Technical back two cylinders won't fire

Well Bill was kind enough to drop in last night and we got it running but before I had the valve job, the rear most cylinder on the passenger side wasn't firing properly. It turned out to be a burnt valve. Now that everything is back in place & running both rear cylinders (closest to the firewall) aren't firing. It has Bill stumped (for now) so I thought I'd do what I can and since Bill won't touch a computer, I figure someone here might have an answer. Bill set the timing (1966 Mustang 289) but he knew something wasn't right so he sprayed water on the headers and the back two remained fairly cool. Any ideas ? Thank you in advance.

 

When I get a similar issue like that, I hook my timing light to the suspect cylinder and see if it lights up. If it doesn’t I work my way back to the distributor. If it does, then I pull the wire and see if it has good spark. If spark is good, I figure I better go over the firing order again and make sure I have the wires routed properly.
I assume you put new plugs in after the head work? I ask because I knew a guy that would put everything nut and bolt in the same place it came out/off of. I’d assume he’d put each plug that he took out back in the same spot too

 

As always..... Use a vacuum gauge. If it has spark, recheck the valve adjustment. The lifters could have pumped up an hung the valves open dropping compression.

 

Valves too tight on those cylinders?

 

The ol...air - fuel - spark - timing of all three.

If it's missing one of these, it won't run..!

Now...to find the missing culprit.

Mike

 

I had a similar issue that turned out to be a missing pipe plug on a vacuum port on the intake manifold.

You might poke around and see if you find a vacuum leak of some kind, including a cracked intake. It doesn't cost anything to look!

 

Are you sure the cam isn't flat on those two cylinders

 

Along the vacuum leak lead, Ford used a carb plate in those years, that had a vacuum port in it, and at the rear. If using one of those, make sure it's connected or plugged off.

 

Good 'shade-tree method' of checking IF a cylinder is firing! (I use it myself!)
Since there was some question about valve adjustment that would be a good place to start.
Pull the valve cover.... while idling make sure...the rockers on the two cylinders are going up & down like the other rockers. (checking for wiped cam lobe)
If so then shut-it-down and re-adjust the rockers.
If still no joy pull the plugs in those cylinders and place your thumb over the hole while turning engine over to check for compression. (THUMB.not finger!)
Check plugs to make sure the electrodes ain't smashed flat and grounding out plug
Check to see IF you have spark (strong spark) coming from wires on dead cylinders.
Just work your way back(or forward on a SBF!) to the distrib.
LET US KNOW what you find out!!!
6sally6

 

I believe you installed new plug wires that you cut to fit. If you still have the old wires handy, change the two new ones that aren't firing to two old ones. This will hopefully reveal or rule out a problem with the new wires (assuming the old wires were fine and your original problem was a burnt valve and only a burnt valve).

 

Is the firing order correct?
A early 289 should be 1-5-4-2-6-3-7-8
But if it has later model cam it may be 1-3-7-2-6-5-4-8
Have you checked the compression in those 2 cylinders?

 

When did Mustangs become Hamb friendly?

 

It’s just the engine he’s using. Ya, that’s it.

 

As he has been asking questions about his Model A with the 289 in it I'd say that we can safely presume that the "Mustang" 289 in question is the one in his Model A.
Still it comes back to the basics.
Do those cylinders have decent compression?
Is there spark to the plug on each?
Firing order is the same on Ford Windsor small blocks except 302HO and 351 That shouldn't be an issue.
Wrong intake gasket set?
Plug wires burnt from contact with headers?

 

Yes. These symptoms suggest a Mustang V6 distributor is being used here. Allegedly made for Mustang's first foray into V6s simply by lopping off two back cyls on V8s just like Buick did. So the V6 distributor has the same look, feel, fit but not function as a V8 distributor with 2 dummy plugwire holes. This no doubt makes a Mustang 289 seem to run even crappier than usual. Jack E/NJ

 

What? A v8 distributor with 2 dead holes? I'm quite sure there is no such thing. All the big 3 chopped 2 cyl off their v8. (90 degree v6) And none that I know used a v8 dizzy.

 

Ford never cut the back cylinders off of a V8 to build a V6..... Ever. The first V6 was the German built motor used in Capri, MII, some Pintos. Later came the 3.8L in the mid size cars and 83 pickups and Taurus. None of these share anything with any of the V8 motors.

 

GM did. Here is the inside of an odd fire V6 distributor cap. It’s clearly a modified V8 cap, as was the distributor itself.
And relax anyhow, Jack E NJ was kidding.

 

8^)

Jack E/NJ

 

Well since the first cylinder problem was identified and corrected it seems that the second cylinder problem occurred after Bill showed up. I'd ask Bill what the hell he did to your car! LOL

 

I know I hit the same button I always do on the computer. It said I was on the HAMB, but........

 

"MOM!!!!!!!!!!.............He said the 'M' word!"
6sally6

 

Mustangs became "Hamb Friendly" when 350 & 400 Chevys did, so You can "K M Y-Block A"!!

 

Well that statement should have an interesting outcome...

 

I learned something today!

I always thought:

A Chrysler 3.9 was a 360 minus 2

And a Ford 3.8 was a 351 minus 2.