440 has 2 cylinders not firing, #5 and #8 after installation

[R. Everett]

I have a 440 has 2 cylinders not firing, #5 and #8. It has a MSD ready to run for a distributor and new plugs. Engine was recently refreshed but when I fired it up and the paint on the headers for #5 and #8 did not melt off. Checked the temps at the headers and sure enough they are running cold. Swapped plugs and plug wires from both and still will not fire. Used a spark checker and both seem to have spark. Checked compression it was 125 psi. Seems to have all the ingredients to fire but will not. Any thoughts?

 

[lewtot184]

look at the intake manifold and see if 5 and 8 are getting fuel off the same plenum/carb bores. could be the carb is very fat and causinig a distribution issue. too rich will cool the exhaust temps. other than that just go over the electricals with an ohm meter to make sure everything is working. if you had 2 dead cylinders the engine should really run awful.

 

[Pops1967GTX]

When you pulled plugs, did you notice any damage, fuel soak oil?

 

[R. Everett]

The plug looked fine but did have fuel on it. No oil

 

[miller]

Checked compression it was 125 psi.

Compression seems a little low, but that depends on the build. Those two cylinders have the same compression...125?
If the plug wires/spark plugs check out, could be something in the distributor itself...almost have to. Maybe the cap??
How does the spark look, compared to the others?

 

[68gtxman]

You need fuel, air and spark to fire. So you have fuel. You must also have air if you got the fuel (no rags inside the intake manifold?). Then the problem must be spark. Try swapping plug wires and see if the problem follows the wires.

 

[khryslerkid]

Plug missing off the back of the carb or on the manifold vacuum port?

 

[PurpleBeeper]

Yeah, I'm with lew & krylser....fuel mixture off....maybe an intake manifold leak on those two cylinders? You have a "range" it will fire up with. Too much air or too much fuel & "no fuego" (no fire)....and maybe check those plug wires with a grounded extra spark plug.... crack in the distributor cap?

 

[Daves69]

?? You have verified the firing order.....

 

[R. Everett]

Compression seems a little low, but that depends on the build. Those two cylinders have the same compression...125?
If the plug wires/spark plugs check out, could be something in the distributor itself...almost have to. Maybe the cap??

?? You have verified the firing order.....
View attachment 613418

Will recheck tonight, thanks

 

[HALIFAXHOPS]

Could be something in the distrib also they are 180 out in the firing order.

 

[R. Everett]

Will recheck tonight, thanks

Changed plug wires , cap and rotor, plus checked for vacuum leaks and still the 2 cylinders will not fire.

 

[oldbee]

2 bad spark plugs?

 

[1967coronet440]

You obviously have air and fuel, only thing left is spark.

 

[oldbee]

Valves sticking open?

 

[moper]

Sounds like you have compression (low but enough to fire, and hopefully similar to the other holes) and spark... So there's only fuel you're short IMO....lol.

 

[Garys1969RR]

Try swapping in another distributor.

 

[eldubb440]

move all the wires 1 position either direction, rotate distributor to compensate...…… see if the same 2 holes are missing

I was thinking 2 wiped intake lobes, no valve train noise?

 

[miller]

He had said, compression in all 8 holes were about the same. I'd think a wiped lobe would show up, on the test.

 

[Garys1969RR]

Seems odd, because 5 and 8 are directly across from each other on the distributor. Maybe try swapping those 2 positions where the wires plug in to the dist, but leave the wires hooked to the same plug they are on.