RicardoMarine
Gold Medal Contributor
Kim, according to earlier posts, the bore is standard (4.000”) and the stroke is 3.480”..... which keeps the displacement at 5.7L...... same as previous engine!
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After reading through all the posts, problem seems to be the "10-15 seconds" to get on plane and this quote "It takes longer to get up on plane once on plane tops out at 40mph @ 4000 rpm. The power band arc is at 4800. It will stand the boat up on launch but while trimming it losses that thrust."
Sounds like it will rev past 4000rpm the boat just won't go faster ..... Ventilating the props.
I don't think the drive is trimming all the way down/in......
I am the original owner of the boat and have been boating over 10 years. M&M is the builder. The trim was fine and all the way down. The post was inaccurate. The boat did not stand the boat up on launch...It launched with some porpousing less then original engine and took a while to wind up to 40 MPH at 4000 rpms WOT. Trimming, I could get it to 41-42 mph.
There is no growth and the bottom is painted.
Thank You everyone for trying to help here. You have been awesome.
Provided there is no snow or ice this coming weekend, I plan to drop the boat in the water to:
1) Try to test again with loose gas cap to test tank vent not clogged
If a fuel tank vent system was to become clogged, it would take a while before the negative pressure within the fuel tank could possibly restrict fuel pump operation.
2) Drain as much gas as I can and refill with 87 octane to dilute octane booster that was added.
Did you sense that the engine was undergoing Detonation during the tests?
3) I will re-verify outdrive is fully down.
Anything else I can test. I know nothing about engine internals or ECU's but willing to do almost anything other then change the duo-props which are not the problem.
At this point, I would ask the builder to once again verify the assembly specs.
Use a dial indicator and degree wheel and see if the camshaft is indexed correctly according to how the manufacturer intended.
Perhaps check cylinder pressures.
Ask the builder for an EXACT piston profile.
Ask him what he used for a Quench dimension.
And certainly take a good look at the Progressive Ignition Advance and the Total Advance @ the RPM in which the reading was taken.
Look closely at the MPI system.
Until you roll up your sleeves and get more deeply into this........ you will continue to be puzzled.
Several items:
1) Anyone on here is central to southern NJ willing to give me a private message and estimate to diagnose this?I have no ability or the tools to perform testing regarding timing lights, piston stops, crankshaft mounted degree wheels, etc. My builder is 800 miles away and spring is fast approaching. I don't have much after all this work but I also cant go without my boat2) Someone stated very early in this thread you must use a genuine VP Distributor cap and rotor or it wont work. Apparently, M&M used part number 3861987 which I found on several online sites as a direct replacement for VP part number 3858975. Could this be the problem?
I am extremely frustrated and the boat is like a part of my body. I just don't know what to do at this point.
I am extremely frustrated and the boat is like a part of my body. I just don't know what to do at this point.