Mercury MK40 H modified

[grant]

It could be Dave Howell A.K.A FLOATER, I wasnt aware he was a racer from the 50's/60's though,but he only tells you what he want's to!!. come out of the closet Dave!!!
Good work and a lovely project Steve.
Grant

[Alacrity]

Great stuff, keep it coming!

[Healey75]

Bit more.... so nice to work on a fresh water engine. Just needs a good clean up, paint and re-assy.

[floater]

Cracking project. I am constantly amazed by what continues to turn up.

I have taken a copy of your first picture to keep in my wallet. When my neighbours turn up to complain that I'm running one of my motors for the N th time I will calmly show them the picture and with a smile say things could be worse

I resent the insinuation that I may be the DH in question, that motor pre dates me by a very hefty but still undisclosed margin.
I suggest that as the motor is obviously a flyer it is De Haviland

Cant wait to see it (and hear it ) finished.

[Healey75]

You can always borrow it to scare the neighbours once it's finished... I'm going to use it as a petrol powered pidgeon scarer.

[Healey75]

Bit more...powerhead on the stand ready to strip and naked, you can just see the exhaust ports which have been opened out, I'll post some close up pics if I can shortly...so far it's all looking good, crankcase is held together with 24 bolts...

[Healey75]

Pictures of the porting, major porting job done in the past, normaly the ports are more or less circular with thick webs between, both inlets and exhaust have been squared up to the max and the webs reduced and knife edged. The reed block has been faired up internally and the crankcase/carb flanges opened out and faired ro help gas flow. Transfer port covers have also been faired and matched to the ports. This all seems way past what would normally be recommended!

Poking about and looking through the ports, the pistons look to be some what pitted and maybe a bit burnt...I'll split the crankcase and pull the crank and post what I find...

Plenty of coke around so it's been well used in this spec so it should run, the carb butterfly splindles holes are also worn and need bushing as well, pointing to lots of use.

[Healey75]

Good news bad news...It's all apart and and on a quick look the crank and bearings may well be reusable, it's the pistons that pose the problem, the engine has been running with these 2 pairs of pistons, so bearing in mind that it will have very limited use (the fun police will see to that) do I put it back together as is...???

I belive pistons and rings are hard to find now as this engine is nearly 60 years old...I'll try to get some feed back &advice from the USA. In the meantime I'll clean everything up and check the clearances etc and complete a shopping list of spares required to get it all back together.


Comments please guys...

[Healey75]

Have spent many happy hours with paint stripper and a pressure washer and have found a few more things out about this engine...its had an interesting life
What appeared to be a casting fault on one cylinder is in fact a welded repair where a piston has let go and punched through the head. you can see from the pics that its been repaired both inside and outside but the bore looks ok!

Also on another cylinder where the ports have been opened out so much the water jacket has been exposed and then welded up. On this same cylinder the liner has dropped off the exhaust port divider web.

But hey ho, its been running like this as there was lots of carbon about so I've ordered new seals etc and 3 piston rings to replace those that just would not unstick from the grooves and I'll bung it all back together.

[Healey75]

All stripped ready to work on, and a trial fit of the exhaust filler blocks, these castings go over the exhaust ports and direct the exhaust straight out the side of the engine into the stacks. I need to decide if I should drill galleries in these for cooling water or just run them hot with no internal exhaust cooling as they have been previously, the cooling water will exit the block and then be sprayed on the outside of the elbows on the stack plate... before then I've got to trim and ease the filler blocks into place by removing just enough metal to positon them just below flush with the gasket face, then when everything is bolted up they can be bedded down onto some sealant or filler.