318 Chrysler IB

[jerryjerry05]

My friend has a 80's Chrysler 318
The distributor took a dump.
He bought a replacement. It has the vacuum advance hooked up on the side.
The old didn't have it.
Should he hook it direct to a plug on the intake or a vacuum line on the carb?

I had an old I/B with twin 350 Chev's and it came with car dist. with the vacuum hooked to the intake.
How should it be hooked???
I say to the intake. His neighbor says to the carb. He says the intake will have too much vacuum.
Thanks.

 

[jerryjerry05]

Vacuum advance??/

The distributor took a dump.
He bought a replacement. It has the vacuum advance hooked up on the side.
The old didn't have it.
Should he hook it direct to a plug on the intake or a vacuum line on the carb?

I had an old I/O Volvos with twin 350 Chev's and it came with car distributors with the vacuum hooked to the intake.
How should it be hooked???
I say to the intake. His neighbor says to the carb. He says the intake will have too much vacuum.
Thanks.

 

[Bondo]

Ayuh,.... It's an automotive distributor, he shouldn't use it at All,...

Boat distributors use fly-weights, or electronics,.... not vacuum,....

What motor has he got,..??

 

[Bondo]

Ayuh,.... Just answered this in the Volvo forum,.....

Now they're merged,....

 

[jerryjerry05]

He's got it in and running.
He bought it before he asked for help.
I told him he needs to hook it to the intake.

He asked me to come down and make sure the plug wires were on right and when I got there I found out what he bought.

 

[wrench 3]

If it's an automotive distributor it's not vapor proof and could be an explosion hazard!

 

[jerryjerry05]

Got the right response from Rick. My friend has a 80's Chrysler 318
The distributor took a dump.
He bought a replacement. It has the vacuum advance hooked up on the side.
The old didn't have it.
Nor will any Marine ignition distributor. The diaphragm vacuum advance is not only unnecessary, but it will serve no purpose for a Marine engine that produces very little manifold pressure (vacuum).
In addition, the automotive advance curve will be incorrect for his Marine engine.

Should he hook it direct to a plug on the intake or a vacuum line on the carb?
​

No... in order to be USCG approved and to protect his engine, he needs a Marine ignition system.

I had an old I/B with twin 350 Chev's and it came with car dist. with the vacuum hooked to the intake.
How should it be hooked?? I say to the intake. His neighbor says to the carb. He says the intake will have too much vacuum.
​

Just the opposite.
At all times when above hull speed, the Marine engine is under load.
With the throttle plates open for heavy engine demands (beyond what the automotive engine would require for similar speed), this prevents any substantial manifold pressure that would bring the advance further.

Even if the diaphragm vacuum advance did bring on more advance, this would be during loads when we least want more spark lead.
More spark lead would most likely cause detonation damage.

He needs to bite the bullet, and buy the correct ignition system.
Like said, the advance curve is most likely incorrect for his marine engine.
Short of overheating and low to no oil pressure, ignition induced detonation is the Marine engine's worst enemy.
It can take out the tops of pistons, and can take out valves along with it. And it will do it with little warning to boot.

I removed the pipe plug and the motor seemed to have a lot of vacuum??
​

Sure, if no load on the engine, it will produce similar manifold pressure to that of a car/truck engine. But these marine engines do not operate above hull speed with light loads.
A heavy load demands that the throttle plates to be more fully open.
When the plates are more open, manifold pressure diminishes rapidly.

Marine loads are significantly greater than auto loads given the same speed.
In order to compare to automotive, the car/truck would need to be pulling a heavy trailer up a never ending hill, and in a higher than usual gear.

.
What would it do if it's left unhooked? (I think I can answer this) timing won't advance and cause big problems.
​

No... this will still have a mechanically advancing system using flyweights and flyweight return springs.
The diaphragm vacuum advance is used on auto engines during manifold pressure that says it's OK to advance further.
It also prevents the auto engine from back-firing during deceleration, of which the Marine engine never experiences.
Trust me... the Marine engine will see no real benefit from diaphragm vacuum advance.

The owners one of these guys who thinks "I can fix it, I don't need to ask any questions" Until it's past the point of no return.
​

And he may end up at the point of no return sooner than later, if he allows this system to cause detonation damage.
I would NEVER install an automotive ignition system on a Marine engine.
It just isn't worth it!

 

[Bondo]

Ayuh,.... Ricardo is always wordy, 'n usually Right,.... Yer bud needs a different distributor,....