For those who have experience re-powering old sterndrives I’d really appreciate your opinions.
I bought this boat used a week ago. It was advertised with a cracked starboard exhaust manifold. After examination I found two 4” block cracks as well. I offered much less than what he was asking (approximately trailer value) and took the boat home. The seller was the second owner and had taken excellent care of the boat for 30 years. Unfortunately something went wrong with the winterization 3 years ago.
The boat came with all the original paperwork, brochures, engine and outdrive operating manuals, etc. really a pretty sweet little time capsule. It’s cosmetic condition is credit to loving owners and impressive craftsmanship from the boys from Kansas. I’ve owned two modern Chaparals over the last 15 years and even this antique appears a step up in quality.
For those with experience on the old Merc’s let me know what you think. What I have is the original Mercruiser 260 with the Rochester Quadrajet and the pre-Alpha outdrive.
The block cracks are of course my biggest concern and I bought the boat figuring it was nice enough to me to warrant a reasonably priced re-power.
I temporarily sealed up the cracked manifold using permatex in order to do some engine testing. My hope to possibly stitch weld the block if there was no sign of an internal leak.
After I got the manifold sealed I checked the plugs and ran a compression test. Everything looked really good. 150 lbs across the board. I changed out the plugs for new while I was there. Then I pumped 18 gallons of old gas out of the tank and poured in 7 gallons of fresh non-ethanol with seafoam. I replaced the thermostat, attached muffs and after a little cranking the motor fired up. After some fiddling with the old Rochester i got it to start idling and eventually hit and hold operating temp (aroud 145 degrees) Oil pressure looked good. I repeated this three times, running it approximately 10 minutes each time, and every time the oil on the stick is perfectly clean. No milk. All good news. I’m looking for a welder or considering some JB weld for the remainder of the short season and a new Starboard Manifold. But one problem persists, after i reach operating temp, the exhaust gets steamy. I’m afraid that external crack might be internal as well. I might have to do a leak-down test.
If it is time for a fresh new 350, I’m curious about thr best way to proceed. For example, what years are compatible with my “pre-alpha outdrive. Since it doesn’t make sense to drop 10k on this boat, what’s the best way to approach it? Reman long block, good used pre-86 260? Good used new 5.7 w/alpha1?
If you’ve read this far, thanks. Here’s some pictures
https://imgur.com/a/XospsOe
