78 country squire engine misfire

Hmmmmm.
All good points and I appreciate all the feedback.
I have warmed the engine in the garage until the choke opened fully and it still ran smoothly.
I'm thinking the heat in the engine compartment might be causing the ignition to fail. Even though I replaced the coil, I am going to put a flamethrower coil and distributor in.
I already ordered these parts or I would have reseRched the duraspark.
I have had good luck with Pertonix, so let's see what comes of it.
I will hopefully get it installed and a test drive before I have to leave town for a couple weeks.
Anyway, I will post one way or another.
Thanks,
T
Btw, I did inspect the aluminum spacer plate and found it warped. I filed it flat and made certain I had the special EGR type gasket between it and the manifold.
I. Also, have sprayed starting fluid around all vacuum lines and fittings. Negative.
T

 

The coil, and the pick-up coil in the dizzy, would be the biggest culprits. But I've also seen engines that open up vacuum leaks once they get hot. So, even with the checks you've done, drive it until it begins misfiring, then spray again, but use carb cleaner. It is not as volatile as starting fluid, and it makes the engine run better when it's combusted. Do that before you chase the lightning.

 

In the meantime, I'll look up the ohms specs for the coil and pick-up coil.

 

Has the ignition control module on the driver's side fender ever been replaced? Sometimes engine heat makes these do strange things when they are beginning to fail. These are a common point of failure.

 

Wow,this sounds exactly like my problem with my '73! Although there are timing issues too. I'll have to look at that spacer again,though it was OK last year with the rebuilt carb install.

 

Remember, his is electronic ignition versus your point-condenser ignition, as well as other differences. But, that spacer to intake gasket is the same design and materials on all EGR-equipped '70s Fords. Even if it looks 'good,' perhaps cleaning and flattening the bottom of the spacer and putting a new gasket under it would be excellent preventive maintenance.

 

Yeah,I know,I had a '77 Country Squire back in the mid-'80s. Hall effect,Hydro-Boost system,etc.,but all it ever wanted was brakes & tires.

 

Really,though,how is an "exhaust leak into the carb" different from the EGR sending exhaust gases into the manifold?

 

Contrled metering versus uncontrolled leaking. EGR gases dilute the air fuel mixture, so too much is like a lean run condition.

 

Wow,OK. I hope the parts man can get me the appropriate gaskets,then I'll have it apart and (most importantly) evaluate and recondition the notorious plate. We don't use any sealant of any kind on these gaskets???!!!

 

The coil resistance for '78 and newer DS-II coils is 1.13 to 1.23 ohms primary and 8K to 13K ohms for secondary, measured from either primary post to the center tower. Check the resistances when the underhood is cold iron, then you should drive the car with a DVOM on the seat next to you, and when the engine begins misfiring, pull over immediately and pull the connector off the coil, then check PRI and SEC resistances. There should not be much, if any, change in resistances, but if hot resistance (especially on the SEC) is lower by 10% or more, you should replace the coil

 

So I got the gaskets from the local Ford Dealer Parts dept. The first one is a D5ZZ-9C477-A. This is the one with the plastic inserts for the studs and it is the thick one,with no extra passages. This goes under the carb,doesn't it? The other one is a thin gasket D3AZ-9447-B which I would think would go under the spacer.BUT! The diagram in the manual shows EGR passages on the passenger side of the vehicle,and the gasket has just a slot on the left side (gaskets are each marked "FRT UP" which I take to mean what it says. Seriously, the Ford picture shows exhaust gases coming up through a hole in the manifold,right side and through the spacer to the EGR and back to where it has been metered into the mixture. Maybe it'd be better to just eliminate the EGR and the spacer,but wouldn't that screw with the function of the throttle and kickdown linkages? Or is the D3AZ gasket that supposedly routes the exhaust gases the wrong one for the '73 400? I might be able to see things more clearly when I remove the carb & spacer. I've put so much work into this carb setup already,including all choke stove parts,total carb rebuild,resetting the idle mixture this week...Oh well. I don't recall exactly what I did a year ago when I got the rebuilt carb back--I utilized the gaskets the rebuilder provided,but why would I remember now what they were? And with a magnet, I couldn't verify if I have the awful aluminum spacer or the cast iron one! Anyway, the work is scheduled for Wednesday...

 

Weight. That's what'll tell you which spacer you have. Cast iron will be hefty, and aluminum will feel very light.

 

I guess what I was saying was that with the whole deal assembled,my magnet went right there,but what was it attracted to? The spacer or the manifold? Or both? Once the spacer is off the manifold,obvious to tell which metal it is. My main worry is that the lower gasket has a space for exhaust gases that doesn't match the picture in the manual--it's on the other side,if I am to believe the "FRT UP" marks on the gaskets.

 

OK,so now I've got it apart. The rear stud on the driver's side was welded to the aluminum spacer (bimetallic corrosion),so lots of penetrant and wrangling got the spacer off,though the stud is still stuck in the manifold. The spacer is corroded beyond repair--obviously been on there since 1973. The return passage of the EGR was completely clogged. The picture in the manual with the exhaust passage on the passenger side must've been for a different manifold--the lower gasket I got from Ford matches the exhaust passage in my manifold,which,by the way is full of soot and crap. My decision now is to either look for a cast iron replacement EGR spacer or (Plan B) to discard the total EGR system. I am leaning toward plan B. I might need different studs, as the carb would sit lower. OK,back to work--gotta clean up that manifold!