Compression Depression

Have you loosened the rockers and pumped air into the cylinders to see where it exits? That would be a fairly quick way of telling if you have a piston/ring/block problem or gasket/head/valve problem. That is what I did to mine, air came out of the cylinder next to the one in question, led me to believe it is a gasket or head problem. I should get the heads back from the machine shop this morning.

Your right, your numbers suuck. Sorry, hope for the best.

Yep, I would like to meet up some day. Maybe before Daytona if I get one of these cars together and running. sheesh

Angelo

Marvel mystery oil squirted on top of the pistons, 1qt with a fresh oil change as long as the oil has not sludged up over years of sitting, is the car running? If so let it run at an idle and warm up and keep an eye on the oil condition as the sludge & gum'd up ring will hopefully loosen up, also use in the gas as directed, If these parts are saveable this is the stuff to make it happen!

Mark

Sooooo.... How goes things? What was the outcome with the compression?

Angelo

Not particularly well. I am concerned that my oil is being diluted by a leaking fuel pump. I am not certain how to check for diluted oil but the oil seems a little thin to me and I may have noticed a slight increase in the oil level.

I am fearful of starting the engine until I am certain that I do not have an internal fuel leak. Any suggestions? I intend to take off the fuel pump this weekend and look for a suspect internal gasket. Have a great Thanksgiving weekend.

If you added Marvel oil to let things soak, esp in the bottom end, you will get a increase in oil and it will be thinner. Did you check the fuel pump?

Or did you skip out and go the the turkey run in Daytona? I missed out this year, will make the spring show I hope.

Angelo

I tested the oil and sure enough it contained gasoline. I changed out the fuel pump, the oil and filter.

The car started easier with the new fuel pump and idled properly until the water temperature reached 160 degrees. At that temperature a persistent misfire occurs that increases in frequency as the water temp goes up; the same problem that I have had for months since purchasing the car.

I believe that I have a problem with either my
vacuum advance or the EGR valve; something for me to trace out this weekend.

Once I get the car running a little better I will try your Marvel Mystery Oil solution and let you know how it works out.

And no, I did not make it to the turkey trod at Daytona but I was there several weeks ago for the Rennsport Reunion which was a great show. Bruce

If this is a 1972 351-C, may I ask why you are still running an EGR valve? Fords are well known for failing the carb-mount source for EGR inclusion as well as most other smog stuff within a few years from new. I would take all that antique stuff and place it in a box somewhere, since as a 35-year old engine, it certainly has done its part for clean air up until now.
'Stuck' rings usually happen because of charred oil built up behind and around the rings. This stuff is hard enough to need a lathe tool to cut free; good luck with any chemical. The rings also age, overheat and lose their tension against the cylinder walls, creating more blow-by. This engine badly needs a real leak-down test by a good shop!

I hate to show my ignorance but I am unsure if I have an EGR valve. I was under the impression that the EGR valve is located in a spacer plate under the carburetor. My carburetor is a Motorcraft 4350 and while there is no spacer under the carburetor there is a metal tube which appears to be an integral part of the carburetor. A rubber hose connects the PCV on the left valve cover to the tube previously described.

My car is serial number 04236 which I believe is a late production run 1972 Pre-L. In this model year does the base of the carburetor contain the EGR or have I mis-identified the carburetor components? If the tube is a part of the EGR do I disconnect the rubber hose, plug the metal tube at the carburetor end and connect the hose to a crankcase vent canister that I could mount in the engine bay?

You advise would be sincerely appreciated. Bruce

No, thank goodness; that is not an EGR which is always an iron casting with a big diaphragm & a vacuum hose to its top. What your rig is, is the stock PCV recovery system, and it does no harm as long as the valve in the left rocker cover is still operational (they plug up over time). Its possible to install a new PCV upside down, and if done, will magically turn your car into a mosquito-abatement machine in right turns! Some '74s and some later gray-market Panteras did get EGR, and its a nightmare to keep running!
Another part of the minimal smog equipment '72s got is an idle-speed-increase solenoid and a charcoal cannister under the rt quarter window. The can is the termination of the gas tank vent line with a 2nd line going from charcoal can to the air cleaner. These things go non-op within 5 years from new and after that, are just along for the ride. They are sometimes the source of a gas smell and are unrepairable but can be replaced new from Ford at some cost. I usually disconnect the line to the can and hook it directly to th base of the air cleaner with a Fram filter made for exactly this use. The can and most of its lines are resting comfortably in a box in the garage. The idle solenoid IMHO is a joke: it had a thermal switch that increased the idle speed from around 650 rpms to around 900 when the engine began to overheat. The theory was, higher rpms speeded up waterpump circulation thru the radiator and cooled things down. In practice, it increased temperatures, caused boil-over and should be disconnected.
On your Motorcraft: you have a genuine antique there for which very few parts or gasket sets are available, no one I know will overhaul one and Ford will be no help at all. Either a Holley 600, a Demon from Barry Grant or one of the Edelbrock carbs in similar size will undoubtably get your car running better, with far better fuel mileage.

Thanks Bosswrench for your reply. My 72 has a Distributor Vacuum Control Valve that screws into the water pump. There is not an electrical connection on top of this device as shown in the manual. I was convinced that the thermostatic portion of the valve was bad so I took it out and installed a brass plug. While unscrewing the valve I broke off the small tube that connects to the distributor advance.


The local Ford dealership no longer handles the valve. The local parts house asked me the color of the control valve as they have various colors that designate the operating temperature. The valve appears to be black but it is so old I can not tell for sure. Do you know the proper color of the valve or better yet what temperature it is to operate at?

After reading your response I wonder if the valve is even necessary. Could I connect the carburetor vacuum to the distributor advance and the manifold vacuum to the distributor retard and eliminate the valve?

Thanks for your assistance. Bruce

snip....After reading your response I wonder if the valve is even necessary. Could I connect the carburetor vacuum to the distributor advance and the manifold vacuum to the distributor retard and eliminate the valve?

Sure can, as long as you're using the stock push-pull points 'n coil distributor. If you change to an electronic distributor, just don't get the hoses mixed up- the later units only use carb vacuum (not manifold vacuum).

Thanks, I will give it a try this weekend and let you know how it turns out.

Being a bit of a purist, I say don't junk the Motorcraft carb! It can be rebuilt, check with Pony Carburetors http://www.ponycarburetors.com/default.asp.
Here's some good reading about your PVS (Ported Vacuum Switch) originally posted by George.
http://pantera.infopop.cc/eve/forums/a/tpc/f/5650045562...480090294#6480090294

Thanks everyone for your responses. The carburetor in #4236 was rebuilt by Carburetor Specialties of Phoenix Arizona (602 278-5140). When I purchased the car in March I found a tag on the carb identifying the re-builder. I call the shop owner and gave him the car model and the previous owner's name. He gave me a complete recap on the condition of the carburetor, the flow rates, jet sizes installed, etc. I was very impressed and this shop appears to perform quality work.

Over the weekend I disconnected the Distributor Vacuum Control Valve and rerouted and reconnected the vacuum lines accordingly. Lo and behold, I had the same backfire when the engine temp reaches about 160 degrees.

Several friends visited and listened to my poorly running engine. Finally, one fellow spoke up and stated matter of factly that the engine timing was retarded. I have timed the engine on numerous occasions and assured him that the timing was right on the mark but to pacify the audience I advanced the timing until the backfire disappeared. I checked the vacuum and it was running 18 to 19 psi.

I have read numerous threads about worn timing chains and improperly aligned timing marks. So, this weekend I hope to locate the exact problem and correct it.

Thanks everyone for your assistance. You are of great assistance to an amateur mechanic. Bruce

So how goes things? Compression? engine backfiring? Inquiring minds.....
BTW, what ignition system you running? stock? MSD?

Angelo

On Saturday, December 14th I decided that I would take Rorncat (my Pantera as named by its previous California Owner) for a short drive. She was still running poorly but what could a short drive hurt. After I had been out for 20 minutes and the water temperature had reached about 210, I made a right turn, drove about 200 yards and she backfired out the exhaust and died.

I called the wrecker and I was not too pleased when they thought that this was a 1972 Pinto and had never heard of a Pantera. The second towing service knew what it was but the owner had never seen one. So, the owner arrived first to take photos and to help his driver load my prized possession on the rollback truck.

As I rode home in deep despair the driver claimed to be a former, long time garage owner and he offered to listen to me try to start the car. I turned the key and Rorncat came to life.

Sunday was a beautiful day and I took her out again. Within a mile of my house, the car backfired out the exhaust and died again.

I called a friend and we messed around with the electrical connections at the ballast resistor and the car immediately started.

Our youngest biological daughter was married on Dec 21st so I did not touch the car until yesterday. I started her up and I let her run for a few minutes to bring everything up to temperature before shutting her off. As the water temperature got to 160 degrees the car stopped. I turned off the ignition and let the car cool off for 90 minutes. Without adjusting anything, I turned the key and the car immediately started.

I have some failing component that is heat sensitive. Could a failing ballast resistor or voltage regulator cause this problem? I just installed a MSD Blaster II Coil. I noted that the Blaster required a resistor rated at a minimum of 0.8 ohms. I assumed that the existing ballast resistor was rated at this value but maybe I was incorrect. Could this coil be incompatible with the Pertronix ignition module I installed several months ago?

Any advice from the experienced among you would be appreciated. A good friend has renamed my car "Snorncat" and this has got to end.

Thanks Bruce 4236

My 2 cents here,
Since you say it starts right up and runs fine until you reach temp. I would say that the timing gear is ok. I don't know what emissions equip you have that would affect timing but non of that would affect your timing to the point you are describing.
I have consern with the resister. I have a MSD system and the previous owner wired the voltage to the control box thru the resister. I was running fine at lower rpms but as soon as I ran to 3000 rpm I had severe ign breakdown due to the controller not getting enough voltage for a decent spark, could be coincidense but my temp was also at that range. Once I gave it the 12v it wanted.....happy days. See if your ign requires 12v or the reduced voltage thru a resister. And actually measure it, I thought I was getting 12v but was only getting 4v. The Coil can also breakdown sometimes when they overheat. Ign switch can also be overheating to the point of failure.

When you backfire....is the engine running smooth or is it breaking up....electrically speaking.

Angelo

Just to make sure we are on the same page:

(1) The ported vacuum (port on side of carburetor) is connected directly to the outer cannister of the vacuum advance mechanism with one short piece of vacuum hose.

(2) All other vacuum hoses are removed. All other vacuum connections on the manifold or carburetor are plugged.

(3) The idle is set with the idle stop screw, and not with the idle solenoid. The idle solenoid should be removed and placed into long term storage in the nearest trash recepticle.

If the engine still dies when the engine is set up this way then we shall consider 4 possible reasons:

(a) If the distributor is the oem distributor, the advance mechanism is beyond a doubt worn and gummed up. The advance mechanism may be sticking in the advance position while driving, then when you slow for a stop, there is too much advance at idle and the engine dies. Once the engine dies the advance resets, allowing the motor to restart. A spritz of WD40 may resolve this problem temporarily.

(b) Ignition switch contacts are burned & dirty, creating a point of high resistance & a resultng voltage drop. This voltage drop will get worse with heat (as the motor is operated) until there is insufficient voltage supplied to the Petronix module for it to operate. The engine stops, the switch cools allowing the motor to then be restarted. I highly recommend that all Panteras have current to the ignition controlled via a relay and bypassed around the ignition switch.

(c) Bad Petronix module, gets hot & fails.

(d) Bad coil, gets hot & opens up.

cowboy from hell