2.25 not firing 3&4 ?

[Lance]

I am working on a 1967 109 staton wagon. It has the stock 2.25 engine. It was running great then out of nowhere it started running only on #1 & 2. If I remove the plug wires on 3&4 cylinders it doesn't make any difference. I have tried almost everything I can think of to make it run on all 4. The head is rebuilt...new valves,guides,seals,& exhaust seats. Honed the cylinders & installed new rings. Adjusted the valves like the book says. I have compression & spark. I have two distributors...the original Lucas with a pertronics & a new one with points(this is the one that was in the engine when it started running bad). Nothing changes with either one. I static timed it like the book says, TDS on flywheel both valves closed dissy rotor pointing to #1 BUT when I put my adjustable timing light on it I have to move the knob on the timing light 40 degrees to see the timing marks????
Could the gear between the cam & dissy jump a tooth? Also what is the grub screw & what does it do?
I just about out of ideas.

[jopa]

poor running

Lance...Ive read your post elsewhere too...few things to consider. Its either in the distributors or the cam/crank timing..
Check to make sure you are getting spark at the 3rd and 4th plug- pull them- connect to the wire and turn the engine over by the ignition- is there any spark?...if no then its the distributor or leads or plugs...

If yes- then look at your timing- not the light on the crank but---cam to crank.
Take all the plugs out and by hand turn the the engine over slowly- are all of your valves opening and closing as they should? Next then check to make sure the cam to crank are properly timed to each other

- use a skinny screw driver or piece of coat hanger to feel the #1 piston rise on the compression stroke- watch your valves carefully- exhaust valve should not open until the piston has reached the top- not before and not after...this will tell you if the timing chain has jumped a tooth from stretching...it will throw all your timing off. The chains do stretch...Good luck- John

[siii8873]

I had this same problem. It was blown head gasket. If you have a spark on both cylinders check your compression also, you may find it low on 3 & 4 if it is a blow gasket.

[SafeAirOne]

...pull [the plugs]- connect to the wire and turn the engine over by the ignition- is there any spark

Note that you have to ground the outer spark plug shell in order to get a spark.

[Broadstone]

I had this same problem. It was blown head gasket. If you have a spark on both cylinders check your compression also, you may find it low on 3 & 4 if it is a blow gasket.

I agree. If both plugs fire its the head gasket. I too had the same problem.

[Apis Mellifera]

In your testing, have you substituted the distributor cap and/or the plug wires. You have confirmed that you've got the firing order correct?

[Lance]

I have tried new wires,car & rotor. I am starting to believe that the timing belt has jumped. In the manual it says/shows the dissy drive gear 20 degrees from a bolt hole on the triangle that hold the dissy. I have 40 degrees. 20 degress too much. Could that cause these cylinders to not fire???

[Apis Mellifera]

No timing belt in a Series. It's a chain. For it to jump, there would have to be some pretty unusual/destructive circumstances and none of the cylinders would fire. What's pretty common is to reverse 3 and 4 when installing the plug wires.

The drive gear is located only because the distributor only goes in one way and to make sure the vacuum advance unit doesn't foul throughout the adjustment range. In fact, you could rotate the distributor 180 degrees and as long as the wires are in order, the truck will run. It doesn't care whether there's 20 or 40 degrees, the engine wants the spark at the right time. In your case, the distributor would just need to be rotated 20 degrees in "the right" direction, but again, those references are arbitrary.

For kicks, flip the 3/4 plug wires. If that doesn't work, make sure they're sparking. Next, I'd check compression. If the valves are too tight or the head gasket is blown, that will show the compression loss.

[Lance]

The head gasket is brand new, just rebuilt the head. I have 120 psi on all four cylinders. Rings are new. I have compression with plugs out of all the cylinders & with plugs in except for the one I'm checking. I have compression with the motor running & the compression tester on. I have adjusted the valves as per the manual, they are all about .010/.011. They look like they are moving when they should. I am getting spark to those plugs.
I'm just not sure how could it fire 1&2 but not 3&4. This problem started all by it's self. one day it was fine the next day no worky. The head needed rebuilding anyway so I thought now is the time so I could check the head gasket.
Thanks for the ideas...keep um comin. I'm going to find it!
I'm thinking of pulling the timing chain cover & check the chain, the front main seal leaks anyway so maybe I can kill two birds with one stone.

[SafeAirOne]

Don't know if you ever got an answer, but the grub (skew gear bush retaining) screw, which threads into the block under the oil filter adapter, keeps the skew gear correctly engaged with the gear on the camshaft and prevents any movement of the skew gear assembly in its bore.

Generally, in order for the skew gear to become disengaged from the gear on the camshaft, the whole skew gear assembly would have to rise up in its bore about 1/2" to 3/4" (along with the ignition distributor assembly) then settle back down in place and re-engage the oil pump drive shaft splines.

IIRC, without a grub screw, the skew gear naturally wants to rise when the camshaft turns because of the cut of the skew and camshaft gears.

[Lance]

I never did get a answer to the screw gear....thanks so much. That helps a lot. Probably not that if it would have to move that much. Think I will pull the timing chain cover next.
Thanks for the pic & info. Big help!
I have only owned this a few months, need to learn.

[bkreutz]

I don't know what pulling the timing cover will tell you, any problem with things in there would affect all 4 cylinders the same, the cam timing would either be correct or incorrect for all the cylinders. Looking over your last post, you say you have compression on all 4 cylinders and spark on all 4 cylinders. That only (at least in my mind) leaves 2 things, spark at the correct time (re read some of the earlier posts about crossed plug wires) or fuel. If you have fuel, compression and spark at the proper time it will fire. Is it possible that something in the intake is blocking the back two cylinders preventing the fuel/air mixture from getting there? The reason I ask is that years ago I ran into a similar problem and found a shop rag had been left in the intake manifold during a repair and it was blocking off a couple of cylinders.

[Lance]

I just put the manifold back on a couple weeks ago when I put the head back on. I didn't run a wire or anything through the manifold so I quess there could be something in there but I think I would have noticed plus this problem started all on it's own. I might take it back off, at this point it won't hurt & isn't that hard to do. I agree that pulling the timing cover may not help but I really don't know what elase to do Plus I don't understand if I set everything on TDS #1 then start the motor and put my timing light on it I don't see any timing marks. I thought I should see TDS on the flywheel? I have to adjust my timing light 40 degrees to see the timing marks???

[SafeAirOne]

I agree that it's unusual to have a sudden MECHANICAL issue where the rear 2 cylinders don't operate.

Not to be insulting, but are you sure the timing light is on the #1 plug wire and the firing order is correct? If you put the timing light on the other wires, does the timing mark on the flywheel come closer to the pointer?

I still think it's an electrical issue in the primary or secondary ignition circuit/components.

[Apis Mellifera]

The dynamic timing may be near 40 degrees. You have initial static timing, which is what you measure on the crank pulley or flywheel, and you have the mechanical timing provided by the distributor. To find out what the distributor timing is you take the points plate off and look at the weights. There will be a number stamped on them, say 15. Multiply that by 2 and add the static timing of, say, 10 and you'd have 40 degrees total. It's possible the small springs inside the distributor broke, producing max mechanical advance at all times.

http://www.jcna.com/library/tech/tech0015.html

That might help my explanation.

That said, as was mentioned, given the info you've provided, anything timing related that suddenly happened would have caused all cylinders to misfire. Humor us and simply switch 3 and 4 plug wires to see if that does anything. If that doesn't help, and as you said, you have spark and compression on 3 and 4, it has to be inlet related. I can't think of anything else that could produce the same results based on your tests.

The valves are working
The valves are gapped
There is spark
There is compression
The front two cylinders are working properly
The misfire was sudden
The firing order was checked

This doesn't add up to a misfire on 3 and 4 - I'm stumped.

Just to be sure, your wires should be CCW 1-3-4-2... You can get it backward and still have two cylinders correct.