What Next? 1973 Ford Contry Sedan

Well,the car was driveable for much of the two years,but now it's not. Especially since it is back to Exploding Muffler Syndrome. My point is that how could it be any of the things I've replaced,because the problem keeps coming back in spite of externals. So,I have recurrent theories:
What if the exhaust were intermittently blocked on the short side of the "Y" pipe? I have only the paperwork from the first guy to work on it when it arrived from Wisconsin,and he wrote "Replaced short section of Y Pipe",which is weird,because the Y-pipe is one piece. His idea was that there was an inner pipe inside the Y-Pipe which self destructed. He is out of business now. And all the exhaust system parts except the muffler are made of Unobtainium.
And the car has been in shops, and left them running OK,so WTF?
I just wonder if the supposed blockage could cause the intermittent rough running/not staying running/muffler exploding problem? And I would say again,I've had more than ten V-8 Fords with points & condenser ignition,and never a problem like this.

 

Well,the EGR was working but the aluminum spacer needed reconditioning. After that,I blocked the whole EGR off. Now I want to cap all the vacuum controls to it and to the spark control,which also is not in use. I'd rule out any vacuum leaks by doing this. And that red box underdash! It is not doing anything useful,but could be sending stray vacuum/electrical signals to other parts of the system. And apparently,this car was built between system modifications,and so has no door pillar thermistor and no air cleaner switch,etc. Maybe I should have made it like a '56 Ford from the beginning. Weather too nasty here to work on it today,and paid work interferes with my fun time anyway.

 

Today I verified the basic timing,struggled with points gap and dwell,and worked on idle mixture. Book says 1 1/2 turns out,that was waaaay too rich.Those little screws are hard to reach! But I got it a good deal leaner,and it drove out better. The two screws should be in balance,seems to me. Maybe I can find an expert locally to find the sweet spot of idle mixture.
Also today,I ripped out and plugged a lot of vacuum hoses--no EGR and spark control anyway. Mainly want vacuum for power brakes,HVAC,vacuum advance & the thing inside the air cleaner which controls the flapper in the snorkel.
There'll be a package in the mail soon with the only plastic choke linkage part--then I can put the choke assembly together and back on the carb.

 

Hook up your vacuum gauge adjust to highest possible vacuum with steady needle . 1 1/2 turns is just a starting point .

 

In the book,they want you to do the idle mixture last,but the 1 1/2 turns of each screw first. I'll make sure the vacuum gauge is attached. There is this handy little spout on the manifold. But I can't really have it driveable until I get that crazy little choke linkage part.
The vacuum gauge does not show the restricted exhaust symptom that I feared in my post above.
It just may be that the only problem now is "Too Rich"!
And the book says "Turn each screw an equal amount". Well,if that's all it takes...
I keep visualizing the carb on my '56 Ford (Well,on one of my '56 Fords) a simple small 2V with easy idle screw access.

 

The way I was taught, is that once the engine is idling, set the P-brake and block the wheels; have a helper put the trans in D. You then turn one screw toward lean until the engine begins to shake, then, looking at the vacuum gauge, you turn it rich to gain the highest reading, going in 1/8 turn increments. Rev the engine a couple times, allow it to settle back down to idle, then do the same on the other. The idle spec should be 700-750 RPM in P, and 600-650 in D.

 

So yesterday,two test drives,the second with a leaner setting. I didn't dare put my foot in it for fear of Exploding Muffler Syndrome,but it ran almost normally. Today I verified resistor wire as Good (rather a big job). Then when I started the engine,it was back to extreme rough running (not really an idle!) and spit back once through the carb. Dr. Jekyll & Mr.Hyde?

 

Thank you,Andrew,for the tip on mixture. Along with that,I still need more choke linkage parts,which are being shipped as I write. It is kinda hard to do anything with the engine without any choke. Although it is supposed to be 50 Fahrenheit tomorrow,so maybe I can get something done. The other item on my list is to find someone local who is versed in old iron to get a hands-on look at this engine and find out why it runs OK/doesn't run at all/explodes the muffler.
I'm remembering now my first 1956 Ford Country Squire,Black over woodie with the basic red & white interior,8-pass.,292 T-Bird V-8 w/Fordomatic (which in those days had 3 speeds),4V w/duals. I paid $35.00 and only had to pay another $75.00 to have a new front crossmember welded in (I don't recall how much the part was at the Ford dealer,but it was still a service part in 1970). Not that the car didn't have problems,but they were solvable!

 

It was you I sent the carb parts to, correct? If you take a few clear close-up pics, I can see if there's anything you're missing.

 

And we had a '56 Country Wagon with the 292 V8, which Dad always called the '202 HP' engine. Apparently, it was a hot potato back then. Unfortunately, we were moving across country before Dad went to Viet Nam in '68, so he gave the car to a neighbor high school kid for his agri-mech studies.

 

All the '56 V8 wagons had 4V carb/dual exhausts. "M" cars had the 292 T-Bird engine, and "P" cars had the 312 at 225 hp. I had one of those in 1976,but for some reason swapped in a '55 272. Today, I think of my '73 as a substitute for a '56 wagon,but if it were my mistress,it would be lazing on the couch eating bon bons and watching soaps. "Get up!" "Aah,no."
Yes,you did send the choke housing and thanks,but that was on the original carb. All I need now are the little plastic lever and the ring that secures the thermostatic housing,and those have already been shipped to me.
I may just give a call to the local differential expert to see if he does engine work too. He's seen the car,driven it,evaluated it.

 

No, you haven't. You've only verified that your timing light flashes when your #1 plug fires at the correct degrees on your harmonic balancer. That doesn't mean it's correct. That checks spark timing, but not valve timing.

Exploding mufflers are caused by raw fuel being ignited in your exhaust system. This can be recreated by accelerating to 50 mph, turning your key off for a couple of seconds, and then turning it back on (don't do this if you have a locking steering wheel). The raw fuel that went into the exhaust will ignite and it will backfire.

How can this happen on your car? Have you ever noticed a fuel dragster with zoomies when they stage? They are puking raw fuel from the exhaust. Because of the wide overlap on their cams, the engine is firing when the exhaust valves are partially open. You don't have a radical cam, but your engine is firing with the exhaust valves open. You're timing is way off and has nothing to do with your timing light settings or your carburetor.

Either your harmonic balancer ring has slipped or you have a huge amount of stretch in your timing chain. I suspect both. You are chasing unicorns farting around with all that other stuff. Until you fix them, nothing else you are doing will make any difference.

 

Well,Old Fox,that certainly makes sense,because everything else has been covered. Saturday I replaced the points they gave me with the reman distributor with a vintage "Blue Streak" set & got gap & dwell & idle mixture etc. within spec and drove the car,even doing WOT acceleration & 70 mph cruise,so there's that.
The vacuum gauge needle is jittery at idle,and so is the 12B mark on the damper. The car still idles rough. I didn't find any vacuum leaks. I still have to put the choke parts together and attach all that to the carb.
As for the timing chain/gears/harmonic balancer, all I can do now is tear it down in the yard or ask the shop to do it. I have the shop manual right here,and step by step,it looks to be a daunting task. They want a white lead and oil mixture to mate the damper to the crankshaft. What the heck is white lead and is it not used anymore? And why do they want you to drop the oil pan at the end and reseal it?

 

The timing cover fits to the pan lip in such a way that it comes off with some force, but it's damned near impossible to get it back on. On my '74 Ranchero I used to have, in order to install the timing cover without undoing the oil pan, I took a pair of tin snips and trimmed the inside corners of the pan seal channel, allowing them to slide over the pan rail at the corners. I just made sure to put extra dollops of black RTV silicone on each corner of the pan before installing the cover.

There is one last thing you can do before tearing into that timing set: turn the crank until the 0* mark is at the pointer. Then, watching the dizzy rotor, slowly begin turning the crank, and stop when the rotor begins to move. Then look at the timing scale. if the crank can turn into the chain stretch and move the rotor no more than 7*, the timing set is more or less within spec. But if it exceeds that 7*, then you should do it. Once the cover's off, you'll be able to see just how much stretch there is. 1/2" maximum stretch on the non-tensioned side is maximum. And take a close look at the dowel pin on the cam snout and the Woodruff key on the crank snout for damage.

 

There is allot involved if you determine that the timing chain is your problem . Not an easy task doing it in your yard . Not here to ruffle feathers but it might be beyond your mechanical ability . True TDC with valve cover removed to verify and the proper alignment of marks on both cam and crank gears . With all that you have done and as Old Fox said remember valve timing and how it all comes together . If things are correct your vacuum and timing mark should be steady .