New 850/SE/FE thread from Mod50 thread

[formeone]

Since so many complained and thought this 850 stuff was not related to the Mod50/inflatable stuff, its now spun off to this new thread of its own



mine a 49.7 cube,, we run in 850 class here or the square block 65hp from the early 70"s most everyone else race the kidney shaped70-75hp style blocks same inside almost heheheh

[850cc racer]

so yours is the block with the square exhaust cover? like about 6inches wide.. not like all the other 49ers... i have one of those blocks!!

[Powerabout]

just curious
Will the MOD 50 side plates fit on the old 3 cyl block?

[Tim Kurcz]

For Powerabout & others,

The Mod-50 uses the same crankshaft and ignition system as the 49.7 fishing motor. The early looper you talk about with narrow rectangular exhaust has no boost port - only transfers. The later engines are more potent because of the added boost port and improved internal features.

The early Mod-50's used 3-port exhaust like the 1970's fishing engines with cast in sleeves, but were later upgraded to 2-port exhaust pressed in sleeves, both using the die-cast fishing block. All had 2 boosts, 2 fingers, and one boost intake ports.

The "kidney" shaped Mod-50 exhaust cover fits all fishing blocks (with some machine work) except for the early rectangular cover engines and makes a BIG difference in power. The "pulse" tuning effect often referred to comes from this development.

Basically there are many differences in engines and specs to answer your question - after all it was a MOD class!

Tim

BTW: What elevation to you run?

[Powerabout]

Many thanks Tim
Happy New Year

So the later 2 port sleeve went into the fishing block without any block behind the bridge then?
Am I reading that correctly?
So you can fit a late MOD 50 sleeve into a fishing motor?

Cheers
Powerabout

[Fast Fred]

1.540 on a stock 49.7 75hp block goin by this APBA spec sheet, intake ports are in a high state of tune. Mod 50 from the top of the deck to the top of the exhaust port, 1.300:cool:

[Fast Fred]

So the later 2 port sleeve went into the fishing block without any block behind the bridge then?
Am I reading that correctly?
So you can fit a late MOD 50 sleeve into a fishing motor?



no chance, no way.:eek:, yes block behind the bridge:cool:

[Powerabout]

Thanks Fred
I figured as much

So we have....

1.540 on a stock 49.7 75hp - Short rod
1.393 on a SST 60 - in between rod
1.300 on a Mod 50 - long rod
1.???? on a M31 - long rod

Cheers

[formeone]

cool thanks guys for your imput,,, ,, where the intake height different as well or???

[Fast Fred]

<a href="http://tinypic.com" target="_blank"><img src="http://i48.tinypic.com/xcr67t.jpg" border="0" alt="Image and video hosting by TinyPic"></a>:cool:

[Tim Kurcz]

Actaually, the Mod-50 sleeve CAN be installed in the fishing block by boring, welding in port bridge supports, then re-boring before sleeve installation. This is an expensive mod, so I've never actually done it....... The biggest reason is to get more support for the piston skirts on the intake side - the Mod-50 uses ducted boost and transfers instead of the open channels in fishing blocks.

BTW: Just out of the shop where I built four Mod-50 ported 49.9 FE/850's, two 56.6 SLT's and a Merc 444. Three more 49.9's to go.......

[Powerabout]

just curious

Although Merc did have one bridgeport V6 the current hot ones are not
All the OMC hot motors seem to have bridgeport exhausts Mod 50 to F1 V8
can anyone explain this?

Tim
Did you use bridgeport 56'ers or oval port?

[Fast Fred]

bridge port gets a bigger port over all, oval port has a wider power band.:cool:

[Tim Kurcz]

To bridge or not to bridge........

Fred is right about the port sizes available as there are limits to unsupported ring circumference (before drop). Newer engines use oval ports because of cooling problems with bridge ports. When hot, they often expand into the bore causing a piston scuff. Eliminate the bridge, eliminate the scuff.

BTW: I've ported one 56 each - one owner preferred the bridge, one did not.

[Fast Fred]

so Tim, how much to put one new bridge port sleeve in? hows it look when done?:cool:

[formeone]

hope these pics come out for you and others,,, all this front induction reminds me of the days everyone doing it years ago ,,, we called them mumps,,,,back then,,,

[formeone]

this a prototype that i will be testing shortly,,,see if really that much better this all done on a 65hp/49er block,,, the style i run and prefer,,,

[formeone]

also will be testing new style ignition,, as soon as engineer gets it bench tested,,, it a stock omc ignition but dont need the heavy ..ie 11lbs flywheel anymore,,, will be able to just run the hub for fireing it,, and then a lite flex plate with ring gear,, as i like to run a starter,,,

[formeone]

hope ya like,,, this is front half ready to gooooo.. shall find out if it works,,,

[Powerabout]

Very nice

Hows the crankcase volume
smaller, same, or bigger?
Cheers

[formeone]

mmm depends if youwant to add the area of the newreeds???.. opening a hair bigger into block,,, and still on the side,,, as i figg omc engineers werent to far off,,, and many other outboard manufact, copied the 3holer from omc.... it a straight in shot,,, it actually not much bigger than orig for area,,,,, this all done by hand in my apt,,, with grinders and cut off tool... so much for my damage deposit ,,,hehehe

[Mark75H]

Looks good Cheney

[Tim Kurcz]

Hey Cheney,

Been turning many chips building 7 more steel OMC/45SS towers..... Looks like nice work on that front end - Yamaha if I'm not mistaken. Close call at the division meeting; glad to know we're good for another year or two. Still thick ice here (8F this morning). Be sure to let us know how it works!

Tim

[Mark75H]

The spin off thread

[Powerabout]

When the M31 had injection, whose efi box did OMC use?