Re: 1970 85 hp johnson
If the engine is new to you, I'd take a compression reading first. It's good to baseline your compression so you can keep track of it over your years of ownership. It also is good to know if it is good enough to start/run that engine. I'd be looking for compression in the 110-120 range on all 4 cyls. Get some new gas with proper marine oil mixed in the tank. Check the gear oil in the lower unit for water intrusion-you may just want to change it before your first outing. If the engine is new to you and has not been run, you may want to replace the water pump impeller atop the gearcase. You don't want to have a cooling issue when it starts up. When you first get it running, borrow a laser temp gun. Check the temperature of the powerhead as it idles on the garden hose or in the water. You want to see if the thermostat (vernatherm) opens and regulates the water temp in the block. 160 degrees at each head is too hot. That engine does not have a more modern overboard telltale. You want to see some light water misting out of the exhaust relief ports at the top of the midsection when the thermostat opens (after 30-60 seconds on a cold start.)
