What Next? 1973 Ford Contry Sedan

Saw a t-shirt I wanna get: "Engineers design things, and technicians fix the problems they create."

 

So today I received the vacuum modulator & installed it on the C6. The return goes to EGR port on the carb. Of course,new rubber parts,etc. Surprisingly,the engine can still spit back,shudder,and even one backfire (hopefully,no exploded muffler) after running JUST FINE for awhile. (Passenger was ,like,"OMG! A bomb!") then I realized they had been in a combat zone...I removed the vacuum from the advance and plugged it,and no more backfires/spitbacks/shudders. WTF? Am I doing...Anyway,it seems to want more advance than the centrifugal can give it,but the diaphragm is what? needs more adjusting? Defective? When I last tested it with strobe,advance looked normal on the vibration damper.
So,w/o the vac adv.,it runs almost OK,but not at WOT. Do I need to go richer on the idle? Or what...I am bananas going...

 

I worked with an old guy that would get frustrated and say for instance "I'm gonna go down To the Toyota dealership and punch the first person that I see that works there in the mouth " referring to some wack job design that was dang near impossible to work on and requires "special tool #92876" of which he would produce a tool or something he "engineered" himself and 9 times out of 10 did the trick!

 

Yeah, I used to say the same thing, except I would use the line from The Great Santini: "Castro, you sonofab!tch, I'm gonna chase you down the streets of Havana in my F-4!"

 

I'd prefer an F-105D,but my eyesight kept me out of the Air Force! The '73 drinks fuel like an F-105,so I'm partway there. Anyway,today I ripped out the air conditioner,finally frustrated with too-tight access to the distributor. As a result,I had to fabricate a support for the power steering cooler,which sits atop the compressor,so once the compressor was gone,just a big space.
The engine runs great for awhile and starts sputtering and spitting back. A light foot gets you down the road,but tip into it,and chugga plotz! So: Timing @ 12B,dwell @ 30,points @ 17,vacuum advance at zero and then disconnected and plugged (I've tried several settings),it does advance the timing,but doesn't help the chugga problem.
I even tried 6B timing,but that wasn't any help. As I crawled under the car and inspected the damper,wanting to make 2 marks,6 & 12,with Wite-Out,I saw that the people who timed it after the timing chain job marked two marks over,evidently thinking that it was 12,but as we know,that is 14 (each mark being 2 degrees). I made my marks at 6 and 12,6 being what it was before the midyear change in 1973.
Again I am mystified as to what could be going on.
Tomorrow,I'll look at each spark plug. I'll check again for vacuum leaks.

 

At least your's is running, kinda, my barge's engine is completely disassembled and waiting for a total rebuild.
I'd count yourself lucky it's running at all, but I have faith in you, you'll chase that rabbit down and get it going 100% again.

 

Well, I couldn't get in Naval Aviation for the same reason, along with my excessive height (you'd think, that as big as an F-14 Tomcat was, that the max height would've been taller than 6'4". But, if you're such a fan of the Thunderchief, I now know what to call your CS--"Thud."

 

Not so bad if it goes "Thud",as long as it doesn't go "Bang!" So,I was 90 miles away for the Easter weekend and I stopped in at a garage I'd seen before. He has,among other cars,a red '66 Ford Galaxie 500 Convertible. We discussed my problem,and he said he could fix it,and that it was probably the power brake booster. When I road tested the car last week,I had everything vacuum disconnected,except the booster and the vacuum modulator. Since I just replaced the modulator and its tubing,I wouldn't suspect it. Now I could go out w/o booster & see what happens...That is to say,drive for a dozen or so miles and see if the engine acts up.

 

That was one of the things someone mentioned at the beginning of this thread. But with the other problems, it was difficult to separate everything.

 

Power Brakes OK,must not be a vacuum issue. The engine backfires through the exhaust,another muffler destroyed. Not so much buggity buggity today,but sometimes backfires when you go from WOT to closed. The engine develops good power at WOT getting on the freeway,and no hiccups. What IS the problem with this engine? I'm still dreaming of dropping in a 428...

 

What next indeed? I think you should change the name of the thread to "one last thing" . Maybe the "what's next "is bad juju. didn't you have it at the shop for timing chain? Did they offer any advice on what the heck is going on here? I feel for you brother. You have more patience than I! Hang in there!

 

Backfires through the exhaust...three things can cause that. Retarded timing (not likely but should be checked), a rich-run condition, which can be checked by pulling and reading the plugs, or a misfiring cylinder (sticky valve, grounded spark energy, low compression). Is it like a "POW POW POW," or is it like "pop pop pop BANG?"

 

It is just a "Bang" after WOT,and lifting my foot quickly. And the muffler bellows out. And not a backfire every time (it happened three times exactly this go round. The plugs are perfect,except for #2 & #5,which are a little dark and have oily threads. I don't know what the heck is up with that! I checked compression a while back,was OK. There is something unusual going on here. If compression was OK,how could valves be bad?

 

I don't necessarily think the valves are bad; the blackening could be from bad valve stem umbrella seals.

 

Then when I pulled #2 spark plug again,it was light tan in color,so I don't know what. (I was checking that #1 was on comp. stroke,why not look at #2). And as I rechecked the gap without changing it,the dwell went to 24. (Was 30). Reset the timing at 12B,the engine ran flawlessly,made good power for quite some mostly freeway miles,then as soon as I was happy in traffic,it did the light throttle shudder & jerk routine,which calms down once you add in more accelerator,but you can't keep that up,there are other road users. I cranked in more base idle speed,didn't help.
Then I Googled "Worst Ford V-8 Ever?" And on one of the resulting sites,a poster asserted that the 351M/400 engines required a special thermostat,which if not utilized,would result in cyls. 4 & 8 getting too hot. New one on me! The engine hasn't backfired again,and the muffler is not leaking,it is only slightly bulged,but obviously not a good thing.