Pertonix conversion- timing?

[yago]

I have a aq120b volvo penta 4 cylinder. Bought the boat for a song. The dist was converted to a pertomix ignition. Points are gone. Dist was apart, wires, alt. etc. When i pull up Number 1 cylinder to tdc. The dist button is not aligning to number 1 post. No problem, turn dist till it points to it. Problem is the firing on the pertonix is not right. I pulled the coil wire, ever time the coil fired, i our a drop of paint on magnetic sleeve on dist shaft. Now have four points of fire. When i align the marks on the sleeve to the pertonix module, the rotor is pointin between two post. Seeems the rotor and , and coil should fire then, they dont. Am i doing something wrong, Please help. Just need to find number 1 to fire at tdc. Then i can finish up.

 

[Don S]

Re: Pertonix conversion- timing?

You have to have #1 cylinder at TDC of the compression stroke. You could be 180 out.
Remove the spark plugs, turn the engine over by hand with your finger over the #1 spark plug hole. Turn the engine in the normal direction of rotation till you feel compression building, now slowly continue turning till your timing marks line up. Now, you are at #1 TDC on the Compression stroke.
Now put the distributor in place with the rotor aimed at the proper mark and make sure your plug wires are on in the proper sequence.

 

[WizeOne]

Re: Pertonix conversion- timing?

I had that problem with my pertronix unit. I actually cut a hole in the top of the distributor cap and put a timing lite on the rotor while the motor was running. It was firing well past the number one post.

I had to slot the holes in the module plate and rotate it until the rotor fired on the post. You also want to check the gap between the magnet ring and the module. It should be about .030

This issue you have is called a phasing problem. I really think Pertronix screwed up and I speculate that there are a lot of them out there running out of phase.

 

[Fishermark]

Re: Pertonix conversion- timing?

I've never heard of such a problem - not saying it can't happen, but I would suspect something hasn't been installed correctly. Is the magnetic sleeve located correctly and pushed all the way down? If not, that would throw the firing out of whack. Here's the instruction sheet for Pertronix - I don't know if it covers your model or not, but it gives the general idea: (Look at items 13 and 14)

 

[WizeOne]

Re: Pertonix conversion- timing?

.... I've never heard of such a problem - not saying it can't happen, but I would suspect something hasn't been installed correctly.....

Fishmark, have you ever drilled a hole in the cap and watched the firing point with a timing light?

In my case there was no doubt about the installation. The module was rivited to a new base plate and the module was over .090 away from the magnetic ring. The mounting holes in the supplied plate were pre-drilled by pertronix. There was only one way the magnetic sleeve could fit on the distributor shaft. There were no options.

This was all on an otherwise unaltered Prestolite Mechanical Advance marine distributor. The only reason I look further was that my motor was running crappy and I could see arcing tracks on the inside wall of the distributor cap, between the two cylinder posts. That's why I drilled the hole in the cap to see what was going on.

As I mentioned I had to elongate the mounting holes so I could rotate the module plate then I had to drill the module rivits, elongate those holes and move the module closer to the magnetic ring. Then I had to retime the engine.

It was quite exasperating and the Pertronix tech was absolutely no help.