Need info on "how-to" taper-bore nozzle

standupjetski_com

standupjetski_com

Location
St. Croix River
I'm taking a composite nozzle to my brother who is a machinist to have him open it up to 84.5mm.
I've been reading that the bore also needs to be tapered.

Is the stock bore tapered?
Where is the taper supposed to start and stop?
How much is it supposed to be tapered?
Which way does it taper (stupid question).

I just want to make sure I give my bro all the specs he needs to do it right.

Would I be better off shipping it to Lehr?
 
brentR

brentR

way fast whitey
Location
Toronto
it would make sense to taper out from the impeller
measure the two diameters and length of nozzle to figure out the taper
 
#ZERO

#ZERO

Beach Bum
Location
Florida - U.S.A.
Yes the stock reduction nozzle is tapered slightly.

You have to chuck the nozzle up on a lathe and cut it using a long boring bar at about a 2 to 3 degree angle.

The angle tapers inward with the small end toward the exit and the diameter mostly dependent on the thickness of the nozzle.

If you're using the stock siphon bilge, you have to stop before the fitting unless it's removable like on Pro-Tec nozzles.
 
Speedfreak

Speedfreak

Location
So. IL
Does it really matter if it has a 2 or 3 degree taper as long as the minimum is the same size? I have bored my half a dozen or so and all of them were straight. If you are worried about that extra volume just have your brother make a stubby freestyle cone that would be better.
 
standupjetski_com

standupjetski_com

Location
St. Croix River
Speedfreak said:
Does it really matter if it has a 2 or 3 degree taper as long as the minimum is the same size? I have bored my half a dozen or so and all of them were straight. If you are worried about that extra volume just have your brother make a stubby freestyle cone that would be better.
Click to expand...
I'm currently running a wetwolf cone.
Supertune recommends tapering the bore in a few different threads I've read.
 
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