Rebuild or Replace
 

OK here's the situation....

The Cig 20 has (what seems to be) a mostly original SBC with original exhaust manifolds. Blcok casting numbers take it to early to mid 1970's. The engine starts every time and runs fine pushing the boat to right at 50 mph with no issues. RPM's are unknown as that's another project for the off-season. If I use Bam's HP calculator it puts me only at 150HP. Could be, compression was right at 110-120 on all cylinders. I'm not sure how tired the engine is.

For background, I want ultra-reliability and longevity, i.e. turn the key and go. No tweaking jets, timing, reading plugs, etc. Would like to see 350-400+HP

It seems there's several options. Do I...

Pull and rebuild the existing engine (new accessories and exhaust)
OR
Find a low hour take-out complete engine
OR
Purchase a new small block merc engine
OR
Have a shop build a SBC (new accessories, exhaust, etc.)

Budget is a factor and obviously impacts the decision. For effect, let's assume $3-4k including everything; engine out/in ready to go.

I would probably purchase a new merc motor. Then you would have a definite warranty...and you would KNOW whats in it, and that it wasnt abused. If you buy a used one, your rolling the dice. As for making 400 hp with the motor you have...I would bet that your motor has sh*t heads, and cast internals. Buy the time you buy quality true 400 hp parts, and have all the machine work done...you'll be significantly over your budget sir. :drink:

get a new 383 or 350mag and call it a day

You would have a hard time getting a true 350 horsepower small block built properly for marine use with exhaust, carb etc for maybe $5000, never mind taking it out and putting it back in, tuning it, upgrading your fuel system etc.

Bill Koustenis
Advanced Automotive Machine
Waldorf Md

I don't think there is any way you are going get a 350-400hp SBC that is reliable for 3-4k including the install. IMO, you will need close to double that.

A Merc factory long block is nearly $3-4k, and that's JUST the long block. I will echo what others have said, you won't be able to do it for $3-4k. I know it blows, but I just went through a similar situation. I would also bank on a lot, if not all of the old parts are shot or worn out and can't be re-used.

The minimum for a turnkey Merc 350 is in the $5000-7000 range and that doesn't include take out /install cost.

If you can get the motor in and out yourself that will save a good chunk of money. It may be intimidating, but it's not impossible. I had my motor out single handedly in 5 hours and I was taking my sweet time. That was the time from initial wrench turn to the motor on a stand in the garage. It wasn't rocket science and now that I've done it I'd do it again in a heart beat.

Purchasing a turnkey Merc motor is the easiest.

Purchasing a bare bones Merc long block may be the cheapest.

Going with a custom built motor will most likely yield the most satisfaction. Custom doesn't have to mean exotic either.

I wish you all the best.

How about a ZZ383 (425hp) crate motor from Chevy. A buddy installed a pair of them in his 26 Sutphen 5 yrs ago. Presently at 330 hrs (mostly above 4500 rpm) No issues at all. At the time they were $4850 ea.

Great deal

OK, OK. So what is the better sacrifice? Budget, turn-key reliability or HP?

I've been around boat engines for some time doing general maintenance and repairs, but no experience with a replacment or rebuild. Post up some more examples of what you've done or witnessed.

I've considered that as I have access to GM Employee pricing that extends to engines. I haven't pursued the cost and frankly I was more concerned with "marinizing" the ZZ line-up.

The only real issue with marinizing the zz series of engines would be the water pump as these engines already have brass freeze plugs from factory and possibly the inake as they do not have water inserts in manifold