4 sale 55 H

[jrrennie]

Dad used to race boats in the mid to late 50's.
This motor has been sitting in garage for at least 35 years.
(as far back as i can remember)
I've never seen it run nor have i ever tried to start it.
From what i can tell, the cowls used to be white and were painted black at some point.
There is no I.D. plate on it that i can find.
S/N on block is 984255
Edit: It does have a Quickie lower unit.
I've been told by a few that race, that it's probably worth between $2000 and $3500. I'm asking $2500 OBO
email me for pics
Thanks, Dean
email biffrennie@yahoo.com
phone 253-732-0224
Seattle/Tacoma

[sam]

If it doesn't have an ID plate, how can you distinguish it from a 30H?

[jrrennie]

Sorry SAM,, I can't answer that.
I know very little about these motors and what distinguishes one from the other.
My Dad told me it was a 55H and others who have seen the pics said it was.
I did a search on the WWW and found that the serial number was in the range given for the 55H.
If anyone else cares to help out here,, that would be great.
Thanks

[sam]

A 55H should say THUNDERBOLT on the fuel pump side and have KA7A stamped on the carbs

A 30H on the other hand will say TURBO FOUR on the fuel pump side and say AJ something on the carbs

[jrrennie]

yes.. it says THUNDERBOLT on the fuel pump side of the motor and the carbs are KA7A

[goodtry]

Saw the motor on another site. It's a 55H it does have the 40H tower with the brass exhaust fitting but the newer correct style long skeg gearcase.

[RandY Aveline]

is it locked up ??

[trident]

Mk 55 H

OK, not to give anyone a hard time, just to clarify,

Yes, 30H's say Turbo Four cast in below the pump boss, as do all 30 cu. in. blocks, pleasure or racing. The OEM 30H carbs were AJ 49 or AJ51.

Yes 55H's say Thunderbolt cast in below the pump boss, as do all 40 cu. in. blocks, pleasure or racing. OEM 55H carbs were Carter N or KA7A. Early ones were Carters, later 55H-1, the white squaretops, came with KA7A's and most early ones were converted to KA7A's (Mercury offered a conversion kit, with instructions).

Here is where it gets sticky... after years of racing the 55H's, blocks were in short supply, so the Mark 55 service block (pleasure) was allowed by the SORC with the carb holes remachined to accept the larger KA's, as a legal replacement block. The service blocks had lower porting than the 55H's, were off a mph or so, but turned equal or better lap times. These motor raced on, through the end of the Mark 55 era. They were even run in the first year of the Merc Challenge, as the 44XS was not released until the following year, 1987.

So, a 40 cu in. Merc on a D Quicky may or may not be a 'real' 55H, depending.

A quick way to check for the high port H block vs. the low port service block, is to pull the intake (transfer) port cover on #2 or #3 as they're easiest to get to and to look straight in the intake ports. If the cutter making the port openings cut into the end wall off the transfer passage (left side in your view) a good 1/16" or so deep, its the high port version. If the cutter just skinned that wall lightly, leaving a faint mark, often tapering from end to end, its a service block.

So a 40 cu. in. block on a 40H tower with a long skeg gearcase could be a Mk 55H, or it might have been converted or built to be, for lack of a proper designation, what I call Mk 55S, as in 'service block race motor'. Note, my label, nothing official about it... Lots of those motors are still around, as they were the last version actually raced.

I had several MK55S motors that were basically built-ups of good service blocks, with fresh bores and new pistons, on H towers and gearcases (Still have my Merc Challenge motor and a 'real' H). Even some of the gearcases were factory replacements, as they were a bargain, once. There weren't any new motors available and most the original 55H's had been run to death or weren't for sale... so you built what was allowed and available. Kind of like the 44XS now, come to think of it.

Hope this helps.

Jerry Wienandt

[sam]

MK55S is a real Merc designation for a fishing Mk55 with an electric starter but no alternator. They came M for manual, E for full electric, and S for starter only.

[trident]

Mk 55 H

Yup, like I said, "what I call Mk 55S, as in 'service block race motor'. Note, my label, nothing official about it... "

No pleasure motors in my shop, nothing but race motors. When I'm looking to keep track of 'real' Mk 55H's in my records versus later service block equipped ones, I use the 'S' designation for 'Service block'. When I'm looking at a row of blocks on the shelves, some with covers on, I write the designation 'H' or 'S' along with bore size, etc. on that flat area on top of the block with a felt pen... saves dragging them out and opening them up to remind myself what they are.

You can call them whatever you like.

The point I was making is that many Mk 55 H's turning up for sale aren't really Mk 55 H's, in terms of being untampered with and original. Just because it's on a Quicky unit doesn't make it an H. And now, prospective buyers know how to tell...

Jerry

[sam]

Mark 55S is not "my" designation ... its the factory's

Jerry, I just didn't want some novice collector getting excited when he finds a factory Mark55S ...