Which distributor for the Mercruiser 140?

[thompson80]

I recently repowered from a Mercruiser 120 (1980 vintage) to a newer (82-83) 140, which was originally an OMC block. After the 140 got a long block rebuild, the installer re-used all my original Mercruiser components: carburetor, fuel pump, alternator, distributor, starter. I see different distributors were used on the 120 and 140 back then. Should I look for a 140 version distributor, or will the original 120 version suffice? I plan to change the points out to a Perlux Ignitor kit, but want to know if I should change distributors first, before doing the electronic conversion. Anybody know what is best?

 

[Bondo]

Re: Which distributor for the Mercruiser 140?

I recently repowered from a Mercruiser 120 (1980 vintage) to a newer (82-83) 140, which was originally an OMC block. After the 140 got a long block rebuild, the installer re-used all my original Mercruiser components: carburetor, fuel pump, alternator, distributor, starter. I see different distributors were used on the 120 and 140 back then. Should I look for a 140 version distributor, or will the original 120 version suffice? I plan to change the points out to a Perlux Ignitor kit, but want to know if I should change distributors first, before doing the electronic conversion. Anybody know what is best?

Naw,... No reason to change the distributor housin', unless the bushin's are shot, 'n the shaft wobbles,...

There's virtually No difference to their function or output,...

 

[MikDee]

Re: Which distributor for the Mercruiser 140?

Well basically the Distributors are the same, but the (under breaker plate) advance curve, springs, & weights, may be different? I said Maybe, maybe not? You need to compare the 2 Distributors. If they are different, you might be able to just change the weight's, & springs if necessary?

 

[fishrdan]

Re: Which distributor for the Mercruiser 140?

Timing curves would be a consideration, so you would have to verify if they are different between the 120HP and 140HP, maybe, maybe not?

I have an EST ignition in my 140HP and it works fine, even thought the timing curve is much different than the original 140HP Delco distributor timing curve. The EST has more initial timing and less total advance (less total advance could hurt performance) but it's been working fine, boat rips along without issue.

The complete EST ignition is about $200 (distributor, coil, cap, rotor, wires, etc) so it's a pretty good deal, compared to the $90 Pertronix, then a coil, and wires, and,,, well you get the idea.

With the EST, the shift interrupt switch has to be re-wired to provide +12V instead of ground, and it needs a full 12V to the ignition instead of the voltage being cut back by the resistor wire. So it's not exactly "plug and play".

 

[thompson80]

Re: Which distributor for the Mercruiser 140?

I guess I have some homework to do re: distributors. I'm trying to upgrade using the KISS principle (keep it simple, stupid), but then what's another $200 after all those thousands? (insert maniacal laugh)...

The tech installed new spark plugs & points last year with the reman block, but I don't perceive that he changed out any of the other tune up/ignition parts, so I'll start with that, because some of it could be 34 years old: cap, rotor, fresh points, wires, check spark plug condition & gap, timing, dwell, idle, etc. Then the Perlux kit & coil (about $130-$171 on yeeBay currently). At the initial oil change I replaced the break-in oil with Mercury synthetic. I've already gone through two new 4-blade props (Turning Point Hustler) in an attempt to get into the proper rpm range for WOT. It was over-revving with the additional 20 hp with the original 3-blade prop, so went up in pitch PLUS the 4th blade - which was too much prop, reaching only 3800 rpm. After dropping back in pitch, she's just now kissing the bottom end of the WOT range, at 4200 rpm, so I'm hoping a fresh tuneup and the Perlux parts will give me another 200 rpm and get me up at least to the middle of the WOT range. Love the Hustler prop - she jumps right up on plane once I get through that initial bit of remaining hesitation just off idle.