New 850/SE/FE thread from Mod50 thread

[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.

[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?

[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