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power issues on 400 smb direct drive

Posted: Mon Sep 21, 2015 8:51 pm
by papasmurf
I have a 400 smb direct drive with a 600 Edelbrock carb with rv cam and a new 6 blad warp prop. I am only pushing about 2000 rpms. Just wanting to know if i need to change my carb or what else i could do to get 3000 rpms.

Re: power issues on 400 smb direct drive

Posted: Mon Sep 21, 2015 9:12 pm
by keebo
What's the length of prop, smart sense would say adjust the prop to where you can turn the 3 k. Sounds like just to much prop to me.

Re: power issues on 400 smb direct drive

Posted: Tue Sep 22, 2015 1:55 pm
by Olf Art
keebo wrote:What's the length of prop, smart sense would say adjust the prop to where you can turn the 3 k. Sounds like just to much prop to me.

Yup. Use the prop as your rev-limiter. Six blades may be too much prop for a DD.

Re: power issues on 400 smb direct drive

Posted: Tue Sep 22, 2015 2:00 pm
by papasmurf
It's a 77in from tip to tip. Ok thanks guys.Do I need to take two blade off yall think and just make it 4 blad?? Or just play with the pitch

Re: power issues on 400 smb direct drive

Posted: Tue Sep 22, 2015 2:20 pm
by SthrnStyle3
I'd say both.. Try it as a 4 blade and set the pitch to your desired rpm's. A 77in 6 blade is way too much prop IMO..

Re: power issues on 400 smb direct drive

Posted: Tue Sep 22, 2015 2:56 pm
by scottyroll
Six blades at that length is too much.

Also, I've heard that a 4 blade could cause harmonic problems for the crank if not set up in a bow-tie pattern but that was in regards to aircraft.

Not quite sure if there would be a difference but wanted to share.

Try and get at least 6degrees of pitch in each blade or else it won't perform efficiently.

Re: power issues on 400 smb direct drive

Posted: Tue Sep 22, 2015 8:45 pm
by papasmurf
Ok do they make a tool to check ur pitch with. If so where can I order from??

Re: power issues on 400 smb direct drive

Posted: Tue Sep 22, 2015 9:26 pm
by glades cat

Re: power issues on 400 smb direct drive

Posted: Tue Sep 22, 2015 9:36 pm
by Deano
This is the one I have, and use that little guy all over the place.

http://www.ebay.com/itm/iGAGING-DIGITAL-ANGLE-CUBE-ELECTRONIC-LEVEL-SENSOR-BEVEL-GAUGE-TRIPLE-MAGNETIC-/281221180493?hash=item417a16ac4d

Warp dive makes a protractor for that purpose, but I can't imagine it being as versatile.
There are many that will work, but something at least similar is what I would get.

Re: power issues on 400 smb direct drive

Posted: Tue Sep 22, 2015 9:38 pm
by Deano
And there's more confirmation I need to learn to search and type faster. :lol: :lol:

Re: power issues on 400 smb direct drive

Posted: Tue Sep 22, 2015 10:08 pm
by papasmurf
Ok thanks guy

Re: power issues on 400 smb direct drive

Posted: Thu Sep 24, 2015 6:56 pm
by papasmurf
Do you guys thing i need to cut my prop done to 73" or 72" to make the motor push the boat good?????

Re: power issues on 400 smb direct drive

Posted: Fri Sep 25, 2015 12:44 am
by Olf Art
Don't go cuttin on the prop ..... take two blades off of it and try it as a 'bow tie' arrangement first.
Cutting on props can raise a whole new set of problems.
Stay in touch ..... we'll get you there.

Re: power issues on 400 smb direct drive

Posted: Fri Sep 25, 2015 9:07 am
by ALLRED520
A buddy of mine a 72in 5 blade and spins it 3k all day same power plant you have i would agree with the other guys to much prop i think my buddy is run 7-9 degrees on his warp

Re: power issues on 400 smb direct drive

Posted: Fri Sep 25, 2015 9:32 am
by ALLRED520
Sorry for the grammar i hate these new phones

Re: power issues on 400 smb direct drive

Posted: Wed Sep 30, 2015 4:34 pm
by papasmurf
ok guys took two blades off and changed the pitch some. Boat run alot better but only got 2400rpm. Im going to try and run the boat some this weekend and change the pitch some more. Or do i need to leave it alone and stay where im at. the prop has a lot adjustment where the props can move in to a 72'' i think i have not tired it yet.

Re: power issues on 400 smb direct drive

Posted: Wed Sep 30, 2015 4:37 pm
by papasmurf
And Where do i need to place the pitch gauge at on the props????

Re: power issues on 400 smb direct drive

Posted: Wed Sep 30, 2015 6:14 pm
by Gangreen
6 blades is not too much. It is alot but can be adjusted and ran. Try 7 degrees it should get you 2800 ish. If not you engine could looking at. My brother is spinning a 6 blade 72 inch at 2800 at a tight 7 degrees on a 383.

Re: power issues on 400 smb direct drive

Posted: Wed Sep 30, 2015 6:20 pm
by Olf Art
Gangreen wrote:6 blades is not too much. It is alot but can be adjusted and ran. Try 7 degrees it should get you 2800 ish. If not you engine could looking at. My brother is spinning a 6 blade 72 inch at 2800 at a tight 7 degrees on a 383.

Yessir, but this man is trying to spin a fan that's 77 inches in dia. HUGE difference!

Re: power issues on 400 smb direct drive

Posted: Thu Oct 01, 2015 8:34 pm
by Gangreen
2.5 inches is not that big of a difference since my brother is running a 383 to a 400. I have ran alot of direct drives with warps. He should be able to bring the pitch down to 6 and run fine. If not the engine has problems or short of horsepower.

Re: power issues on 400 smb direct drive

Posted: Thu Oct 01, 2015 9:49 pm
by Olf Art
Gangreen wrote: I have ran alot of direct drives with warps. He should be able to bring the pitch down to 6 and run fine. If not the engine has problems or short of horsepower.

Gangreen, I'm beginning to think it might be a tuning problem also.
Papasmurf, are you running a vacuum line on your distributor? How much timing advance are you seeing at 2,400 rpm?

Re: power issues on 400 smb direct drive

Posted: Fri Oct 02, 2015 7:08 am
by papasmurf
Yes I have vacuum line hooked up. And on timing is advanced 10 degrees. The 400 is bone stock rv cam, 600 carb, and aftermarket stock distributor.

Re: power issues on 400 smb direct drive

Posted: Fri Oct 02, 2015 7:18 am
by papasmurf
Do put the pitch gauge on the tip of the blads or in middle of the blads.??????

Re: power issues on 400 smb direct drive

Posted: Fri Oct 02, 2015 1:55 pm
by Davie GSO480
First get the engine level...VERY important ...........use the prop plate. as reference...

Then measure in like 1 inch, put blue tape at the 1 inch mark,,,,,,measure each blade the same, 1 inch in from end.

Take a pitch reading........so you know where you are at now.

each degree will make about 200 rpm's or so diff......

so if your at say 11 deg take 2 deg out,,,less pitch=turn 400 more....thats + or -......you will have to see for your application.

Re: power issues on 400 smb direct drive

Posted: Fri Oct 02, 2015 2:00 pm
by Olf Art
papasmurf wrote:Yes I have vacuum line hooked up. And on timing is advanced 10 degrees. The 400 is bone stock rv cam, 600 carb, and aftermarket stock distributor.

OK, we might have hit on something important here. Remove the vacuum line to the distributor and plug both ends where it connects. Now, with the engine running, advance the distributor to 25-28 degrees and see what your rpm increases to. If it does, then this may be a timing issue that's easily fixed. Just a thought .... try it before you re-pitch anything, and if it does increase, don't rev it past 3,000 rpm for now.