'47 Woody engine trouble

[digbar]

I've been working on my neighbor's '47 Woody's engine. It was mising real bad and backfiring when I drove it to OSU airport for the visit by the EAA Trimotor.

We replaced the wires, plugs, caps (it takes a pair - the one with the wires plugged into it, and the one that KEEPS the wires plugged in), and rotor. We also checked the coil - nice, hot spark. Getting 14Kv at each plug, per Fomoco spec. I rebuilt his spare carb, but we haven't installed it yet.

Naturally, the engine idles OK, but give it some gas and the racket starts - missing, backfiring, etc. The next thing I'm gonna do is check compression.

We tried adding some choke to see if the mixture was lean and causing the trouble, to no avail.

One clue - the worse it ran as I drove to the airport, the cooler the temp gauge read!? Go figure.

Any clues or advice? I'd sure like to drive this old girl in the 4th of July parade on Wednesday: gets lots of looks from "mature", interesting-looking ladies!

digbar, security officer, gyro pilot wannabe and certified windmill mechanic

 

[scottessex]

Have you checked the timing? does that use a manual advance?

 

[dragonflyerthom]

Cooler Temps could be too much gas and the extra is cooling the engine. The backfires can be attributed to that also. I think you are on the right track with the carb. Hey I'm an accountant not a mechanic for what it's worth.

 

[jcarleto]

That sounds like a timing problem, but it could also be a vacuum leak. If it has a timing chain, check it hasn't hopped a notch. I think those had gears, though. If it even has a vacuum advance, that's the first place to start. Either a timing issue or vacuum leak tend to make those old Fords run rich, which could result in less active combustion.

 

[karlbamforth]

It could be an induction leak or a cracked exhaust manifold, both will give backfiring. Induction more when running at high rpm, exhaust more on the overun.

 

[WHY]

Possible ignition coil (system) break down at faster speeds ?

Tony

 

[Cobra Doc]

Timing advance or valve timing. I'd start with the ignition system. Could be carb but it's not likely unless ignition and valves check out.

 

[dabkb2]

sounds like cam timeing to me, but from here it is hard to tell, good luck

 

[GyroRon]

Maybe it is time for a new car? Kia makes some good cars these days that even come with a 10 year, 100 thousand mile warranty! just kidding ya, I am clueless as to what the problem is

 

[digbar]

47Woody

47Woody

I checked the compression this afternoon. Cylinders averaged 6:1 compression, with 1 at 7:1, 1 at 3:1 (!), 1 at 4.5:1 (?), with the rest a 6:1.

I suspect the distributor - vacuum not working right, or bad points. We got 2 distributors coming - 1 with electronic ignition that we installed about 4 years ago (gogadget please note). I bet one of them will fix it.

I checked the vacuum at the manifold yesterday: 23 inches! and steady, so I suspect the intake valves are OK. This old girl does have a shot manifold gasket, where the cross pipe connects on the passenger side. We'll fix that soon, and we'll also get the rebuilt carb on soon. Gee, I hope we can make the parade with her. If not, Larry can drive his Model T pickup and I'll drive the Model A.

Thanks for all the comments: I made a list and will run it down tomorrow. Thanks again.

digbar
Old age and treachery will overcome youth and vigor every time!:hail:

 

[M. Pearce]

digbar,

Put some marvel mystery oil in it.

Sounds to me like sticking valves.

 

[giro5]

I would replace the distributor cap and check the points and point backing plate for tightness. I once went through everything on an engine for misfiring starting with the points, dist. cap and rotor, new plugs, plug wires, new timing chain, new lifters new gaskets vaccum tests etc and after everything and I mean everything was replaced it still misfired. I started over with the points. It turned out to be the backing plate was loose and so the point ground was intermittent. Sure ran smooth after all that though.

 

[Cobra Doc]

digbar,

Put some marvel mystery oil in it.

Sounds to me like sticking valves.

and rings!! I've never seen that much variance in a running engine. Sounds like pretty much everything is sticking or worn out. MMO in the gas and oil (instructions on the bottle) should start smoothing things aout to give you an idea where to start. I don't think it will make the 4th of July parade this year.

 

[M. Pearce]

Cobra Doc,

My Dad passed away this past November, 2006.

Dad had this 2000 model Dodge Caravan that he figured was on it's last leg so he bought a second hand truck to take it's place.

My brother started the van one day and it was knocking so bad he shut it off right away.

Well long story short, I ended up with the thing because no one else wanted it after eight months a setting up and knocking.

I figured what the heck, change the oil to see if metal shavings come out.

No shavings were anywhere.

I put one quart MMO in it in place of a quart of the usual 10w30 during the oil change.

Within fifteen to thirty minutes the engine was running knock free and purring like a kitten.

My Grandpaw always told us Marvel Mystery Oil was some good stuff but until last couple weeks I have only used the stuff for some squeeky hinges round the house.

That 47 Woody would sure be high on my list for some.

The van didn't have sticking valves but when I used to work as a mechanic I'd occasionally find an old dog that did.

A case of sticking valves can make the best of machanics go nutz.

So yep, sounds like Woody is all crusted up inside.

I just wonder how long it has been setting up????

 

[digbar]

We'll get a quart of Marvel in her quick! We used some in a Cessna 150 over at Port Columbus about 20 years ago, and it did the trick. It couldn't be that my memory is failing after all these years, could it?

Thanks again
Digbar

 

[Rick Whittridge]

You never know what will POP out of Mr. Gadgets hat (A CDI ?) but MMO is GOOD stuff for all 4 Stroke engines.I put some in the Twinstarr tonight!
All it Takes is Comp,Fuel,& a good spark & Magic happens!
Good luck with the parade:yo:

 

[Cobra Doc]

I use Marvel in the gas when valves are getting stick or I do an engine rebuild. I love the stuff. When using it in two-stroke gas, use half what it says to use. It frees up the rings pretty quick but if you use the full amount per gallon it will look like you are fogging for skeeters!
It also works great freeing up old model airplane and car engines.