performance problems

[jee70611]

Hi everyone. I recently bought my first boat. It is a 1979 Zephyr with a 1979 35 Johnson on it. The model number on the motor is 35EL79A. Does anyone know what the compression should be on this particular motor. I have measured it and there is 125psi in one cylinder and 119 in the other. I've been trying to figure out why my boat doesn't have a very good hole shot. It is a small 14 foot fiberglass trihull that doesn't have a windshield or any extra wieght like that. I get good top end out of the motor but it won't even come out of the hole enough to pull a kneeboarder. I believe the motor has been rebuilt, or at least reringed within the last 30-40 hours because I pulled the head to decarb it and well, there wasn't hardly any in there and the hone marks were still visible. I have also noticed that the top crankshaft seal is leaking quite a bit of fuel and probrably loosing vacuum. I plan to change that soon. It is very clean and seems to run great. Starts as soon as I hit the key every single time. I have suspected the 10.5" X 11" prop, timing, and fuel supply as possible problems. Does anyone know where I reference the timing on this engine. My best guess is the part that sticks up on the starter. There are no other marks that would even come close to being right. I did advance the timing while on the water last time and got much improved performance. The only problem is that when I checked it against the part on the starter it showed 36 degrees and the limit for this motor is 30 degrees. I also should say that I did a long trek all over Norris Lake in TN and after burning six gallons of gas I checked the plugs and they were light brown with some very small black dots on them. I was using Champion QL77JC4 plugs. I can't hardly find any information on the manufacturer of my boat either. They were based in St. Augustine, FL. I found a website for Zephyr boats but they seem to be a new company. <br /><br />The Questions I have are:<br /><br />1. Is my compression OK?<br />2. Should I suspect prop as a major problem for no hole shot?<br />3. Are my spark plugs normal?<br />4. Where is the timing mark for my motor?<br />5. Would the seal leaking cause lost hole shot but not hinder top end as much. <br />6. Has anyone ever heard of my boat? If so would you please let me know as much as you can.<br />7. Was $800.00 too much or did I get a steal?<br />8. What is the gear ratio of my lower unit?<br /><br />I know you guys haven't seen my motor or boat but any information would be greatly appreciated.<br /><br />Thanks, <br /><br />James<br /><br />PS: I did buy a manual but it doesn't have the compression specs.

 

[MGuckin]

Re: performance problems

Congrats on your first boat. Good to hear you bought a manual also. Definately starting on the right track. Book says anything over 100 should be ok as long as doesn't vary by more than 10% between cylinders. It doesn't sound like a prop problem with the pitch you have I would think it would have a top end problem rather than a hole shot problem. Try your trim at different settings. If no T&T try middle hole first. Farther away from the boat it is trimmed, the more hole shot you should have. If too far, you might have a planing problem. Also check your motor height where it is bolted to the transom. Cavitation plate should be even with the bottom of the boat at the transom. Plugs sounds normal. Some deposits are to be expected. Plug should be QL77J4 @.040. Stationary timing reference mark is on the starter. If you are getting 36 instead of 30, try checking your carb linkage. It is all tied together. <br />Mike<br />

 

[jee70611]

Re: performance problems

Thanks for the reply MG. I already adjusted the carb linkage to get it synchronized correctly. I have to have the motor trimmed all the way down to the bottom hole to get the boat on plane without having to walk up to the front. The cavitation plate is a little too low I believe. I will probrably have to get a jackplate to raise it up enough though. I will try to get that seal changed, and see if I can move the motor up some before this weekend so I can test out the changes and set the timing. Thanks again for the great info. <br /><br />James

 

[steelespike]

Re: performance problems

If you have to raise the motor a little try what we used to call a rev stick.A 1/4" or 1/2in stick<br />between the clamp and the top of the transom.<br />just enough to get the cav. plate at the right spot.Be sure to balance your weight out.Too<br />much stern weight will slow your holeshot a lot.<br /> You could try a whale tail or dolfin.they are very good for hole shot and your boat will stay on plane at lower power. They do reduce top speed slightly but I cant tell the diff. on my boat.<br />Some fiberglass boats are pretty heavy.<br /> that can be a problem too. Good luck, Spike