Mercury Mark 40-H - Page 3

Aeroliner · 03-23-2008

As soon as it gets warm we will break the engine in on a hydro. I will give you the speeds as we go throught the testing. I expect that we will see close to 80 mph , hopefully more, if all goes well. Doug Kay dose all my 4 cylinder work and I have to say I have found no one better. I hope to make a few D's wonder how an old mark 40-H could run like that,

Alan

**Mark75H** · 03-23-2008

Quote:

Originally Posted by Aeroliner

As soon as it gets warm we will break the engine in on a hydro. ... I expect that we will see close to 80 mph , hopefully more, if all goes well. ... I hope to make a few D's wonder how an old mark 40-H could run like that

Aeroliner · 03-24-2008

The engine is setup with KC6A cards and big read blocks to help it on the induction side. Then the interior of the block has been opened up to increase the flow to the intake ports. Both intake and exhaust ports have been reworked to allow for more flow. These are done to the Harry Brinkman specification. I have to note that the block had been ported with a file before we started the conversion. The largest changes have been making the engine into a 44 cubic inch engine using current flat top pistons. The cylinder domes were replaced from a Mercury power dome engine. The compression was also increased during this operation by installing them lower. The engines has 190 psi on a check of the compression after its first tank run. I expect this to come up a little. We are intrested in how the segmented exhaust is going to work in that the devider was left in from the standard 40H block. I beleive the engine is more capable than the current 44XS engine, but I guess we will see when we do some on water testing. The photos show some before and after shots of the build process. Have added some closeups of the ports.

Aeroliner · 04-01-2008

We have completed the 40-H and hope to test it on a hydro soon. We now have the "D" cones and bearing carriers in stock. See aeroliner-boats.com for photos and pricing. Have sold a number of them allready but we will always have them in stock. Have attached photo of the engine plus the 1959 55-H that Doug Kay has just completed.

Alan

Aeroliner · 04-01-2008

Hope you like them

**Mark75H** · 04-01-2008

Both are absolutely beautiful!

Any chance of seeing them displayed at the Antique Raceboat Regatta at Clayton, NY this summer?

I was going to ask if the 55H was a 1959 or 1962, but I can see the answer on the model serial tag

Aeroliner · 04-01-2008

We hope to show them a few times this year. We just showed three engines at the Mount Dora show which moved acrossed the lake. Attached are a 30-H, 55-H and a 58-H.
Alan

**Mark75H** · 04-01-2008

I'd really rather not see the 58H ... even though Merc applied to have it be a legal motor in NOA, they never made it.

It just becomes confusing and makes people doubt the rest of your excellent work.

Aeroliner · 04-01-2008

Even though Mercury never made a 58-H I beleive that its a legal APBA "D" engine now to run with the 44XS engines. We have a pair of these engines that my brother and I hope to run this summer if we finish the two "D" boats we have under construction.

Alan

**Mark75H** · 04-01-2008

44 cubic inch motors are legal as of last year, but that does not make them "58H's"

KG4H, KG7H, KG9H, 20H, 30H, 40H, 55H and 75H are actual Merc model names from the 1950's, not "generic" terms; for instance ... a KG9 powerhead on a Mark 40H tower and foot does not become a KG9H ... it is still a KG9 powerhead over a Mark 40H tower and foot, a Mark 15 powerhead on a KG4H tower does not become a Mark 15H either ... Merc never made it that way, even though it was legal to put the pieces together and race them that way.

Like I said, showing a "Mark 58H" decreases your clout, no matter how shiny it is