Hole Shot Power

[csl]

Curious if My 351 is needing an overhaul. Motor is running smooth and purring finally. Carb is freshly rebuilt and seems to be operating great. My only problem at the moment is that it doesn't have much hole shot power. If there are a few people in the boat, it takes too long to pull a rider up. Once on plane, it seems ok but still not like it should. Compression all around is 105-110 and motor has 840 hrs. Is this about the time for a rebuild or is there something I need to tink with more? I know props can make a difference, but it feels more like a power issue than prop. It also has a very slight amount of white smoke coming out of exhaust while cruising. Thinking it may just be getting tired in its old age.

[Jetlink]

How's your prop look? Any bad dings or nicks in it?

[villain]

Time for a rebuild. Compression should be 150ish.

[csl]

prop is great. The PO hit a stump in 07 and replaced everything from the tranny down. So its all brand new looking

[dirtydawg]

Time for a rebuild. Compression should be 150ish.

also timing chain/gears get worn and timing suffers causing power loss. I,d rebuild.

[Salty87]

rpms at wot?

take a look at your prop and see what you've got. rule that out before rebuilding. 840 hrs is nothing although the compression is a little low.

[csl]

as far as my rpms, i will have to check that for sure next time im out. can't give you an accurate answer on that now.

My prop is a four blade, 13/13. let me know what you think on that. Its in perfect shape. Thanks

[Supra_Comp]

I would suggest a rebuild. I just went through the same issue with my 85 Comp, could barely pull up a skier with 2 people in the boat.

I had 3 cylinders @ 108 and the other 5 @ 115. A tired motor will always run smooth at idle since it has hardly any compression to work against, but can be a PITA to get started sometimes.

Also, with a vacuum secondary carb setup the motor isn't creating enough vacuum to open up the other two plates so you are essentially running on half the cfm of air going into a tired motor....bad combo.

[wotan2525]

I think a rebuild should be the last thing you do after exhausting all other options....

What kind of RPMs are you pushing? When was the last time you did a tune-up? (Wires/plugs/points/rotor/cap/etc)

[csl]

I think a rebuild should be the last thing you do after exhausting all other options....

What kind of RPMs are you pushing? When was the last time you did a tune-up? (Wires/plugs/points/rotor/cap/etc)

I plan to be on the water tuesday night. I will watch the rpm's then. as far as a tune up, beginning of last year that was all done. I changed my plugs first of this year again because a couple had an external spark going on. Everything is running smooth, no real issue that I can find. Just lacking the power it should have.

[haugy]

Check your timing while you are at it. Improper detonation vs. fuel delivery can hurt you as well.

[chrisk]

What do you use the boat for primarily? Slalom? Wakeboard? Surfing? Tubing? Cruising?

If the answer is any of the above except purely slalom, go get a 13x11.5 prop, you might be pleasantly surprised. All the guys above are right, compression is a little low, and the motor is probably getting tired, but you wouldn't believe what a change in prop pitch can do. Especially if your 13x13 is OEM (old blade design).

[csl]

ok, spent the evening boarding and watching my rpms this evening. From what I'm seeing and if the guage is correct, my rpm's and speed are about the same as it climbs. As far as wot, my rpm's are at 3,300. Not very good. it takes a while to get there too. As far as what we have done to the engine, rebuilt carb last fall, tune up, adjusted timing and it is running the best since i've owned it. Just not the power it should. Hate to tear it apart when its purring so good, but may need a project for the winter.

[Hagman]

Start with a prop change. (1 to 1 trany)13x13 is OK for a 3 blade but for a 4 blade it’s a bit over pitch. Ask someone if you can brow there spare for a day. Call the prop shops in the aria and ask if they have a demo program. YOU DING IT YOU BUY IT. I have a 13 x12 fore blade I would sale for $175.

[Salty87]

As far as wot, my rpm's are at 3,300.

agreed. your prop is the main suspect at this point. you should be hitting 4400 - 4800 or something like that.

imagine riding a bicycle uphill in too high of a gear. that's what your engine is getting from your prop. it's bad for the engine and bad for performance.

[csl]

I just talked to Gregg at ACME Props and he backed up what you guys have said about the prop. His opinion is for our boats we should always use a 3 blade instead of 4 and that I am way over propped. I currently have an OJ 807 13x13. Here is what he reccommeded: Prop #913 13x10.5 .080 cup 3 blade. If my rpms are at 3,300, he said this should get them up over 4,000 plus give much better hole shot. Any thoughts???

[jasun]

Pull the trigger!

[jayschock]

I was having similar issues with my 88 comp after I bought it a couple of years ago. Thought it was just a dog and figured the motor was tired and old. Got into some rocks with the prop so I needed a new prop anyway. Stepped into a lower pitched ACME to give me some more power. Pulls like a champ now. It's like a different boat.

[tg0824SSVGG]

Hey jay, see you in a couple of weeks!!!


Todd

[DAFF]

Are you sure the secondaries are opening up on the carb??? This would explain the bad hole shot. Even with the 13x13 the old girl should rock out....

[matt k]

i have an 87 comp with an 800 hour-old 351 and the original 13x13 with a few nicks on the trailing edge, and it easily gets people out of the water, even with a boat full of people. A prop will probably get you what you want, but it most likely isn't the source of your problem.

[csl]

thats what I keep thinking. I am dragging my feet on a new prop so far. I might go ahead and get a new one, but I want to tink with everything I can to make sure the motor is up to par before moving on. I plan to take a tackometer ( not sure if spelled right) next time on water. See what its telling me. I will get this figured out yet. Thanks for all the input.

[SquamInboards]

thats what I keep thinking. I am dragging my feet on a new prop so far. I might go ahead and get a new one, but I want to tink with everything I can to make sure the motor is up to par before moving on. I plan to take a tackometer ( not sure if spelled right) next time on water. See what its telling me. I will get this figured out yet. Thanks for all the input.

You said the prop (among other things) was new in '07? A new 13x13 4-blade is probably a lot more prop than an old 13x13 3-blade that the boat had originally. Besides just having more surface area, newer props are made better and are more effective at pushing water which is exactly why you need less pitch or diameter, or both. Honestly I think you have to try a new prop. It sounds like you've done nearly everything on the tune-up side of things, I think it's well worth trying.

I went from an OJ handmade 14x16 4-blade (unknown cup) made in the mid-90's to an Acme CNC 12.5 x 14.25 4-blade .075 cup and my WOT RPM is the SAME. Hole shot and throttle response are noticeably better.

[TitanTn]

I agree with the prop idea. Your motor doesn't seem tired enough that WOT would only be 3300 if everything else is fine. There has to be something other than just the motor, and almost certainly it's the prop. The guys at ACME, Nettles, and OJ really know what they're talking about. Regardless, even with a rebuilt engine, the new prop will make all the difference in the world.

[csl]

yeah, we have tweeked the motor all it seems to need right now. I got my new prop today (acme 543). Thought I would be able to get the old one off with a gear puller tonight, but not happening. Can't wait to try this bad boy out. Plan to find someone with a puller tomorrow and get back on the water. We did play with the fuel screw the other night while boating and got the rpms up to 3,600 now. Will let you know the results soon hopefully.

[gogger]

I am just south of columbus if you can't find one closer you can borrow mine.

[gogger]

Did you get the prop pulled?

[csl]

Yeah, thanks for the offer though. Ended up heating the hub a little and a light tap on the back loosed it right up. Was a little nervous heating things, but it didn't take much. Plan on trying it out tonight. Can't wait!! What lake do you use around columbus? We usually head south instead of your way. I'm just north of Dayton.
here is a shot of the new vs old.
12747

[TitanTn]

Looking forward to hearing the results. I'm banking on a significant difference.

[gogger]

Deer creek reservoir or griggs. Both less then 30 minutes from home. Where do you go?

[csl]

Deer creek reservoir or griggs. Both less then 30 minutes from home. Where do you go?

Never been to either one of those. Our closest is Eastwood lake near dayton or CJ brown Near Springfield. Neither one is very good so we end up going to kentucky some.

[csl]

AHHH!!!! I'm pulling my hair out on this motor. We put the new prop on and took the boat out friday night. It did seem smoother and cleaner than the old prop, but barely helped the hole shot and didn't gain any rpms. We had three people in the boat. Later we picked up three more and couldn't even get out of the hole unless everyone was in the bow. So i am back to the drawing board after purchasing the prop. I will give a breakdown of everything and hopefully someone can answer some of this.

Here is what the boat is doing: Idles fine and seems to run very smoothly. On the hose, you can't tell anything is wrong. Can rev it up to 5-6000 rpms if you want, so I know the motor can handle it and is running good. When we put it on the water it starts up great, idles great. When starting up, it will occasionally backfire through the carb. When we give it throttle for the hole shot, it just can't build the rpms at all. unless everyone is in the front of the boat it can't hardly do it. Once on plane, it runs real well but it does seem to have a very small miss every now and then. We are also drinking the gas way more than ever before. It also has no top end, RPMs are only getting to about 3,300. and speed only to about 30.

I don't think it is a performance issue, but a fuel or distributor issue. Will welcome all feedback
Here is what has been done so far. Tune up was done a year ago. Last fall the carb was rebuilt by a local carb shop. Timing was reset this spring on the hose, but not under load. New plugs this year also. Just changed the fuel filter tonight and there was some junk in it. Also ruled out the Fuel Pump. Took it loose from the carb and shot it into a jar. It had plenty of power. Ruled out the Power Valve in the carb with the two adjustment screws. Also my carb guy put ball float safetys in during the rebuild. He said all new holley carbs have that and it saves the Power Valve. Not really sure were to go next.

Here are some questions
Will the secondaries open up on the hose, or do you have to be under load? I had to rev it up to 5,500 or more tonight to see any action out of them. May not be a real good test until in water.

Could my carb need attention again so quick?

If it is my distributor, how do I check it. I took the cap off and the rotor is not wobbly at all, but I don't know much about all this. I am not a mechanic at all and have learned most of this from researching this forum!!

The one other thing i can think of, is i know my foam is wet under the floor. I plan on doing a rebuild this winter. But I can't hardly think weight is it, because I've been in too many boats were we loaded the fat sacs and had a boat full of people and still had the power. Also we had an ok hole shot this spring, but something has changed.
Sorry about the rambling, but any thoughts would be awesome. Thanks

[Torque]

Hi,

If the engine backfires thru the carb, you have a timing issue. Could be one of two things, or maybe both. 1) the distributor may have slipped or been bumped accidentally. 2) the timing chain may be stretched or worn out. I'm betting on #1. Put a timing light on it and check it. Is it an electronic ignition system? Or just a points and condenser setup?

[92SupraComp]

If its points and condenser, replace them. Set your timing a 10 degrees before and enjoy. I set my CC to 10 degrees before TDC in summer 2011. Early summer 2012 went up to NH with family and did some skiing. Had 7 people in the boat and 1 skier behind, 8 total. It was a dog getting up but would get the skier up every time. Had 4 people in the back and other 3 up front. Got back to Keuka, found the timing was 1 degree after TDC!!! Set to 10 and good as new! But that indicates Im due for new points and condenser in the CC.

[csl]

First, it is an electronic ignition. Second, I do think I am getting somewhere. Its slow, but progress. After changing fuel filter again and cleaning the screen before the carb, it has a greatly improved hole shot now. I wonder if I have some serious junk in the fuel. We took the boat out and played with timing last night. The sweet spot seems to be advanced 10-12 from top dead center. My rpms still haven't gotten above 3,400 though. How far should timing advance when given full throttle? Also the only time it backfires through the carb is when you give it full throttle quickly. If you ease into it, it doesn't backfire.

On another note, now that I have a hole shot and can board that new prop rocks!! It has really changed my wake from before. Its bigger with much more lip. I am very pleased with the purchase now. The boat feels different at speed also. I do have one question on the prop. At takeoff and occasionally at speed there is a small thump. You can feel it more than hear it. It didn't do that before the new prop, but its not a vibration. Just an occasional bump. Any thoughts?

[dirtydawg]

dont know about the bump noise but dont over rule weight as the performance problem. water logged foam can be very heavy, and if your motor is getting least bit tired it will most definitely be a factor with hole shot. I recently added 700# of ballast and with a new 351 HO, Its noticeable. If I tried that with my old motor or had to many plp. in the boat it would take the length of a football field to plane out. Good luck

[wotan2525]

I disagree about the wet foam. It might prevent you from planing out quickly, but it wouldn't prevent your engine from revving up higher.

[csl]

From researching old posts and what I have learned by playing around with the boat, I wonder if my advance mechanism is acting up. We timed it at an idle on the water to 10 degree. What is the best way to time it? Also, it did advance when given throttle, but not very much. From what im reading, it should advance a good bit. How much? Don't know much about all this, but you all are helping me learn.

[Hagman]

The base timing should be set at around 8 to 10 Degrees before TDC @ 600 rpm . book is 6. Total should be 30 to 34 degrees. . I’m thinking that total timing comes in by about 2000 rpm or less. You can check this easy with a timing light . You should be able to turn the rotor a little by hand and it will spring back. If it doesn’t there is something wrong. You might have some broken springs on the weights under the points plate. Easy Fix.

[csl]

Ok so here seems to be my issue finally (I hope). Took my distributor to a local shop that has a diagnostic machine. When set at 10 degrees BTDC it only advances to 19 degrees. It also takes until 5000 rpm's to get that far. So it is definitely faulty. It is the old Presolite and he recommended just buying a new one. This one is old and wore out and can't get parts for anymore. So my question is what do you all recommend to replace it with? I know skidim has the Mallory distributors, but is that the best one to get? Also best technique on convince my wife I need to spend more money on the boat. Ha Ha

[villain]

It's easier to ask for forgiveness than permission.


Sent from my iPhone using Tapatalk 2

[csl]

ha, we can not only get boat info on here, but deep wisdom also!

It's easier to ask for forgiveness than permission.


Sent from my iPhone using Tapatalk 2

[villain]

Hahaha it has worked for me so far. But she understands that the boat comes first. Lol

[Hagman]

I have the same distributor it’s really simple the way it works.. Take out the plate that the points are mounted to and look at the weight mechanism . Make sure that everything is moving freely, clean and re-lube everything in there. There should be 2 small light weight springs in there. If the spring are to strong it will raise the advance curve to a higher RPM. Someone may have installed the wrong strength of springs . It will work with only 1 spring . I have over 1700 hrs on mine I drought it’s worn out it just needs some TLC. You can get a spring kit at Napa $10. 19 degrees sounds about right. You can do this in less than a hr.

[csl]

I have the same distributor it’s really simple the way it works.. Take out the plate that the points are mounted to and look at the weight mechanism . Make sure that everything is moving freely, clean and re-lube everything in there. There should be 2 small light weight springs in there. If the spring are to strong it will raise the advance curve to a higher RPM. Someone may have installed the wrong strength of springs . It will work with only 1 spring . I have over 1700 hrs on mine I drought it’s worn out it just needs some TLC. You can get a spring kit at Napa $10. 19 degrees sounds about right. You can do this in less than a hr.

If I can fix it that would be great, but I am confused. It will only advance 9 degrees and it takes 5000 rpms to do that. Shouldn't it advance 24 degrees or so? The springs seem very tight.

[Hagman]

19 degrees is stock advance. Set base timing to 10 degrees, the distributor will advance 19 degrees more total 29 degrees advance by 1500 to 2000 rpm . I’m thinking that the springs are to strong. Or it needs cleaning. Book is inspect ,clean & lube every 100 hrs.

[csl]

Now it makes sense. I will take a look. My mechanic said it wasn't worth me paying him to mess with this old one, but I may try to myself before buying new. Thanks

19 degrees is stock advance. Set base timing to 10 degrees, the distributor will advance 19 degrees more total 29 degrees advance by 1500 to 2000 rpm . I’m thinking that the springs are to strong. Or it needs cleaning. Book is inspect ,clean & lube every 100 hrs.

[csl]

Yeeaah Daddy!! I can't believe my boat. I dropped a new distributor in it today. Took it to the lake this evening to time and test. Set timing at 10 degrees and gave it a try. It jumped out the water so fast, i was hardly prepared. That was some of the best money I've spent on the boat yet. So with a new prop and distributor, I am purring. It has taken care of all the problems we were having. Thanks for all the advise and input, I learned a lot through this issue. Rpms at 4,300 and speed around 45

[DAFF]

Glad it all worked out. The good thing is you now know your engine and drive line much better than the average boater and will be ready for the next adventure with respect to issues on the lake. The thing to remember is to never give up and check the basics first.

[supra790]

Which Distributor did you end up buying ? I am having similar issues. A mechanic I talked to thinks the intake manifold the PO put on is wrong and not handling the fuel properly. I haven't looked at the timing yet, but after reading this thread its the next things on my list to do...

[csl]

The best price I found was through Summit Racing. I got the Mallory Marine Distributor. Part # ylm554cv. Couldn't be happier with the results. I did have my old one diagonsed before pulling the trigger on a new one. Timing was set right, but wasn't advancing near enough at takeoff. Good luck!!

[92SupraComp]

I recommend a D.U.I. electronic dizzy... 2 wire hook up... very simple dizzy... $350