Dropping a cylinder

[Tacklewasher]

So I've finally figured out that I'm dropping the bottom starboard cylinder.

On muffs in the driveway, the RPM moves up and down noticably. So I tossed a timing light on and found the one cylinder firing/not firing in concert with the RPM (and sound) changes.

Pulled the plug and it looks fine. Quick compression check should the cylinder about 10psi higher than the other three. Took the ground off for the coil, cleaned it up and put it back on with no change.

Gonna grab some new plug wires (they look pretty old) and a spark tester to try to see if it's the coil not firing or something in the cylinder causing it (I figure if it will light up a spark tester grounded, then it's not the coil).

Any other suggestions?

Thanks

 

[jtexas]

Re: Dropping a cylinder

You can switch the coil with another cylinder, problem moves with the coil, bingo. if the wires reach, won't even have to pull 'em off the engine.

 

[Tacklewasher]

Re: Dropping a cylinder

Hmmm.

Good idea. Try that tomorrow night.

 

[Tacklewasher]

Re: Dropping a cylinder

Took another look.

The coils are hard wired in. They are not the kind with the trigger wires on a post (except one I swapped last year). Aside from cutting wires, I think I'm back to my original idea.

 

[KYHunter2]

Re: Dropping a cylinder

A spark isn't allways a good spark.

Will it jump 7/16 " gap with a bright blue spark, and an audible cracking sound ?

You can do a resistance test on coils.

Very simple, its in your manual.

KYHunter

 

[emdsapmgr]

Re: Dropping a cylinder

Try swapping the power packs and see if the problem moves to the other side.

 

[Tacklewasher]

Re: Dropping a cylinder

Very simple, its in your manual.

Which page? 8)

(j/k. I've got a manual and I'll find the page)

Gotta buy a spark tester (I own one, but no idea where it is). Of course I should have been doing this last weekend, not two days before the long weekend.

If it is electriical, is it more likely to be the power pack or the coil? I'm thinking the coil either works or it doesn't. But I'd like to try the simple things first.

 

[jtexas]

Re: Dropping a cylinder

You can't swap the ignition coils? What do you do if one goes bad and has to be replaced?

 

[Tacklewasher]

Re: Dropping a cylinder

You can't swap the ignition coils? What do you do if one goes bad and has to be replaced?

You buy a kit that includes the trigger wire with a pin on the end. You pull the old wire out of the conncetor and put in the new one.

To try to test it, you pull the pins out of the connector, swap them so they go in the other holes in the other side of the connector and switch plug wires.

Of course, in the process you pull a wire apart leading you to think the issue is a corroded wire in the connector.

Here's the replacement kit that might make it clearer.

coil kit

 

[jtexas]

Re: Dropping a cylinder

ok, I knew that, also knew those plugs are a *****, sorry, thought you meant something else. carry on.

8)

 

[Tacklewasher]

Re: Dropping a cylinder

Well. Turned out to be a power pack. Picked up a new one and took it for a run last night. Ran better than ever.

So the carbs are done, the ignition is working, it's been seafoamed. Must be time to put it away for the winter

So. Is there a problem running this old beast at over 5500 rpm? I can get to just shy of 6000 and am thinking of trying a different prop to get more speed.

Then it's time for the jet leg and fishing the Fraser.

 

[Cricket Too]

Re: Dropping a cylinder

Just shy of 6K is the perfect spot for it, it will be nice and happy there.