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Need help with my RPM's

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Robby Bondurant

Well-known member
Okay, here's the deal. I just got my boat done, I got all the valves adjusted, and set my 5 blade warp drive prop at 10 degrees each. I put it in my pasture today and tried to see what it would do.

When I tried to run it wide open it would only turn up to 2100 RPM's at the most, and I know that's not right. 10 degrees should not be too much for that engine at all but i changed them to 8 degrees each and that didn't change anything. The engine was running nice and smooth but it just wouldn't turn up.

When I tried to turn it up it wouldn't even budge, even with my buddy pulling on the front. But I know it wont let loose until I get it up to more RPM's.

I was just wondering if adjust ing the carb (the fuel/air mixture) would help this out? I'm thinking this is a stupid question but I just wanted to ask the experts. If this is what I need to do, how do I know when I have it set right?

Any help is greatly appreciated, thanks, Robby.
___________________________________________________________

I know I will probably get asked what kind of boat I have and all so...

12'8" by 7' glass hull with a dd sb 350 bored 30 over with a roller cam, edelbrock intake with a edelbrock 650 carb.
 
well I know there going to ask you for more details on what motor and every thing else. I am in a similar situation and every one has been great on the information. Good luck.
 
I only had 8 and 10 degrees in my warp drive with a gear box so it sounds like you have too much pitch. what size is the prop and how big of an air filter do you have on it. have seen in the past if they are too small they won't let enough air in.
 
It's only a 68" 5 blade and when I changed the pitch from 10 to 8 it didn't even change the RPM's at full throttle. I believe it is a 12" air filter.
 
10 degs should be fine how thick or tall is the air cleaner. take it off and see if it will run any better. if not play with the timing that thing should spin up good
 
Might check your throttle linkage to make sure that
its opening up all the way. check the simple stuff first.
 
YOU BROKE IT RIGHT ! YOUR CARB ALL WAY THE OPEN RITE! TIMING RITE ! I HAVE HAD TWO OF CARBS LIKE THAT ! DIDNT LIKE THEM !LOST POWER ON BOTH ! BUT DIDNT KNOW HOW TO SET THEM UP !GO BACK AND DOUBLE CHECK TIMING AND YOUR CARB ! THE SIMPLE STUFF ALWAYS GET IN THE WAY ! MAKE SURE YOUR ADVANCE IS WORKING ! NEVER HAD A WARP DRIVE SORT OF LOST THERE ! IT WOULD HELP IF YOU POST CAM SPECS ! MY BUDDY OVERCAM HIS DIRECT DRIVE IT WOULD OVER 2200 HIS CAM CAME IN AT 2800 SO IT WAS A DOG ! UNTIL THE BOX ! :shock:THE EXPERTS WILL SHOW UP !
 
My guess would be to check the throttle linkage first, remember Fuel -Air -Spark- Timing. I'm running a 2.37 gear box with about 400+ H.P. 6 Blade warp set at 16 degrees turning 5500 RPM.
 
10 degrees is too much for a DD 350.

My built 383 turns the exact same prop you have 3000 rpm at 7 degrees. At about 10 degrees, it only turned 2700.

I'd drop it back to about 6 degrees and go from there. You should pick up some RPM.

You should have noticed an increase when you changed it to 8 degrees though....

Are you measuring the pitch at the tips? And is your hub level when you are adjusting?

Should be easy to check for throttle binding, just grab the linkage at the carb and rotate it all the way open.

Need to know your cam specs and how much advance you are running. Also be nice to have come vacuum readings and fuel pressure.
 
Chris- I did take the air cleaner off and it didn't change a single thing!

K-Mac- I have been pushing on the throttle at the carb so I know I'm getting full throttle, so I know i'm not loosing it in the pedal.

Fatboy- I know why someone would get rid of one of these, they are the most complicated pieces of equipment, if you've never delt with one. I know that if you can get them set right, they run good, but the problem is getting them set right.

Red- I know if the problem were to be the prop, then I would have noticed something when I turned it down from 10 to 8. It should have at leaast made a little bit of a difference. I did measure them at the tips with the blades straight out to the side running parallel with the ground. I don't have any clue on the cam specs or the vacume pressure. I know my electric fuel pump is a 2.5 to 4 psi pump, which is in range of the carb specs.

I did set the advance at 32 degrees, thats what I was told by a friend that he runs all his at. After making sure the timing was set right, I played with the lean/rich screws on the carb and still didn't see any change, except for the idling sounded crappy. But I got the timing set and can get it to idle great and it sounds great when I turn it up, but it just isn't turning up those RPM's. I worked on it from 7:30 till 11:00 tonight and couldn't get anything but 2150.
 
Hi Robby Bondurant


Seems everything's alright except for that power at the top. Hmmm...

Fuel and air were also checked.... now, just maybe, try to double check your valve clearance and see how many mils you have there. Usually, the problem arises where the tinkering was done.

Leo
 
I would take the pitch out...see what it does for no load rpm....then go from there.

Grant
 
if you can look while the boat is running wide open... we had one carb where the secondaries were not opening. Might just double check that.
 
well here is what my motor was doing. Rev up to 3200 when cold or low humidity in the morning then 25 to 2700 during the heat of the day. I only turning a paddle 72 34 wood don't know how that compares to yours. I will be changing my intake and adding a 1" plastic carb spacer this week end. If this corrects the problem I will let you know. Like some have said I went thru everything down to spark plugs. One thing check fuel filter and carb filter just put the boat together or if it sat maybe some blockage from old fuel or what ever in the tank.
Good Luck I know the frustration
 
Your pump is supposed to be 2.5 to 4 psi, but is it really giving you that?

Also, if your cam is not giving you enough vacuum, that can mess up the carb tuning

Need more data to know which way to go next, so get with a buddy that has a vacuum gauge and a fuel pressure gauge
 
Set your pitch to 4 or 5 degrees. You could have soo much pitch that your motor and prop is hitting the wall. Check your timing, on a 4.00 bore SBC motor you can run 32 OR 34 degrees. Anyway set it at 4 or 5 degrees then you should be able to turn around 2,800 TO 3,000.
 
I played with the timing again when I got home today and turned the distributer around till it started to sound like crap, brought it back some and set it right there and it seemed to do fine. I changed the pitch to 5 degrees and it turned up to 2900, but it doesn't seem to have any knid of push at 5 degrees. I know not to be expecting too much, but it should have more than what it's showing me. I guess I just have to keep burnin gas and playin with it! Thank ya'll so much so far and keep it coming, everything is very helpful!
 
That's about what I thought it would turn at 5deg. Remember most stock 350 SBC don't even make 300HP. The rotten years 1975 to 1985 barley made 250HP and that's @ 5,500rpm. So if you have a 250HP to 300HP SBC 350 only turning 2,900RPM at best your making between 110 to 160 Horsepower. The conventional small block 350's don't make much torque or power.
 
I know it's not goin to be a power house but I know quite a few people that have dd 350's that run great, push great, and can run ground. So I was just wondering if I had done anything wrong that would be causing a problem.


Right now my engine is set where the back end is higher than the front. I've been told that I need to put the back end lower to even consider to be able to run ground. If I lower the back end, how much lower should I set the back from the front?

Thanks for everything!
 
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