Omc triple black top carburettors JET SIZES ?

[phillnjack]

I am trying to find out what the actual sizes are of omc jets, as in drill sizes etc.
Some have said the size did not relate exactly to a drill size ???? confusing :confused:

Motor is 56 ci OVAL PORT 70hp .

I need to know what Drill sizes the jets are, and what do the letters D stand for ?

52D...53D....55D ....and 60D


In the diagram it shows (what I believe ) the main jet as a 52D and the top small jet (I presumed air !!!) as 60D.this was from 1995 onwards.
in the same carburettor in 1993/4 it was 53D at the bottom and 55D at the top. (larger bottom and much smaller top jet ) ?
can someone please explain what difference this would make and why such a big variance in the 1995 for the top jet.
must be a difference to make such a dramatic size change, but I am wondering why this happened, is it to rich it or to lean it out more ?

These are the LARGE 70hp Black plastic top carbs that only have the 2 jets, .

any info on this would be good.


http://i983.photobucket.com/albums/ae314/phillnjack3/70HP%20CARB.jpg[/URL]


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[EMDSAPMGR]

The alpha letter designated the thread size on the jet. All D size jets have the same theads per inch. Nothing to do with the orfice size. Be careful when you want to know the drill size. Hand drilled jets do not flow as much fuel as the same size jets that are drilled at the factory. Most all the older factory service manuals for carb engines have a specific master page that shows all OMC factory jets-sizes.

[powerabout]

D also means the direction they are flowed

[faztbullet]

Jets stamped with "C" are for crossflow carbs as jet flows from rear to front and loopers use "D" as they flow from front to rear.(V motors) Has to due with taper not threads as all high speeds are 1/4-20. Use a reamer if trying to open em up. Stahlwille jet reamer set is the best....

[BenKeith]

Has anyone ever told you not to drill jets. They are reamed and with a tapper. A drilled jet will not flow the same as factory or reamed jet with the same size hole.