This morning's attempt to start my Alfa 33 engine in my Nova kit car failed. The fact that I spent nearly 3k on the new engine makes me very unhappy. To update you I collected the engine and fitted it last year. The car is being restored so it's been sat in my garage since then without the car seeing the road. During this time I've started the engine every now and then. It's never started straight away but I'm not too bothered by that as the carbs need tuning properly. What bothers me is something else happening...
- New engine
- Loads of fuel (fuel filter full and I can see fuel wooshing through it)
- Battery - fully charged (may as well call it new as it's only been used to start the thing on the odd occassion and has never gone flat.
On the press of the button the engine turns over seemingly fine but I notice that every time I press the throttle the turning over speed slows down. During turning over (presumably once the fuel reaches the carbs) there's the occassional sound that it has fired but it doesn't 'catch' (actually start). From experience when it fires I need to stamp my foot on the throttle to make it 'catch' but that has the adverse effect of slowing down the turning over. Another press of the button and again the turning over slows down when I press the throttle, this time almost grinding the turning over to complete halt unless I release the throttle and then it turns over OK again. All I can describe it like is like a 'compression lock'. I try again - this time it's becoming noticable that the turning over speed is slowing down with no throttle depressed, so I'm thinking uh oh, the battery is running down. Eventually I give up as the turning over speed is almost non existent.
What's worrying me is the slowing down of the turn over speed when I press the throttle, like the engine is getting a compression lock. I may have used an incorrect term here but that's the best way to describe what happens. It's like the whole engine struggles to turn over for a second and then suddenly the compression 'un-locks' and it turns over OK again. This slowing down of the turning over is what's stopping it starting. When I got the Nova back with the new engine this compression lock wasn't happening at all - it turned over fine every time and after frantic stabbing of the throttle every time it fired, it eventually started.
I fiddled around in the engine bay until I got fed up and locked the garage up. I did notice that one of the plug lead ends where it goes into the distributor seemed to be missing it's little (copper?) metal end bit. There was just what looked like a broken plastic lug within the rubber weather protector. Not the main center lead but one of the 4 others. I'm sure that isn't helping matters with the firing but of course has nothing to do with the turning over 'compression lock' issue. There was no sign of this broken metal end loose within the distrubutor plug hole.
I put the battery on charge. Three hours later...
I took the spark plugs out. All four of them were sooty matt black on the tips that wouldn't come off with a rag and cleaning fluid. I used a wire brush to clean them up.
I cranked over the engine with the spark plugs out. To my relief there was no water or fuel coming out of the holes where the plugs sit. I poked my finger in - all pretty normal. The engine turned over quickly with none of the compression lock I'm describing.
I put the plugs back in and turned the engine over. This time it wanted to fire a lot more than previously. My guess is because the previous failed attempt (2 months ago) sooted the plugs up. Maybe also the fact that I have run it on the odd occassion has contributed to sooting the plugs up. Also it could be running a bit rich as the carbs were only tuned in as much to get them working.
The 'compression lock' sound is still there though. When it happens it is always on every 3rd stroke. Hard to explain. I've uploaded some videos to youtube which demonstrate what's happening. It's not as noticable when turning over from a fresh battery but as it wears down it becomes more noticable, especially Attempt 4 video...
Attempt1 - YouTube
Attempt2 - YouTube
Attempt3 - YouTube
4th Attempt (on this vid you can hear the compression thing happening on every 3rd stroke.
Attempt4 - YouTube
Any advice or help on this would be much appreciated.