Start saving for your ear plugs people...! hopefully attached 2 pictures of our next project, which is a Merc MK40 H from 1953, amazingly the engine was found by having a chance conversation with a man restoring a WW2 tank and turned out to be stored 5 miles from home. At some point the engine had been lengthened by welding in a section to the leg and a recoil stater and non standard paint job added. My thanks to everyone who has helped in the many different ways, encouraging and assisting me to get this engine and it's parts to where we are now (you know who you are guys...many many thanks) The leg has been shortened back to H height, stripping the transfer port covers revealed matched transfer port covers and the exhaust ports have been squared off and sharpened up so its had an interesting life. It feels good and not 'gravely' when turned over, but only a complete strip down will reaveal all...fingers crossed.

As it was already modified we decided even though it has the quickie bottom end with the above water exhaust it seemed a shame not to let all the noise out, so by advertising in the USA we found a set of period genuine Quincy megaphone stacks to let the engine really give voice...plus a flywheel that is really only there to support the starter sheave...this engine should sound GREAT.

The plan is to rebuild the engine over next winter then having defended the collective CMBA ears build a suitable boat, which looks like being a 'D' mod hydro, this rig should then prove to be a suitable laxative as one gets older and takes an interest in the SAGA magazine adverts.

Looking very much like a 'proper' racing motor now. Look forward to being deafened...

Now that is what is called a early Mercury 40H alky-mod racing engine! Looks right and proper! Now put some distance between yourself and your neighbours to get it dialed in. If you don't have a Mercury class D testwheel make sure you back the engine into the water locked down to yoru trailer so at least 3/4s of the prop is buried and set the carbs high speed jets and ignition (about .300 BTDC using regular unleaded gas) on the trailer. Nice work and nice result!

Quick update on the Mk 40H, slow progress, but have got extra strengthening into the leg at the join by plug welding stips to the inside of the leg to tie it all together, will look to pull it apart this Spring and see whats what inside the power head.

I HAve 10No two stroke motor cycles from the 80's period all with different types and styles of expansion chamber's,all have the silencing blanked off by sleeved baffles, BUT THIS JUST TAKES THE BISCUIT AND I WANT IT IN MY WORKSHOP!!!!
WELL DONE
Grant

Cheers, just keep the window open a crack you'll hear fire up .I'll post an update from time to time.

Spent the winter lowering the transom on Colliwobble to Hydro height around 13'' and have now finally have got around to getting the engine rebuild under way, I'm taking photos as I go so I'll upload some of them so you can see what we find... it's a voyage of discovery, this engine dates back to 1953..no Merc dealers in the UK then! So it must have come across specifically for a hydro racer. Someone has previously spent a lot of time taming the engine and extended the leg to 16'' shaft... see the pics.
The mid section has been reinforced inside and out, these legs are very thin and crack as this one had, so it's now tied together top to bottom inside by straps. All now faired up ready for paint.

LOVE IT!!!

Gear box came apart a treat...took a while as I had to make a 'fangle' tool to undo the conical end nut on the prop shaft and it's left handed! Looks like all it will need is new seals and a water pump impellor and maybe a pump body. Took a while to work out how to get the water pump housing out (it's on the prop shaft behind the prop) the extractor threaded holes were filled with body filler and hiding. Cleaned it all up to find extractor threads stripped but gentle taps to the body with the prop shaft in the vice and the whole assy inc the bearing were eased out.

I'm working thro the whole engine to make up a parts list, then I'll come back to resto and rebuild each main assy.

Pics of the drive shaft, now shortened back to hydro length, the weld is the one it aquired when it was extended, I removed the bottom slotted drive end, cut the shaft and replaced the end and re pinned it...seems to run true but will have to double check on V blocks and dial guage before assy.

Prop... If you look at the as found pics the prop is painted white but it's actually been made larger with some sort of glass reinforced resin...done nicely but when I investigaed a 'split' ...inside was the stainless prop ! It looks better in the photo than in real life but will make a starting point, 6 1/2 inch dia by loadsa pitch. It has the initials 'DH' hand engraved on the hub...Anyone know of a D.H ? a racer in the 50's/60's.