How to set the distributor?

[Wet Wonder]

Hi, I have a single inboard Mercruiser 351 233hp 2bbl on a 25 foot Trojan Cabin. I'm putting in a new distributor w/ elec ignition and manual spring advance (no vacuum). It comes with three sets of springs and three different advance limiters.

The first spring set advances pretty quick, 24 degrees at 2000 rpms. The second springs are slower, 10 degrees at 2000 rpms. The third spring set is 3 degrees at 2000rpms. Any opinions on which set I should use?

Then there are the timing advance limiters. The first has a max advance of 12 degrees. The second 16 degrees. The third 20 degrees. Anyone suggest which I should use?

I think idle timing is supposed to be around 8 or 10 degrees for this motor. I have to check the manual.

Thanks very much . . . WW

 

[bruceb58]

Re: How to set the distributor?

Depends on what total advance needs to be for your engine. Your manual will tell you. Usually there is a graph that shows the stock curves. Since you have a heavy boat you may want to be on the conservative side with slope on the low side rather than the high side.

 

[WizeOne]

Re: How to set the distributor?

I think idle timing is supposed to be around 8 or 10 degrees for this motor. I have to check the manual.

It's 10 deg btdc but that manual should show you the appropriate curve and totals for that 351w.

 

[Wet Wonder]

Re: How to set the distributor?

I just looked it up.

Timing at idle = 10degrees BTDC.
WOT RPM = 3800-4200.

Timing advance:

Min = 0degrees at 1200rpms, 18degrees at 2000, and 22degrees at 4000

Max = 0degrees at 1000, 20degrees at 1500, 26degrees at 4000


So what springs and limiters should I use?

 

[bruceb58]

Re: How to set the distributor?

Well, you can take your pick of the two limiters..either 12 or 16.

As far as the advance springs, the 2 fast ones seem too fast. You could put the middle one in and set the base timing a little lower to make sure it reached the range of advance that is in your book.

Another option is to take the distributor to a speed shop and have them put in the proper springs to get the advance curve you want.

 

[Wet Wonder]

Re: How to set the distributor?

Thanks for everyone's help. I ended up calling Pertronix, where I got the distributor. I learned that the distributors are each set for the specific model motor. So I bought the one for the Merc 351Windsor 233hp, which is set exactly for the spec power curve. Pretty good I think - a complete distributor assembly, w/ electronic Ignitor II ignition, rotor, cap, all complete, for $225. Just pop it in and it's ready to go. I don't think there's a better boating deal out there.

 

[mkast]

Re: How to set the distributor?

http://cgi.ebay.com/ebaymotors/ws/e...2486798891&viewitem=&sspagename=STRK:MEWAX:IT

 

[Wet Wonder]

Re: How to set the distributor?

That's a good deal, but its the stock prestolite distributor, and it doesn't fit the marine merc windsor motor. The Pertronix distr w/ Ignitor II can be had at www.carshopinc.com for $225:

http://pertronix.carshopinc.com/product_info.php/products_id/86990/D231800

 

[mkast]

Re: How to set the distributor?

but its the stock prestolite distributor, and it doesn't fit the marine merc windsor motor.

It fit the 351 Windsor I put it in.

 

[WizeOne]

Re: How to set the distributor?

It fit the 351 Windsor I put it in.

This is what was posted on that ebay auction:

"We've been told by people who have purchased these that they will fit a Ford 429 or Ford 460 and by changing the drive gear they will fit a Ford 351 Cleveland. Double check the numbers and check with a dealer to be sure."

I hesitate to buy something when the seller cannot even attest to its fitment.