Marinette Boat Forum

I have had a problem ever since I rebuild my boat. The starboard engine is weaker than the port. The Port engine I rebuilt. I had it bored to .30 over (because of cylinder rust). And had the valves dressed up. The starboard engine had been sitting for 6 years with water in the oil form a blown exhaust manifold. The cam was rusted up and the pistons seized up. I purchased an Grooms re-manufactured long block. Both engines have new Mallory distributors and New Carburetors. I cannot hear any differences in the engines. The Starboard engine seems have a less powerful in noise.

Wide open throttle Port 3750 RPM Starbord 3400

Wide open throttle with other engine idle Port 3100 Starboard 2700.

At synced at 2500 RPM the Starboard throttle significantly more than the Port. I have a flowscan the Port engine is using 2-3 gallon per minute more gas.

I have swapped the carburetors - no change

Played with timing - no change

I am going to pull the spark plugs and inspect each one and then do a compression check.

I am worried about the quality of the re-man engine. The valve leaking or an cheap or wrong cam grind.

Has anyone else have one engine stronger than the other? Is it the Starboard reverse rotation?

Just went through that with Mr Port. In its case, a plug wire (or two) was bad. (And when I changed the wires, one lead fell off. Doh!)

Here's what to do (and it won't be pleasant): Run the boat hard, then shut the motor down as fast as possible--NO idling allowed! Then, soon as it cools down, pull all the plugs and eyeball the colors. If they are all similar, fine; if one or two are different colors, there's where to start looking.

Jeff

PS: The 'mechanics' at my former marina switched two plug wires (not hard to do considering the crappy way Mopars are wired). Motor popped a bit planning off and was down about what you are seeing. Cost me a whole bunch of effort trying to figure out why, and didn't do the motor much good either.

That happened to me on my run from the launch point to the marina. The starboard would not heat up properly. The starboard lever was way ahead of the port lever. I went to install a new T-stat and found the housing bolt was loose. Tightened it and the engine heated up just fine. In the past I had problems with the ignition. I learned to repair my old distributers and set the timing.

As the other posters suggest, do the simple things.
While the engine is idling, wiggle the spark plug wires at the plug and the cap.
Check your distributor cap and rotor fit.
Look for carbon build up under the distributor cap.
Check the rotor for carbon build up.
If your running the Chrysler electronic ignition, check the magnetic pick up gap. Check to make sure the reluctor is solidly placed with two pins.
If your running the weight advance distributor, check the weights to make sure they are free and moving. Verify the distributor springs are the same strength on each motor. Weak springs equals too much advance. Strong springs equals less advance.
If your running vacuum advance, check your vacuum pressure at the distributor. Low vacuum equals less total advance at WOT.

Every year, I pick through the motor for a few hours looking for obvious stuff. Saves headaches during the fun times. Happy boat = happy wife.

If you're doing a compression test, your should also perform a leak down test. A compression test tells you the dynamic compression. A leak down test will identify leaking valve guides or seals.

Eric

My boat also had spark plug wires incorrect. Be sure you check firing order is correct on ignition cap. Trace all wires!

Let us know what you find lol

When I rebuilt the PORT and installed a reman in the STARBOARD I installed new Mallory marine distributors with Magnetic breaker less ignition, Mallory Coils , new plugs and wires. They now have 100hr them. Checked compression 125-135 PSI. Looked at the plugs OK. Triple checked the wires and firing order.

@#$#^$#%^@$# I blew my ignition module in the distributor. I unplugged the distributor when checking the compression. My mistake was I pugged the distributor back in with the ignition on. $100 Amazon am my motor is down till I receive the new module.

I think the difference may be due the remanufactured engine. The remanufactures re-grind the old cams. If it is not done correctly can distort the lift, duration or timing of the valves.

Sorry to hear that--I've oops a few things in my time as well.

I'm still doubtful that you have a bad camshaft, but.... It happens. Get back to us after the shipment arrives.

Jeff

Hi guys I have been having problems with my port motor stalling at idle and popping back through the carb under rapid throttle advancement, done a lot of checking and finally pulled the valve covers and no. 8 exhaust valve is not operating, flat cam lobe. I was wondering where to get a re-man. marine 318 anybody have good experience with suppliers Thanks

Harry - you'd do better to start your own "thread" with this query. Doing that keeps the forum more organized. You posted in the right department but hitchhiking on another post veers us off topic and make user interaction more difficult. Thanks for doing that. (meanwhile, I got Jasper remans when I need engine replacement long, long ago).

Harryb, Jralbert is right. Forum etiquette requires a new thread. Thanks Jralbert for keeping us on task. Welcome Harryb welcome to our forum, we will help you in the new thread.

FYI on cam lobes....you guys MUST add zinc at every oil change http://www.amazon.com/Zddp-Maxx-Shippin ... B003MAG004

Just sayin"