More Pitch?

[DairymanNM]

OK. Let's assume I have put a new carb, headers, mufflers and even went as far as to have a new cam built for my direct drive 455 Buick. Before all the "work", I had the pitch set half way between the 2 and 3 mark on both blades and was turning 2800 RPM. When all this new power and torque is available I am still limited to 3000 RPM per the propeller manufacturer (Sensenich). Do I put pitch in the blade past the last mark on the blades or does that cause me to lose propulsion? If you have read my last post you will understand that minus a few poor navigational decisions I feel my boat suffers from a lack of power. Especially since it will not come onto plane in deep or choppy water.

 

[a1mudpuppy]

I hate to say it but you need a reduction unit on the back of that 455. Then go with a 3 or 4 blade prop. You need the quick snap that the reduction unit will give you to get the boat up. But I would think that the 455 would get it on plan sometime!

 

[jim]

I think if you check out the web sites mentioned in the other thread, you will see that your 73 has a lot lower compression and maybe different heads than the 69 and 70. The guys on those two sites should be able to tell you how to get some HP and torque out of that engine. GM went to low compression on all their engines in 71 so that they would run on regular. That is probably why the guy with the 69 gets better performance. More pitch will reduce the RPM.
Jim

 

[Anonymous]

CRACKERS RIGHT.THEY DO HAVE A LOT LOWER COMPRSSION,BUT IT`S MAINLY DO TO THE FACT THAT IN THE BUICK 455,THEY PUT DEEPER DISH PISTONS IN IT.THE WENT FROM 5/32 TO 1/4 INCH.YOU CAN MAKE UP ALL THE DIFFRENCE WITH FLAT TOP PISTONS.AS FOR NEEDING A GEAR BOX,I RUN A 455 ON 14X7.5 COMBEE WITH A 5 BLADE WARP DRIVE AND HAVE NO PROBLEMS RUNNING WHERE I WANT WITCH IS USALLY DRY.

 

[Anonymous]

i tried lots of tricks moving gas tank fwd. raising backend of motor. ect.
but what worked for me was a trim tab. it pops the boat up on plane
in an instant. worked for me.

 

[Anonymous]

Trim tab is a great thing , but climbing over stuff tends to make bend it like a cheap coat hanger

 

[DairymanNM]

I may try a trim tab. I won't be bending it because I have already learned my lesson when it comes to running dry. It won't! Next week I am putting on a new Edelbrock intake manifold and carb. We'll see how that does. I think I'll have a new motor by the time I am done fooling around with this darn thing.

 

[Anonymous]

ONLY OTHER THING I CAN SUGGEST IS PUT A LEVAL ON YOUR STRINERS LENGTH WISE AND LEVAL UP YOUR BOAT,THEN PUT YOUR LEVAL ON THE VALVE COVER LENGTH WISE,THE MOTOR SHOULD BE SLIGHTLY DOWN IN THE BACK,NO MORE THAN A 1/4 INCH.THE FRONT SHOULD NEVER BE LOWER THAN THE REAR.MINE IS ABOUT A 1/8 INCH DOWN IN THE BACK. HOPE YOU GET IT LIKE YOU WANT IT :wink:

 

[Anonymous]

one boat i built i made 2 small 6 inch wide 10 inch long trim tabs
one on both sides of boat.boy did it come up on top of the water quick
it also had 327 heavy old motor and would try to sink itself if i got on it
starting out before the trim tabs.

 

[Anonymous]

I'll try the level today and see what I get. I would guess that it's going to be ok because the boat is in proper order except for its need to plow through the water versus riding on top of it.