Fast Fred's OMC Mod 50 secrets Thread #2

**Popa Sam** · 06-22-2009

SST60 mains .073D. air .033.
Stinger mains .056D. air .025

**Powerabout** · 06-23-2009

Popa Sam
When I look in the web parts book on 75hp
1988 back to 83 have an idle mixture screw,
1982 back to 79 have 3 fuel jets
1978 back have 2 fuel jet carbs

70's did different things and some have an idle air jet like an sst

seems to have been lots of changes...
Powerabout

**Powerabout** · 06-24-2009

Guys

Whats different about the sst 60 cyl head over a stock 70?
I notice its a 2nd effort (Seaway) only part?

Thanks
Powerabout

**Popa Sam** · 06-24-2009

Originally Posted by Powerabout

Guys

Whats different about the sst 60 cyl head over a stock 70?
I notice its a 2nd effort (Seaway) only part?

Thanks
Powerabout

About .060" to .120" depending on which model the 70 came from.

**Fast Fred** · 06-24-2009

it's countersunk, the squish band and the chamber are pushed up in. the stocker head is flat at the squish band, so on the SST head the crown of the piston goes by the head gasket and in to the head, on the stocker,the crown does not pass the deck of the case.

**Powerabout** · 06-24-2009

Fred

So the sst block has a lower deck height than a stocker?
Can yu make a sst block from from a stocker if you just get the sleves and deck it?
Is the squish band still flat with the piston surface or is it tapered from the outer edge?

Thanks

Powerabout

**Fast Fred** · 06-25-2009

you can cut the port map of the SST60 into the stock case. a solid mold case is stronger than lost foam. have yet to see a SST head, but i'm thinkin it has a flat or neutral squish band

the deck hight is a set spec for the SST, not so much on the stocker, on the stocker the piston can not clear the deck thare is no room for it to do so. the crank spec on the throughs is +/- .011 thou which is a ton.

**Barry Strawn** · 06-25-2009

http://www.opcrace.com/TECH/60.doc

**Powerabout** · 06-25-2009

Ive got a 91 70 head off at the moment.
I'll measure it tomorrow.

**sheuninck** · 06-25-2009

Originally Posted by Popa Sam

SST60 mains .073D. air .033.
Stinger mains .056D. air .025

i cant seem to get the sst60 carbs to do better then the original flappers. tried 73, 69, 65 all brown (except the odd carb... all black), 69 was fastest, but still way slower. what are the air jets all about! do i need to match them when i change the main jets??? need a carb that matches the two i have with two vents... any out there?