Carburetor findings

OK the whole carburetor is back together, with the needle of the needle valve mixture control all screwed in as mentioned above.

And also noticed that one of the jet’s is not the right size, but that might be OK. The “name plate” on the outside of the carburetor shows jet sizes.Β The “Main Metering Jet” is correct : #48. The other jet size on the plate says : AB #50 but the installed one is #53. No idea what AB stands for but I assume its the jet for the fuel pump. The bigger the number the smaller the hole, for some reason.

So this fuel pump jet is smaller than what it should be, but I have seen squirt of fuel, so that’s likely OK and I don’t think it will affect the fuel flow into the main fuel injector.

OK all ready to put it back on the engine. Probably tomorrow πŸ™‚



I also made a sketch of all the tubes and valves and things inside the carburetor. As soon as I have converted that into a nice drawing, I will post that just below here.. Its nice to see how it really works. Easier to think about the issues.



Today I had a good look at the carburetor here with Warren at work.

You know how it is when you look at something that you have been looking at a long time. A pair of fresh eye’s do sometimes work. We (well Warren) noticed that the “needle” of the “needle valve mixture control” was unscrewed for about 4 or 5 mm.

But I never thought that could be an issue as in this position the valve is closed when the control lever is in the full lean position. But talking about it I think that I might have unscrewed it and cleaned it when I was taking everything apart, but possibly not screwed it all the way back in again (did this half a year ago so that memory is GONE).

Anyway, we screwed it all the way in again. From memory as I mentioned that would have been 4 or 5 mm, so quite a bit. So maybe, hopefully this is all it is. Maybe this needle valve isn’t suppose to close completely. Thinking about it now, writing this, this could be right, you don’t want to be able to close it completely, as it will kill (stop) the engine when the throttle is open. The engine runs in idle happily when the throttle is closed using the fuel from the idle “channel”, even when the mixture control is closed, but you don’t want the engine to stop.

Anyway tonight I have cut myself a nice new gasket for the carburetor. I will put it all back together tomorrow and hopefully start the engine soon again. Being the middle of winter here, I might not be able to do it until Saturday, not enough daylight left when I come home from work.

Another option I have is the “main metering jet”. I can take it out completely to give me more fuel to go through the “main discharge nozzle” into the air stream. That would make it far to rich, but an idea, just to try out.

I should make a drawing about this carburetor with all the channels controls and things. Very complex but good to have, and something to fall back to when there are problems. Now its all fresh in my head I should do that πŸ™‚

Started “her” again

Early this morning started getting the engine ready again for a test run, while watching quarter final soccer game between The Netherlands and Costa Rica.
By the time the first 90 minutes of the game had finished with a score of 0 – 0, I had finished putting cylinder #2 back, and put the back of the engine back on again.

For the 30 minutes extra time I had to stay inside and watch. No one scored, so it finished with penalties shots. In the end “we” won 4 – 3 !!!!!

OK back to the engine, Nice even compression now on all 5 cylinders, and no bad clicking sounds.

And at 4 we started “her” again.

Starts good, with a beautiful sound!!!!

But still that problem with the carburetor, not getting enough fuel into the engine. So that’s the last little problem to solve. I keep on saying last little thing here, last little thing there. A bit scary because you never know.


If I read this back in a year or so I might think: lots more problems came up and have solved, but you just don’t know….

Didn’t think it would be solved because I didn’t see anything that would cause this.Β Taking the carburetor into town tomorrow and talk with people about my problem.

So I have the feeling from now on that engine stays in the shed, nicely wrapped up in a sheet to protect it from, who knows what….

Planning to have a engine starting party with BBQ coming Sunday to celebrate this milestone πŸ™‚

Clicking noise

This morning I removed the back of the engine to search were the little clicking noise comes from that I sometimes hear.




But couldn’t find any problems here. All rollers move nicely, no trace of any of the wheels rubbing against the housing of the rollers.

The back that I took of looks fine as well.

So started spinning the propeller of, just in case its the crank shaft, master conrods or any of the other 4 conrods.

And yes the sound comes from cylinder #2 !

So next; taking cylinder #2 off.


With a bit of cloth below the conrod of cylinder #2, I can spin the prop around and check the sounds coming from the inside.

I notice that there is about 0.5 – 1 mm movement of the master conrod, sliding left – right over the crank pin of the crank shaft. After squirting more oil to the left and right of the master conrod, where that little bit of movement was, the noise there is reduced.

When the engine is running, oil is pumped in between the crank pin and the master conrod. SO this shouldn’t be a problem when the engine is running.

First thing tomorrow, I will put cylinder #2 back on, and see what happens…

Also the back will go on and them I will make the engine ready for another run !!!!!!

All valves are GO

Lapped the exhaust valve of cylinder #5 tonight again. This was the one that Rob from Auto Restorations also lapped, and still leaked a bit. But yes now its not leaking anymore. Also quickly checked the mixture valve of this cylinder.

So YES all 10 valves are sealing nicely now.

In the next few days the engine will go on the trailer again, where I will probably take the back of the engine off, to check the valve roller / lifters. Somehow they sometimes make a clicking noise πŸ™

More tests

This is whats been happening yesterday and today: Apart from family things, I started testing all 10 valves using the candle flame test. Moved the piston in the TDC position and pump it up to about 5 bar and hold the candle flame under the exhaust and the mixture inlet. Here are the results:

Candle flame leak test
CylinderExhaust valveMixture valve
#3OKLeaksFixed mixture valve.
#4LeaksLeaksFixed both.


So a bit disappointing but ah well, just needs more lapping I suppose, and hopefully that’s it and no machining.

So I started with cylinder #3, and yes lapping that mixture valve fixed it πŸ™‚ no problem !!!!

Then today I started with cylinder #4 and hoped to finish #4 and #5. Lapping both valves in #4, took two lap sessions πŸ™ This means cylinder off, lap valve, cylinder on : A lot of work……..

But anyway after a lot of work for this one, my candle flame test gave me a good result.Β No more time left for #5, so hopefully that one can be done tomorrow πŸ™‚ And then all valves are done !!!!!!!!!!!

Finished cutting the exhaust valve seat

Got a call today from Rob at Auto Restorations. He finished cutting the exhaust valve seat!

Picked it up at lunch time and spoke with him about my piston rings. He explained me how they work:

When the mixture is ignited, the rings are pushed down in its grooves in the piston, and then get pushed outside against the bore of the cylinder, sealing it.
Possibly just filling up with compressed air might not seal it, which is what I see.

So he convinced me to try and run the engine with the current rings.

And then I suddenly realized that there is a vent coming from the crankcase. So all I need to do is check how much (exhaust) gas is coming out while the engine is running. If I connect a hose and put it in a bucket of water I can see how much the rings are leaking!!! πŸ™‚

Oh yes Rob also lapped the valve, and reamed the valve guide as it was a bit pushed in halfway as it was pressed into the cylinder.

From Wikipedia: A reamer is a type of rotary cutting tool used in metalworking. Precision reamers are designed to enlarge the size of a previously formed hole by a small amount but with a high degree of accuracy to leave smooth sides.

So all good.

So tomorrow I will put this cylinder back on the engine and do my candle flame leak test for the 10 valves.

Are the rings leaking

Put the fourth cylinder on today and decided to start doing a leak down test on the 4 cylinders I have installed so far. A lot of escaping air, but none through the valves I think.

I will confirm that in the weekend after I have taken of the mixture inlets, so I can check those a bit better as well. Basically going to pump up the cylinders again and use a candle flame to see if any air comes out of the exhaust or mixture inlet.

The leak down test was disappointing. All four cylinders leaked down from 5 to 1 bar in about 5 seconds, same result as the worst cylinder last time.
With the one cylinder still off, I can definitely hear air coming past the piston rings.Β If the candle flame test in the weekend confirms that the valves are good now, then I am going to replace all the rings πŸ™

When will it ever stop!!!!!!

Valve seat machining company

Just been to an “Auto Restoration” place. They do the valve seat machining all the time. He showed me the tools they use. Just what I thought they would look like. Some creation that looks like a valve and sticks through the valve guide, and then the pull from the stem end, and twist it around till the whole seat is cut away and flush with the valve head again.

Talking with the guy, it looks like its quite normal for old valve guides to have a hole in it that is not central. So yes this is why the new one, where the hole is nicely central is creating this problem.

Yes the machining of the valve seat will be done this week, so I can put the last cylinder on for another test run this coming weekend. Still need to find out why the carburetor didn’t get enough fuel in the engine….