Prop selection for 789cc

[DylanS]

Before I realized it wasn't worth the money (because of the port timing issues with the 760 cylinders), I had bored a 760 up to a 789 (85.5mm Pistons with stock stroke) and did the basic stuff to it such as porting, lightened flywheel, upped the compression to 195, pro-x Pistons, swapped over to 62t electronics and stator, advanced the timing, all that good stuff. I also am going to be running a factory b MOD pipe to accomodate the porting work.
I was hoping to push the upper limits of the engine in order to build a nasty free style motor for cheap, and now realize that this motor doesn't hit nearly as hard as it should on the low end due to port timing issues. Im hoping to combat this with the right prop and pump set up.

Anyone have any suggestions on prop size and pitch?? I was thinking something along the lines of a solas concord 13/17 or maybe a 12/15.
Thanks.

 

[jonolove]

What prop nozzle bore pump are you currently running?

 

[DylanS]

What prop nozzle bore pump are you currently running?

In the set up I had first I had an all stock 144mm pump, I forgot the prop size because it's been way too long but it seems a bit too large as I recall it being ran in a friends 927, and the nozzle is OEM as well.
I was going to pick up a 144mm 12 vein solas pump though for sure.

 

[jonolove]

When your pump loads does it feel like the prop spins/ slips or loads up to much? Without knowing what prop you are running I'd suggest a lower pitch than what you were thinking like a 7/14 or maybe 9/15 big hub

 

[pigpen]

I'm running a 9/15 hooker on my very similar setup. Great bottom end. Depending on your elevation you my be able to step up to a 10/16 hooker. Either one would be a great choice.


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[DylanS]

I'm running a 9/15 hooker on my very similar setup. Great bottom end. Depending on your elevation you my be able to step up to a 10/16 hooker. Either one would be a great choice.


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You think that would be a good size with a 144 12 vein mag pump? Should I go with a stubby cone? I need to correct the bad port timing with the 760 cylinders.

 

[DylanS]

When your pump loads does it feel like the prop spins/ slips or loads up to much? Without knowing what prop you are running I'd suggest a lower pitch than what you were thinking like a 7/14 or maybe 9/15 big hub

I just think it cant push enough water, the pitch gives me more mid end power than I want, so I need a prop to work with the port timing to get me good low end power.

 

[jonolove]

I just think it cant push enough water, the pitch gives me more mid end power than I want, so I need a prop to work with the port timing to get me good low end power.

Bore your nozzle if you think it's loading up to much in your pump reverse jetting will help it be more snappy if it is stock 760 port timing those cylinders can still hit very hard if jetted correctly