Project Centaur

[Michael S.]

I think the valve still has some grooves. The valve seat looks better in the picture. Maybe sand more with a finer grinding paste.
If the grinding pattern looks good, you can install the valve and then fill the cylinder head with petroleum from one side to see if it is tight. If no petroleum flows through it is already very tight.

Michael

[redhouseluv]

I saw those grooves and did wonder if I should go further, but was being cautious not to over do it; you can't see them, but the seat has some similar grooves. That's very true about filling it up and seeing if there is a leak, that's how I tested it in the first place

[redhouseluv]

I still have my doubts about. this valve, if you look at the top edge where the slot has been made to turn the valve when grinding, it is showing when you look from above. Also take a look at the side view - not sure if it needs a new valve as it may not be deep enough to effect the seal?

I don't want the slotted edge making contact with the valve seat when I'm lapping as I think is would cause some damage?

It might just be time to put it all back together, if I get compression all good, if not ........

[Roger B]

That should be OK, there is a clear matt band around the valve. Put it together and try it but remember to recheck the valve clearances. They will have been reduced due to the re-machining of the seats.

[Jasonb]

You only need a narrow continuous band of contact all round so the slot should not matter.

Often the diameter of the valve head is larger than the widest part of the valve seating surface so the slot would not even come into play.

[Charles Lamont]

The finish on the valve and seat is a strange to me - it looks like there's still lapping compound on them, but there isn't as I have scrubbed them meticulously several times with warm soapy water to remove any trace. I guess this must be what it looks like; I had to use the 280, followed by the 400 and final 600 before it made any impact.

I guess the next stage if the above is all ok is a rebuild to see if I now have compression. As this is a IC Engine I'm going to have to put gaskets and sealant in even for the initial test unlike a steam engine?

Yes the ground surface will be a fine matt grey. I am not sure soapy water will do. I clean things in the shop with paraffin (kerosene) and a toothbrush. I find a small loaf tin makes a handy bath.

[redhouseluv]

I've had a bit of a disaster and nearly a very nasty accident....

The engine wasn't giving much more compression, but fuel was getting sucked in and leaking through the top bolts of the carb, there was a pop, then another pop and next thing the engine was on fire, so was the bench and my hand! I managed to get engine to the floor but not without the fuel tank leaking more fuel and catching things on fire on the shop floor.......my wife came to rescue and we managed to put everything out.

After what happened I've kinda gone off this engine and won't be continuing. You can see the burn marks on the wooden frame and the blackened carb. I have a feeling there are more things which are in need of correction.....for instance the bearings, right hand side, compared to LHS have been so badly machined there is a huge aluminium spacer inserted to make up the difference. I think if anything its put me off buying unknown IC engines from auctions on the cheap! 

On the positive side I have learned so much from the whole exercise and am grateful to all those who have assisted along the way. This hiccup hasn't put me off and I will attempt another IC engine in future, but one where I make everything myself from start to finish.

[Kim]

Yikes!  That sounds quite frightening!  I'm glad you and everything (except the engine) seem mostly OK. I hope your hands didn't get burned too badly?

Kim

[redhouseluv]

No I'm fine thanks Kim, my pride is a little injured, but that's repairable.......

I must admit I'm thinking how fuel was coming up through the 'lid' of the carb via the bolts and throttle - it didn't have any gasket or sealant around it when I took it apart originally and maybe it should have?

[Roger B]

That could have been nasty    glad all is ok.

Put it on a shelf and in a few years time you might be tempted to try again.

[Jasonb]

Good to hear you are OK, Was that your pants in one photo, hope they did not catch fire too

For the fuel to be coming up it sounds like the engine was flooding, maybe the valve stuck open and the tank was a bit high? If you come back to it that bearing looks wider on the outside so could possibly be turned around.

A good time to remind everyone to have a suitable fire extinguisher in the workshop and that when test running an engine you don't need a whole tank full of fuel.

[redhouseluv]

No pants on fire luckily, just the rags I tried to put the fire out with!

My wife bought me a fire extinguisher and a fire blanket for Valentines Day 

I may come back to it one day, but for now I'm moving on and going back to steam, then I'll take a look at building an IC engine from start to finish

[michaelr]

Good to hear you are OK after the mishap. It doesn't matter now that you have given up on the engine but that alloy spacer at the right hand bearing, I think you will find it is the lubricator banjo that feeds oil drip from the bearing up to the crank pin.
I stand to be corrected.

[redhouseluv]

Hi Michael

You are correct, I just looked it up (see below) - good to know if/when it comes back for another look, thanks