loco
Petty Officer 2nd Class
- Joined
- Apr 25, 2010
- Messages
- 154
Hi all,
Long story short, I had to re-fit my inlet manifold as I had a vacuum leak in between the inlet manifold and top of the engine block. I used new gaskets, sealed it, torqued up etc. by the book.
As part of it, I rebuilt the carb, using a lighter spring for the secondaries which are vacuum operated. All seems good now, with strong, stable vacuum.
Before this, I had one breather from the rocker cover going into the flame arrestor, and the other going into the vacuum nozzle in the 4bbl holley carb.
To maximize vacuum, I sealed the vacuum nozzle, and had both breathers going to the flame arrestor.
I'm now seeing a bit of milky oil turn up. I can see it milky in the rocker cover where you fill the oil, and a bit at the bottom of the dipstick. Engine runs amazingly and has loads of power. It's had maybe 6-7 hours of running, and the oil level is maybe a fraction high (like 2mm above upper level).
Thoughts:
- I've screwed up the inlet manifold refit, and there's cooling water going into the valley (engine is raw water cooled
). I've checked the torque on all the inlet manifold bolts and it's spot on, so I doubt this.
- I'll run a compression test to see if it might be a cylinder head gasket (pretty unlikely. Engine has maybe 250 hours on it and never overheated).
- Changing the breather setup has messed things up. I fish with the boat, which means quite a few stop-start short runs, so the engine will be sucking in moist air as it cools a lot (and runs cool anyway as it's raw water cooled). I'm thinking I should put a T-connector off the carb vacuum nozzle, then have both breathers go to it, with check valves in each. This would mean the engine is actively sucking out fumes and vapour from the engine, and the check valves should reduce the amount of moist air sucked back into the rocker covers.
Any other thoughts or ideas greatly appreciated!
Long story short, I had to re-fit my inlet manifold as I had a vacuum leak in between the inlet manifold and top of the engine block. I used new gaskets, sealed it, torqued up etc. by the book.
As part of it, I rebuilt the carb, using a lighter spring for the secondaries which are vacuum operated. All seems good now, with strong, stable vacuum.
Before this, I had one breather from the rocker cover going into the flame arrestor, and the other going into the vacuum nozzle in the 4bbl holley carb.
To maximize vacuum, I sealed the vacuum nozzle, and had both breathers going to the flame arrestor.
I'm now seeing a bit of milky oil turn up. I can see it milky in the rocker cover where you fill the oil, and a bit at the bottom of the dipstick. Engine runs amazingly and has loads of power. It's had maybe 6-7 hours of running, and the oil level is maybe a fraction high (like 2mm above upper level).
Thoughts:
- I've screwed up the inlet manifold refit, and there's cooling water going into the valley (engine is raw water cooled
). I've checked the torque on all the inlet manifold bolts and it's spot on, so I doubt this.- I'll run a compression test to see if it might be a cylinder head gasket (pretty unlikely. Engine has maybe 250 hours on it and never overheated).
- Changing the breather setup has messed things up. I fish with the boat, which means quite a few stop-start short runs, so the engine will be sucking in moist air as it cools a lot (and runs cool anyway as it's raw water cooled). I'm thinking I should put a T-connector off the carb vacuum nozzle, then have both breathers go to it, with check valves in each. This would mean the engine is actively sucking out fumes and vapour from the engine, and the check valves should reduce the amount of moist air sucked back into the rocker covers.
Any other thoughts or ideas greatly appreciated!
