K&B 7.5 mods

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Raise the exhaust to 180 degrees. Close the rotor at 65. Set the head at .012. Feed it 60% nitro. The old small flywheel helps the handling of most boats. Looks like it is on a tunnel boat. Get a back cut 1450 with around 3.2 inches of cup. The engine will have to be deeper than with an X series prop, but will be much faster.
 
Pretty much what Mark mentioned,looks like the old style engine,hopefully,the piston/liner fit is good,also,you can carefully open up the transfer passages towards the rear boost port dividers with a dremel,,some crankcases I bought later on,came from the factory with the dividers already machined,,You can see if it's been machined or not
 
Agreed with Mark he's dead on. An Irwin pipe is best one (new style-bigger volume) for me, unless you spend the bucks for carbon pipe from Jeremy from Australia (can give you his contact if needed).
I might have a 1450 that mark talking about if interested.
If your not comfortable doing your own mods, I can help you with that for $75 shipped back (if in USA).
 
Agreed with Mark he's dead on. An Irwin pipe is best one (new style-bigger volume) for me, unless you spend the bucks for carbon pipe from Jeremy from Australia (can give you his contact if needed).
I might have a 1450 that mark talking about if interested.
If your not comfortable doing your own mods, I can help you with that for $75 shipped back (if in USA).
how much for the prop ? my engine is old may not worth doing mods .
 
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Yeah Rod,,if the engine is old,,depends on how much wear it has,, the piston should pinch in the liner at top dead centre with glow plug removed If the bearings are old,you'll need to replace them,might have traces of corrosion,how sloppy is the conrod to crankpin fit ?,,then you have the front bearing/housing/crankshaft seal between bearings that could wear if it's been run with worn bearings,,problem with these engines is that new piston and liners are hard to find,and maybe the large bearing,,some folks in here might have some as spares,,,or just replace the bearings and run it ,might have to run smaller props though, if it's a bit worn out
 
how much for the prop ? my engine is old may not worth doing mods .
Just got wife home from surgery stay.. I'll need to see what I have on the prop, but ($20 shipped if I do). If your just playing and not racing just run as is. The older 45's has a smaller crank ID than newer ones, so I'd agree with others not worth changing. (BUT I have new bearings to fit it either way). I'll let you know by tomorrow on the prop.
 
Rodney
I do have the 1450 prop that I've ran for yrs and works for me.
My PayPal (ff or add 3%) to. [email protected]. need your complete address. What's a good number to reach you if any issues.
Mine (812-453-8137)
 
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