Firing order

[William S.]

I am changing the plug wires on my 1969 350/300. I don't do it often so I do them one at a time to make sure I keep the order right. When I got to number 4 it went into the number six slot in the distributor. I traced number 6 to the number 4 slot, so my firing order is 1-8-6-3-4-5-3-2 instead of 1-8-4-3-6-5-3-2. The car ran fine, occasionally a little rough at idle but nothing more. I'm going to correct the issue, but should I have had some symptoms with something like this?

[Richard G.]

Re: Firing order

Yes you should have noticed it ran like a Ford..

Get it back on the road and enjoy the smoothness of the factory motor.

[Richard M.]

Re: Firing order

FYI a typo.... 1-8-4-3-6-5-7-2

I'm baffled how it could run without backfiring. I don't think 4 and 6 have the same valve to piston timing proximity.

Or maybe they do.

I suppose looking at the #4 lobes and #6 lobes of a loose camshaft could tell.

[Mark E.]

Re: Firing order

With #6 firing 90 degrees early, it's in the middle of the compression stroke. With #4 firing 90 degrees late, it's already half way down the power stroke. If this happened, the engine would run terribly, if at all.

If it ran ok before, my bet is the firing order was correct and you just made mistake checking them.

Correction: #6 is firing 180 degrees early, at the end of its intake stroke with the intake valve open. This could cause the air/fuel charge backfiring up the intake. #4 is firing 180 degrees late, at the beginning of its exhaust stroke with the exhaust valve open. This could cause the charge to flame out the exhaust.

[William S.]

Re: Firing order

Yes. That was a typo. It didn't backfire. As I said it ran ok. Runs great now. The improvement probably because of new plugs and wires.

[William S.]

Re: Firing order

I did them in order and when I took off number 4 it was plugged into the wrong hole. Can't have been a mistake. I changed them and it runs better now. It's got new plugs and wires so it should run better. The little roughness is gone. Anyway thanks to everyone.

[Mark E.]

Re: Firing order

Maybe an example of what happens when a beer cooler is in the garage?