Marinette Boat Forum

As mentioned in a prior post...
Post ignition tune up engines no longer stalled once trannies are engaged.
Had a great afternoon on the river!!!
Once I knew the trannies / ignition were functioning I started to increase RPMs.
All good until 2900 rpm. After approx 2800 ( 20 mph according to iPhone gps speed app) engines would bog and not produce more forward thrust/power.
I think the spare props are 17 x 19 .... But I will have to verify.
Like a dummy I did not check the current props before splashing.
Our seems to be a little odd in the cid / trans ratio dept. and I am not sure what prop would have been stock.
I would prefer fuel efficiency over power / speed.
Any thoughts?

Or if anyone has any thoughts as to what this prop ratio will produce rpm / power / speed / efficiency wise.
I see that 16 x 16 should have been stock.

I don't know if you did this already, but I would check the timing on the motors and make sure the choke plate is fully open and the 4 barrels are opening up properly. On a different boat I have, mine would bog down when I reached the 4 barrels, they were actually opening up, but I wasn't getting any fuel out of the jets. I filled the carb vents with sea foam and let it sit for a few days and the problem was gone. I also dump sea foam in the vents during lay up to hopefully keep them from gunking up over winter.

I hope those aren't 19 pitch props on there!

Jeff

My 32 footer with the same motors has 17 x 15s and the motors only hit 3,900 rpms WOT (which is fine by me--the boat leaps out of the water).

Jeff

So, given the specs on our , what would the consensus be for fuel economy but with enough to power to handle the Ohio River currents....if that ratio exists.
I still need to get to her and confirm spare prop size as well as check that all four barrels are putting fuel into the system.

16x15 was stock per Marinette site.

17x19 is pretty steep. Too much bite lots of strain on engines.

Should be a nice grove having them
Pitched to 14 or 15 like Jeff s were.

Dave

Ben, my 84 Model with 318hp was running best with 14x9 DynaQuad 3 blade cupped. I tried 14x10 also.

Correction, 318ci Twins and at WOT 4000 to 4200 RPM. Ran it hard for 10 years with no problems except moisture in Distributor caps and changing impellers every year.

14 inch wheels are used on 1:1 transmissions

16 inch wheels are used on 1.5: 1 transmissions

I do not believe he mentioned which gear he had?

dave