Won't plane

« **on:** June 21, 2012, 04:31:32 PM »

I have a 20' dusky open bow with a stock 351w and a jacuzzi 12yj pump. I bought a pump off another fella from this site and installed it. The boat just feels like I'm trying to drag a house behind me. It has a tiny bit of whole shot but will not get up on a plane. Im only getting 2500 to 3000 rpms. I've never had a jet boat and I'm lost. I have double checked the boat for excess water and I have none. My fuel tank is in the middle of the boat. I don't really see a lot of bubbles behind the boat(someone said it may be cavitating) the previous owner had the same problem but the wear ring was junk on the pump that was in it. This new pump is in great shape. No nicks or anything on the impeller or ring. Impeller clearence is .28". I've tuned the motor up recently too. Only thing left is to pull the points dist out and go to a hei dist. I know nothing about points. Please help. Also I don't have a ride plate on the boat. Is that a problem? Thanks

« **Reply #1 on:** June 21, 2012, 04:41:54 PM »

you have a tune up or engine problem' you should be turning at least 4500, even more if it was cavitating

« **Reply #2 on:** June 21, 2012, 05:09:01 PM »

Do you know the size of the impeller?

« **Reply #3 on:** June 21, 2012, 06:43:15 PM »

Quote from: jim brock on June 21, 2012, 04:41:54 PM

you have a tune up or engine problem' you should be turning at least 4500, even more if it was cavitating

You need to get the engine "tune" completed first. Get help with the points or change to an electronic ignition distributor (I just installed a Pertronix FlameThrower distributor with good results). After you get the ignition corrected double check the timing then try again.

« **Reply #4 on:** June 21, 2012, 07:31:44 PM »

I don't know the size of the impeller but it's a b if that helps. Ok. Ordered a hei dist. Any recommendations on what to set the timing to? Thanks

« **Reply #5 on:** June 21, 2012, 09:18:45 PM »

I know Fords don't like as much total advance as you can get away with in a Chevy, so...

I'd try about 32-34* total at 3000 rpm to start. Your initial timing setting isn't as important as your total. If the distributor instructions say it has advance weights set with about 20-22 mechanical advance, set your initial to 10-12 and get it running, then get it adjusted to the high rpm setting.

Again I'm a Chevy guy so the numbers might be off a little

« **Reply #6 on:** June 21, 2012, 09:40:55 PM »

a small block should run up a higher RPM than a big block.....you should also look into the pitch chart of the jacuzzi impellers..i know that a small block should be running a B in a Berk but im pretty sure that a Jacuzzi is backwards...im new though so look into it. you could have to much load on the engine which could be your problem

« **Reply #7 on:** June 22, 2012, 05:49:34 AM »

Are you sure the carb is opening to full throttle.? make sure the carb is open all the way. bad tune up will pop or miss under acceleration. good luck.

« **Reply #8 on:** June 22, 2012, 12:21:33 PM »

How do I take some load off of the motor? The carb is opening full throttle now. It wasnt before but is now. It does pop and miss a little under acceleration. I just took it out and put a timing light on and watched it while it was in the water and my timing is jumping all over the place. So I think a new dist and a total carb rebuild may be the key. But I'm curious to know how to take load off of it though. Thanks!!!!

« **Reply #9 on:** June 22, 2012, 02:02:02 PM »

Quote from: Racerman16 on June 22, 2012, 12:21:33 PM

How do I take some load off of the motor? The carb is opening full throttle now. It wasnt before but is now. It does pop and miss a little under acceleration. I just took it out and put a timing light on and watched it while it was in the water and my timing is jumping all over the place. So I think a new dist and a total carb rebuild may be the key. But I'm curious to know how to take load off of it though. Thanks!!!!

unhook the driveline from the pump and run it on the trailer.

« **Reply #10 on:** June 22, 2012, 10:50:50 PM »

Quote from: ka0tyk on June 22, 2012, 02:02:02 PM

unhook the driveline from the pump and run it on the trailer.

X2

try locking out your advance on the dizzy and set it at 32* at 3k-3400rpm as stated above..

« **Reply #11 on:** June 23, 2012, 09:12:52 AM »

I would tune it on the water. and not on the trailer. if you can tune a car and drive it around the block to see if any improvements have been made. same thang with a boat. i know its a bitch but thats how ya do it.

Racerman16

Won't plane

jim brock

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