Fast Fred's OMC Mod 50 secrets Thread #2

[Powerabout]

850 true
its a tricky one
it has 49er head bolt pattern?

[850cc racer]

thats true true true.. you are on the ball.
it may be just the exhaust tricking us!?

[Powerabout]

Is it a reverse printed negtive of a M31?

[genea01]

cool engines do you have any updates on the boat and when is that race you going to run in

[Fast Fred]

ya that is a bridge port Mod50 block, the one before the 31m, called "the straight in", had pressed in bridge port sleeves, 31m front 1/2. can't get the pistons in need for it, could go with new sleeves but can't say i've seen any replaced sleeves that looked like all that when finished.

so got a 56, guna give it a try, gots all the parts, runnin that Mod50 bridge port map

[850cc racer]

fred what are the two modas in the pics? What pistons u need?

Im pulling my mod 50 apart tomorrow.... Few things to do.. I need to install new lead ropes to keep all those ponies in!!!

[Powerabout]

ya that is a bridge port Mod50 block, the one before the 31m, called "the straight in", had pressed in bridge port sleeves, 31m front 1/2. can't get the pistons in need for it, could go with new sleeves but can't say i've seen any replaced sleeves that looked like all that when finished.

so got a 56, guna give it a try, gots all the parts, runnin that Mod50 bridge port map

Ya gunna use the Mod 50 rods or the stock (4 inch?) 56 rods?

[Fast Fred]

Ya gunna use the Mod 50 rods or the stock (4 inch?) 56 rods?

ya was thinkin about that, i go round and round with that, I need to get to the Top O'. there are some Bad A$$ 56ers up that way, likely they gots stock rods,
not likely they gots a Straight in 56er, thinkin my 19-s powerhead be at +.040 by then,maybe not, see how she fairs.

i need a set of +.050 for the bridge port case.


in the shot you gots a New SST60, single carbs, and a stright in front 1/2 on a solid mold case.

[Powerabout]

I would interested to know what the port height difference there is between a sst60 and a MOD 50
SST 60 map is on the apba site

The SST 60 has an operating range of 7000 to 7500
do you know what the MOD 50 is?

If you can tell me how long a MOD 50 rod is I will work out the timing differnce for you over a 4inch 56 rod
but a 50 rod in a 56er will mean custom pistons
There is a company in Australia that will do one off stuff a they specialise in vintage stuff so people only order a few. I haven't asked yet but wonder if they would do some?

[Fast Fred]

the SST60 specs i got say, from the top of the cyl, to the top of the exhaust port chamfer, shortest would be 1.393. the Mod50 got way more width.

factory spec is 7400 rpms on the Mod50, on the Dyno my powerhead did not start to lose power till 8000rpms

i've heard them SST guys talk about 9000+rpms,?, i'll keep my head low