Topic: #4 pipe warm... but not hot...

[DJ_AX]

'75 550.. stock everything 'cept 4 into 1 mac pipes.
All timed and tuned including carb sync.
While everything appears to be ok.. running well, plugs look ok... the #4 pipe is not getting nearly as hot as the others. I'm sure it's firing as it wants to die if I pull the wire off while it's running. And like I said all the plugs looks a nice tan.
I do plan on brand new plugs but the stores are all closed right now.

So ... why is the #4 pipe warm... but not hot?

[TwoTired]

I'm sure it's firing as it wants to die if I pull the wire off while it's running.

Don't be so sure, they can idle on 3 cylinders.  Pulling off a spark lead affects two cylinders, not just one.

So ... why is the #4 pipe warm... but not hot?

I'll guess, an impeded pilot jet.

[Greggo]

How old are your plug wires?  May be time to snip a little bit off the end of that plug's wire where it enters the cap.

[DJ_AX]

How old are your plug wires?  May be time to snip a little bit off the end of that plug's wire where it enters the cap.

Heh heh... probably originals .. already snipped a lot.. in fact on number 2 it was too short so I snipped it a couple inches from the coil and spliced a new wire in. The inside of the wire was goop  ... all the way up!

[Greggo]

How old are your plug wires?  May be time to snip a little bit off the end of that plug's wire where it enters the cap.

Heh heh... probably originals .. already snipped a lot.. in fact on number 2 it was too short so I snipped it a couple inches from the coil and spliced a new wire in. The inside of the wire was goop  ... all the way up!

Yeah, plug wires are kinda important   Sounds like it may be time to replace 'em even if they're not the real problem.

[Duanob]

I'm sure it's firing as it wants to die if I pull the wire off while it's running.

Don't be so sure, they can idle on 3 cylinders.  Pulling off a spark lead affects two cylinders, not just one.

So ... why is the #4 pipe warm... but not hot?

I'll guess, an impeded pilot jet.

+1

[DJ_AX]

Yes that's what it was! Thanks...
When I looked at it the last two times (and it looked spotless) I neglected the thru hole. With a guitar string... I pushed out a tiny glob of gunk... smiled and said "oohhhh yeaaahhhhh"

Purring at all RPMS now.