's in good shape. Which Distribitor do you have now, or if you don't know take a picture of it? If they happen to have used the 1979 DSII than you would be matched up great and your budget could go to other needs.

Yes it sounds as though you will need to do some work on that wiring first, to correct what's been butchered. First steep check condistion of wiring, all conections and the grounds. For safety you should disconnect the battery when your not working on the car until you find out your load that's causing the dead battery in case its from a short I have seen more than a few cars bunt to ground from these hacked up wiring jobs. One normal example though is a bad dome light switch or worn out ignistion switch that's sticking, an aftermarket stereo radio or some other accessory items that someone wired direct instead of through the ignistion switch or a relay. Good luck (y) :nod:
 
I’ll throw some pics up eventually, but I’m fairly certain I’ve got the DS11.

I’ll know more later, but the battery issue may not end up being the car’s fault.

I haven’t been able to get the new battery to take more than 12.08 volts with the charger. So assuming the charger isn’t faulty we might have gotten a bad battery from autozone. Unfortunately the charger is new as well so I can’t rule that out either.

Thanks,
Harlon
 
Howdy Harlon:

Sorry for your misery. The good news is that the #1946 carb from '79 is compatible with the DS II so far as vacuum advance goes. While the #1946 is not very user friendly the '79 version is only slightly better than later versions.
FYI- the two stage two barrels are finicky to get tuned. IIWIYS I'd probably stay with the 1946 until you can do the head with direct mount. I'm partial to early Autolite 2100. easy to tune and easy to maintain.
How did the PO rig the throttle linkage? Are you using the auto choke on the 1946? What trans? I'll be anxiously waiting on the results of the compression and vacuum tests.

Keep it coming.
Adios, David
 
Got a little closer on the battery issue.

Got a minimal charge on the battery. 12.21 volts. Not 12.6, but enough to get it back in the garage.

Did a parasitic draw test with my multimeter. Something is pulling 1.39 amps when the key is out and door is closed. My understanding is that it should pull less than 50 milliamps. Guess tomorrow we’ve got to pull the seat back out and get under the dash at the fuse panel and start checking fuses.
 
A full battery charge is in the range of 13.4 to 13.8 volts. Yep 1.39 amps is quite a draw. Good luck in the hunt (y) :nod:
 
Question:

For the compression test, my old automotive textbook says to disconnect the primary wire from the coil. On my coil I have one of the “c” shaped connectors/harnesses that slides over the top of the coil to connect both wires. One goes to the key and one to the module. Do I just pull this off or do I need to pull it off and also unplug the other end from the module?

Thanks
 
Harlon":v1lvxt9e said:
Question:

For the compression test, my old automotive textbook says to disconnect the primary wire from the coil. On my coil I have one of the “c” shaped connectors/harnesses that slides over the top of the coil to connect both wires. One goes to the key and one to the module. Do I just pull this off or do I need to pull it off and also unplug the other end from the module?

Thanks

When I do a compression test I remove the coil wire AT the distributor, rather than AT the coil. Not sure if that's correct, but it's always worked fine for me.

Cheers,
M
 
Just pulling off the "C" connector at the coil is fine.
The object is to prevent the ignition system from making high voltage.
 
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