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C vs D jets

bill_w

bill_w

Advanced Contributor
Can someone tell me what the difference is between jets with a D or C after their size? I've got one each of them in front of me, and I can't tell the difference.
 
bill_w said:
Can someone tell me what the difference is between jets with a D or C after their size? I've got one each of them in front of me, and I can't tell the difference.
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You need to look awfully close, using a magnifying glass. Some differences pertain to the outer portion... other pertain to the way it's designed internally. OMC at one time put out a bulletin stating that one should not drill the jets (Yeah, I know, we do it anyway) as that changes the internal flow area.
 
so can you use a C jet if a D is specified?
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NO!! C jets are 98% used on crossflow engine and D is for mainly loopers. It is the way jets are drilled as a C feeds from center of bowl to high speed orfice where a D flows from outside bowl toward center. You should never drill a jet as the swirls left in brass can effect fuel flow and actually cause it to run leaner. A jet if need to be modified should be reamed to size.
 
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I was just wondering if the C would work in place of a D, and I could save a few bucks. Rejetting a V8 isn't cheap.
 
Are you insinuating that owning a boat might be an expensive hobby Bill? :)

Seriously, I can understand the interchange thought.
 
Joe, it seems to me that owning a boat or three can get to be a bit on the expensive side. Specially when you have to correct the last owners mistakes. :)
 
Joe, I tried your timing technique on 2 of my engines, and got identical results. 1994 200 V6, and an 88 275 V8. Had the quick start unhooked, and they both showed 28* timing when cranking. Running at 5500 they showed the correct 18*. But on my 92 200 V6 it worked perfect, 14* cranking, and 18* at 5500.
 
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