upgradeing TWIN 1985 3.0 140 horse GM engines

As most of you know, I run a 1985 wellcraft, twin 3.0 140 horse 4 cyl engines.
These are old style @ points ignition, with carbs.
Its time to rebuild the engines. Low compression { from Zero in one cyl, to 90 in the highest, with no engine reading all good pressures} , rough idle, etc, dispite our best efforts to get them right. They are old & tired for sure....
In process, I need opinions based on fact, about upgradeing the points system to electronic ignition, and if an upgrade is feasable on doing away with carbs and going to either throttle body or fuel injection.
Additionaly, if these, either or, are good ideas, where can I get the new distributer / fuel system.
Engine Ser# 6692520 & A311092 { Im guessing one was replaced at some point before I bought the boat. }

PART 2 ; In doing this repower/ rebuild, what are my options on new engines? I looked around, and can buy new for around $2500.00 but these are the new Vortec blocks. Will they be bunches of adapters, conversions and grief? Who sells direct bolt in remans? Can I go to 6 cyl power plants and still count on direct bolt ins? Should I stay with a local rebuilder just to keep it simple?

Re: upgradeing TWIN 1985 3.0 140 horse GM engines

you would save about $700 per engine by rebuilding rather than going with brand new long blocks. To me, that is not worth the savings. I would go with new. I believe the new ones come with electronic distributors, so there's half of the money back. You can get the other half back by selling your used long blocks. You only need to change the coupling depending on which style you have now (which probably needs renewing anyways)and the flywheel.
The "Vortec" thing means nothing - that's just marketing. They are the same 3.0 that Merc has been using since 1990.
A 6 cyl upgrade requires several additional things adding up to roughly an additional $5K in my head on top of longblock cost - 1. room for longer engine and fab of front mounts 2. I6 manifolds 3. carburetors and ignition systems 4. outdrives uppers of a different gear ratio. 5. maybe new tachometers depending on the ones you have now (switchable or not)

Re: upgradeing TWIN 1985 3.0 140 horse GM engines

Looking at the fuel costs 4-7 /gal. I`d build it as twin 4`s.

Re: upgradeing TWIN 1985 3.0 140 horse GM engines

Not the cheapest option but Michigan Motors sell a kit to upgrade to the genuine Delco marine grade electronic ignition. I just installed one on my 1988 3.0, and everything went well and she runs great.

3.0L Delco Voyager EST Marine Electronic Distributor Kit

Re: upgradeing TWIN 1985 3.0 140 horse GM engines

amcfall said:

Not the cheapest option but Michigan Motors sell a kit to upgrade to the genuine Delco marine grade electronic ignition. I just installed one on my 1988 3.0, and everything went well and she runs great.

3.0L Delco Voyager EST Marine Electronic Distributor Kit

Click to expand...

and that's the system that comes free with a new 3.0, making an engine rebuild a poor choice economically if one is going to upgrade ignition too
After selling the old long blocks, it would probably be cheaper in the end to go with brand new motors.

So many people looking for 3.0's without cracked blocks. good market for the used iron.

Re: upgradeing TWIN 1985 3.0 140 horse GM engines

Howard Sterndrive said:

and that's the system that comes free with a new 3.0, making an engine rebuild a poor choice economically if one is going to upgrade ignition too
After selling the old long blocks, it would probably be cheaper in the end to go with brand new motors.

So many people looking for 3.0's without cracked blocks. good market for the used iron.

Click to expand...

Ayuh,.... The local Machine Shop 'round here is payin, a couple a hundred for rebuildable core long blocks...

basically $100. for a core head, 'n $100. a core block... yer locality may vary....

Re: upgradeing TWIN 1985 3.0 140 horse GM engines

Bond-o said:

Ayuh,.... The local Machine Shop 'round here is payin, a couple a hundred for rebuildable core long blocks...

basically $100. for a core head, 'n $100. a core block... yer locality may vary....

Click to expand...

I bought a new 3.0 from michigan motrz in 2007, the upgrade to new dist kit cost only $100.
I had to buy a new fly wheel and engine coupler since my old engine used the old style coupler and 12.75 fly wheel.