Sea18Horse
Chief Petty Officer
- Joined
- Jun 1, 2008
- Messages
- 626
Next on the list is some pretty extensive engine work. I was adjusting the valves a couple of weeks ago because the PCV valve has always rattled @ idle really loud. I suspected it was because of where they hooked the PCV valve to but I wanted to make sure it wasn't because of tight intake valves. They had the PCV valve plumbed into the fitting on the #8 intake runner because that was the only one the engine had. No vacuum ports on the carb at all. I've since drilled and tapped a port on the rear of the carb base where the vacuum brake booster fitting would ordinarily go. This solved the rattling problem and also gave me a centralized port to hook up a vacuum gauge.
But anyway in the course of adjusting the valves I discovered a few problems. One is a compression leak into the valley on cyl. #3. With the valve covers off I could hear what sounded like a compression leak (Sounds like an exhaust leak but with a sharper attack if that makes sense). If I'd kill cyl. #3 it would go away. A stethoscope confirmed it was coming from the valley. Bummer!
Next I discovered that it has a flat cam lobe on both cylinders #4 and #5. Bigger bummer!
It's funny that without the normal cues that one has from 40+ years of automotive repair an engine can fool you. #1, with the engine more or less solidly mounted there's not so much as a quiver. Smooth as can be. Feel for a dead miss at the exhaust? Nope, can't reach it. Infra-red exhaust analyzer? Nope, too much water. This engine has always sounded pleasingly rumpety- rumpety at idle. Well it turns out that's because it's idling on 5 cylinders :facepalm: .
All this together leads me to the conclusion that this engine was just pulled out of a mid 70s Chevy truck and plunked in here. I've replaced a ton of flat cams back in the day. It was common back in the 70s and 80s. I don't think it will be too difficult do do the work in the boat. The head gasket work will be easy peasy. Just heavy. The camshaft will likely be a whole different story.
When I unbolt the prop shaft flange I'll have about an inch of clearance there. Looking at the diagrams of the velvet drive transmission input shaft it looks like that should be adequate. I'll have to construct a miniature gantry that will sit on the motor mounts to hold the back (front) of the engine up while I pull the trans and housing. If it's not enough I'll just have to lift the engine higher is all.
Cheers.......................Todd
But anyway in the course of adjusting the valves I discovered a few problems. One is a compression leak into the valley on cyl. #3. With the valve covers off I could hear what sounded like a compression leak (Sounds like an exhaust leak but with a sharper attack if that makes sense). If I'd kill cyl. #3 it would go away. A stethoscope confirmed it was coming from the valley. Bummer!
Next I discovered that it has a flat cam lobe on both cylinders #4 and #5. Bigger bummer!
It's funny that without the normal cues that one has from 40+ years of automotive repair an engine can fool you. #1, with the engine more or less solidly mounted there's not so much as a quiver. Smooth as can be. Feel for a dead miss at the exhaust? Nope, can't reach it. Infra-red exhaust analyzer? Nope, too much water. This engine has always sounded pleasingly rumpety- rumpety at idle. Well it turns out that's because it's idling on 5 cylinders :facepalm: .
All this together leads me to the conclusion that this engine was just pulled out of a mid 70s Chevy truck and plunked in here. I've replaced a ton of flat cams back in the day. It was common back in the 70s and 80s. I don't think it will be too difficult do do the work in the boat. The head gasket work will be easy peasy. Just heavy. The camshaft will likely be a whole different story.
When I unbolt the prop shaft flange I'll have about an inch of clearance there. Looking at the diagrams of the velvet drive transmission input shaft it looks like that should be adequate. I'll have to construct a miniature gantry that will sit on the motor mounts to hold the back (front) of the engine up while I pull the trans and housing. If it's not enough I'll just have to lift the engine higher is all.
Cheers.......................Todd