The Stovebolt Site Forums The Shop Area The HiPo Shop Miss @ 30+mph, non-typical engine

I need to stray off the usual path a bit as I'm unsure where I can get such a wealth of knowledge as here.
Motor is a V-12 in an orginial 1938 Lincoln Zephyr coupe. Above 30 mph the motor developes a miss. Engine has just been rebuilt with very few miles. Where would be a good place to start looking. Thanks in advance for any and all suggestions.

All engines, no matter what brand, need fuel, spark, and air to run. So a V-12 is no different from my inline. You need to be sure what type of miss it is. Is the engine under a load at this speed? Does it continue to miss going faster or stepping down harder? At what point does it quit and why? How old is the fuel?

A distributor with a loose shaft could cause a rpm related miss, but so could a weak fuel pump or faulty fuel line. Will it miss setting still at the same rpm it does at 30 mph? if not, then I would suspect a load related problem (fuel mixture). Running lean can cause all sorts of problems. Coils can get hot, plug wires can go bad, there are just to many places that can cause your problem.

Try to narrow down just what is happening and how you overcome it.

Joe

Look at the vacuum brake system in the distributor. It's supposed to retract at light throttle, and allow the centrifugal spark advance to operate. The flathead distributors don't have a vacuum advance- - -the brake retards the timing during acceleration, then the centrifugal advance is supposed to come back in at light-throttle cruise. They're notorious for getting sticky and not allowing the advance to work. There's a leather disc in the end of the brake plunger that wears out or falls out and jams up the advance sometimes. Grinding a little off the length of the spring behind the plunger also helps it to have enough room to move. Even with the adjustment backed all the way out, the spring can be too long by about 1/8" or so.

Also, check the distributor housing for worn bushings that allow the shaft to wobble and change the point dwell and timing. That's another chronic problem.
Jerry

This discussion brought back a funny memory. Back in 1965 I had just bought a new 65 Mustang 289 with 4 barrel carb and 3 speed tranny. It seemed to have a miss between 95 and 100 mph. I took it back to McClarty Ford's service department and explained the miss at that speed. The service manager was an older fellow who when heard my complaint told me (21 yrs old) that I shouldn't be driving that fast and not to worry about the miss. I was so shocked and lost for words that I left and took it to the Mercury dealer who was happy to work on it ( faulty plug wires) and to also replace some shocks and a muffler. I only had 250 miles on it but I guess the Merc dealer needed the work. lol
Sorry for the highjacking but I couldn't resist.

I was thinking you might have a problem in your ignition system. If you're running points, I'd look there. Otherwise if you can convert to Pertronix electronic ignition, that might be better. You'd have to call them though to find out if there is a 12 cylinder application.

I sure would love to see a pic of that installation!

Interesting

A distributer has been sourced and will be installed when it arrives. Parts are hard to find and scary expensive. If the moderators allow, I will share my travels with this rare piece of American automotive history.

You have my vote.

Whatever you do, don't discard the old distributor. There are still some of us around who can repair them. A huge number of 12 cylinder Lincoln distributors were converted to 8-cylinder units to run on the dirt track race cars of the 1950's. They had a much bigger coil than the Fords and they gave a very hot spark when set up properly.
Jerry

Do you have hydraulic lifters in that motor? Just curious because I had a 235 out of a car in my 49PU and it had hyd lifters. At speed one of the lifters would sometimes go dead causing a miss. I might be totally out in left field but thought I would mention it.

I believe all the smaller-displacement Zephyr V-12's had hydraulic lifters, and they gave a lot of trouble, mostly losing prime and rattling. I don't recall hearing about a miss caused by lifters. Those engines were chronic oil-burners, and terribly underpowered. A lot of Lincolns got retro-fitted with flathead Ford or Mercury V-8's, which is why the 12's are so scarce and expensive now.
Jerry

I remember back in the 50's all the guys driving old flathead Fords wanted those Zephyr
gears. I believe it may be because of how they were slanted and made a cleaner shift.

Transmission gears fron the Zephyr, and also the Cadillac/LaSalle cars would fit the Ford transmission case, IIRC. Lots of parts like that would actually swap between manufacturers' lines back then. Some of the Lincolns actually ran GM Hydramatic transmissions!
Jerry

They didn't know what a hyd.liftr was in 1938

I beg to differ sir, Check out Cadillac flathead 36 to 48 and Lincoln Zephyr 38 to 42,Packard v-12 after 1935. The technology was out there but seems only applied to the big cars.

The 39 Zephyr engine that my students sleeved in 2007 definitely had hydraulic lifters, just an oddball design. Until the mid-1950's, hydraulic lifters didn't look like the ones we're used to working with, but they did the dame job- - - -eliminated the necessity for frequent valve adjustments.
Jerry

Thanks again for all input. The distributor has been installed and miss is now gone. It is a rebuild @ almost $300.00 plus old core. Now, on to an oil leak around the rear main. The bottom of the engine is so dirty/oily I can't tell where it's coming from. A water leak from one of the pumps and so on. This is one odd motor, well for me anyway. Recent pics were to dark to tell much, will reshoot soon. BTW, '38 was the first year for hydraulic lifters in the V-12.