Mercury Mark 40-H

[Mark75H]

With so much at once, will it be possible to know if any particular mod is not helpful or negative?

[MTECHMARINE]

Looks like a bit of work on the pistons too. I see a lot of interesting holes.

Shorter intake path and finger ports??!

Wow, this things gonna be a real screamer I bet. Will be interesting to see the outcome.

[Aeroliner]

Hi Sam,
A number of the things on the engine are tried and true. Thought if we were going to build it we would go all the way. Maybe a bad decission! If it runs like crazy well take orders and if its a dud well back to the drawing board. Its going to be intresting to see how it runs when we test with Tim's 444. My bigest worry is weather we get good crankcase pressure. Carbs might also be a factor we will have play with to get it right. For starters we will use a Merc mag but we can go to a CD setup if the fire goes out.

Alan

[John (Taylor) Gabrowski]

Piston finger ports or in cases little ones called puff ports in piston skirts, their configurations, sizes and inlet angles in addition to the intake port tunnels are subjects with so many meanings and undertandings they all come to be grand experiments in the end. Some will work and some better than others. I know they were used succesfully in Anzanis and Harrisons too but they are loop engines not deflectors.

I note that your not showing the exhaust port side underneath that exhaust filler block you have machining in the picture, for now that makes me speculate your carrying out another experiment too which it is all about in the end anyway. The one big thing about deflector-crossflow engines is to produce the greatest power at the lowest rpm possible before the scavenging system which stratifies air/fuel better than a loop engine does at lower rpms than higher where loop engines go (and loop engines become more efficient still as rpms go up) inefficient and the power curve drops off. At some point all this might only be tweeking the powerband which also gets rather interesting.

[Aeroliner]

Being that there is a little intrest I can only say that the port design came from Harry Brinkmans notes and was his last thoughts on what the exhaust. We have photos of what we did that will be posted later on after testing is underway. I might look at also doing Harry's 75-H mod and make a TX660DK six pack. Some of the work is already done but if the 444 goes well the six might be the next step. Looks like that would be a legal 850 engine.

Alan

[Mark75H]

Originally Posted by Aeroliner

Being that there is a little intrest I can only say that the port design came from Harry Brinkmans notes and was his last thoughts on what the exhaust. We have photos of what we did that will be posted later on after testing is underway. I might look at also doing Harry's 75-H mod and make a TX660DK six pack. Some of the work is already done but if the 444 goes well the six might be the next step. Looks like that would be a legal 850 engine.

Alan

No, 6's are limited to "3 conventionally mounted carbs" in 850. You have to read the rules. The 44 is the only motor that is reasonably unrestricted in what can be done to it.

A 6 carb 6 is legal in 1100cc alky runabout

[John (Taylor) Gabrowski]

Out there, there are the Modifieds as classically known and now when it comes to what we are doing in essence are the extreme end being a somewhat Unlimted Modifieds or Super Modifieds because at the core is still the base stock block and internals to begin with. The target in a global sense is to shadow compete with the OMC 49 cubic inch loop engies modifiting older deflector technology taking it where it was dumped for Flatheads wholesale in Alky classes as a dead technology for racing without coming to an actual conclusion about it. The Formula E and 850 Modified classes are now the catchall for these efforts allowing for flexability for what you want to accomlish. Most everything is still available at reasonable to ridiculously low salvagable costs to what you can accomplish at different stages in economies of scale using OMC and Merc bas products in doing it all. In this too you can still get a lighter engine out of the deal making everything one whole lot easier on everyone and on gasoline which is still the only real reasonably priced fuel availble baring ethanol and methanol industries take off bumping off petroleum universally as base fuels some day??

This makes for interesting times to try and prove things out, then some might be able to sell some of it to others soon enough to expand its base of following.

[Mark75H]

Huh?? I'm getting dumber all the time. Just can't understand the post.

[John (Taylor) Gabrowski]

You just need your good cup or two of good esspresso coffee then it will all fall into place.

[Aeroliner]

Hi Sam,
Checked the 2009 rules and found this before I did the post. Maybe I didn't read it correctly. Thought it became legal for this year.

850 cc MODIFIED CLASS
POWERHEADS
1. Only service outboard motor block and crankcases which meet all the following criteria are
permitted.
a) Of which at least 1000 or more units were produced and offered for sale to the general public
as service motors mounted on a service lower unit. Approved models before 1995 are
grandfathered, and are permitted for competition in the 850 cc Modified class
b) Both foreign and domestic service motors are permitted and they shall both meet the MORC
definition of a service motor.
c) Motors are limited to a minimum of 40 cu. in. and maximum of 49.9 cu. in. piston
displacement, calculated as a function of the bore and stroke specified by the manufacturer
for that specific service motor in standard bore configuration. Please note the following
exceptions to this rule. Mercury Mark 75 (6 cyl. 60 cu. in.) Mercury 650 XS (service
powerhead) and Mercury 650 (4 cyl. 62 cu. in.) Service powerhead shall be permitted.
d) All motors manufactured before 1992 that meet the above criteria are automatically permitted
to run, however, the MORC is given the authority to disapprove a specific model engine or
specific part which violates the spirit of the service motor rule. Such disapproval shall be
published as soon as possible and subjected to a driver referendum on the national ballot
that follows.

"No additional reed ports or carburetors are permitted on a motor from the number specified by the
manufacturer. No other/additional means shall be used to introduce an air/fuel mixture into the
engine crankcase area from outside the motor. On the OMC 49.7 cu in block, any OMC one
barrel carburetor with a venturi of 1.250 (+/- 0.15) and a bore of 1.500 (+/- 0.015) may be used.
(2008 Ballot) On the 44.9 cu. in. OMC where any OMC outboard motor carburetor is permitted.
No size or measurement specs apply to reeds or carburetors, however material may not be added
to increase the size of the carburetor throat and reed ports. This specific rule does not apply to the
Mercury 4 cyl/44 cu. in. and 6 cyl./60 cu. in. motors."

Alan