56' MY can it plane>

[q240z]

2200 port 2250 starboard my mechanic tested the tachs to see if they were right with some kind of instrument on both engines they are sorry I'm not a mechanic so don't know what he used ...my mechanic is Wayne Hannaseck from Anclote Diesel Specialist Tarpon Springs Fl. and he is one of the best...lol

Don't sweat it, Joe. You don't need a mechanic to do this test. But it's not entirely clear if this was a "no load WOT" test he did. By "no load," we mean "in neutral." Photo tachs are the most accurate, but you can do this test yourself by just putting it in neutral and running the engines up to full speed. Make sure the engines are fully warmed up (you can even do this at the end of your next day of running). Let us know what you see on the tachs when you put them to full throttle (Wide Open Throttle = WOT) in neutral. If, in fact, it only goes to 2200 and 2250 in neutral, that'll be a great starting point for the gurus here to help you diagnose it.

It could be as simple as having a Detroit mechanic set the governor and maybe adjust the rack. That's a practically a maintenance item. It'll just help to be very specific with the data you provide to help avoid confusion and assumptions that may or may not be accurate.

[kjcampos]

Don't sweat it, Joe. You don't need a mechanic to do this test. But it's not entirely clear if this was a "no load WOT" test he did. By "no load," we mean "in neutral." Photo tachs are the most accurate, but you can do this test yourself by just putting it in neutral and running the engines up to full speed. Make sure the engines are fully warmed up (you can even do this at the end of your next day of running). Let us know what you see on the tachs when you put them to full throttle (Wide Open Throttle = WOT) in neutral. If, in fact, it only goes to 2200 and 2250 in neutral, that'll be a great starting point for the gurus here to help you diagnose it.

It could be as simple as having a Detroit mechanic set the governor and maybe adjust the rack. That's a practically a maintenance item. It'll just help to be very specific with the data you provide to help avoid confusion and assumptions that may or may not be accurate.

good morning q240z...hey my friend used to have a 240z when they first came out beautiful car...my mechanic is a Detroit guy and we did do a sea trail just in June because he had to come to Titusville Fl. to clean my heat exchangers and my intercoolers which were dirty so at that point in the sea trial with the props just done in May... was a good time .....we were in the river there flat calm with 340 gallon of water ...which i have now emptied about 2/3rds fuel tank full maybe 50 gallons in holding tank and my 13' Boston Whaler on top we ran it WOT for over half hour to make sure temp didn't come up and still only 2200 and 2250 on engines we were out for about 1 1/2 hrs on the sea trial and when back at the marina we did the no load in neutral and it still said 2200 and 2250....but i will ask him about the governor and the rack thing you mentioned to see what he says..i will try the no load again on our next move right after this storm goes by and we continue our trip back home to Florida..

[saltshaker]

If the no load RPM is the same as the loaded RPM then that explains why the speed is sonlow and you didn't see any change when you tweaked the props. If you aren't hitting full RPM you're not getting full HP out of the engines. Did the mechanic explain this to you and did he investigate why the engines aren't hitting factory spec? Why do a no load test and not look for the problem when the engines are nearly 300 RPMs light? I had to push the mechanics at a major Detroit dealer to do a no load test after having engine work done. Boat was running slow and only hit 2100 RPMs. That's how they planned to return the boat to me until I said no way. Turned out they set the governor up wrong. I went from 2100 RPMs and 19kts max to 2350 RPMs and 27kts max. You need to ask your mechanic why the no load RPMs are so low. Most likely you wasted a fair amount of money tuning your props the wrong way. Strange that both engines are low unless they were intentional set up that way to prevent high load usage.

[kjcampos]

If the no load RPM is the same as the loaded RPM then that explains why the speed is sonlow and you didn't see any change when you tweaked the props. If you aren't hitting full RPM you're not getting full HP out of the engines. Did the mechanic explain this to you and did he investigate why the engines aren't hitting factory spec? Why do a no load test and not look for the problem when the engines are nearly 300 RPMs light? I had to push the mechanics at a major Detroit dealer to do a no load test after having engine work done. Boat was running slow and only hit 2100 RPMs. That's how they planned to return the boat to me until I said no way. Turned out they set the governor up wrong. I went from 2100 RPMs and 19kts max to 2350 RPMs and 27kts max. You need to ask your mechanic why the no load RPMs are so low. Most likely you wasted a fair amount of money tuning your props the wrong way. Strange that both engines are low unless they were intentional set up that way to prevent high load usage.

Jack i can't be sure if he looked at the governor and it is set lower he is the one who told me that it may be the props ...i didn't mind to spend the $$$$ getting them tuned i don't know if they were ever done and they were pretty gritty and they needed it and now i know they are done right now..but you guys have given me some questions to ask my mechanic i Trust him very much i don't let anybody else touch my engines...

[oscarvan]

No load WOT comes first, before props, period. If your not getting the numbers the first problem is in the engine room, not outside. Start there, process of elimination.

Nothing personal, but how can you tell your mechanic is the best there is if you don't know the business yourself? So far he's not coming through. Things that make you go hmmmmm.....

[saltshaker]

Jack i can't be sure if he looked at the governor and it is set lower he is the one who told me that it may be the props ...i didn't mind to spend the $$$$ getting them tuned i don't know if they were ever done and they were pretty gritty and they needed it and now i know they are done right now..but you guys have given me some questions to ask my mechanic i Trust him very much i don't let anybody else touch my engines...

Problem is you tuned them down to gain RPMs. If the engines are the issue you most likely tuned them the wrong way and will need to re-do them to get the speed back. Props have nothing to do with no load RPM so you should confirm the no load performance before trying anything else. Not sure why he would tell you to tune the props if no load is that low. I've had 3 different excellent Detroit mechanics skip the no load test and blame props or bottom condition when we were short on RPMs. Each time I insisted we did it we found something wrong with the engines. Most likely yours is something simple such as tune or throttle linkage. Very possible you have one or more bad injectors unless the mechanic tested each before he installed them. Most don't and as anyone here will tell you, the failure rate on them right out of the box is probably around 30%. Tim Powell had several bad injectors on both engines after doing a major on each. They changed them several times before getting all 16 right. If he used Detroit Reliabilt injectors I'd bet good money several aren't firing properly.

[kjcampos]

hi Oscarvan...i don't know if he is the best but i have a very good friend of mine who has a Hat 53' and he is a good mechanic and he uses the same mechanic to work on his DD when he can't figure out whats wrong...and IF my engines are Tuned down it wasn't me it may have been one of the PO ...i'm #6..but I'm sure my guy would have checked that ...now Jack as for the injectors i don't know what brand he used but i know he did check them after he put them in because i was there when he did and i specifically asked him that question and he tested them all and they were all working...but i am making a list of questions to ask him....

[q240z]

Think of it like this: if your car wouldn't do freeway speeds or rev above 3000rpm in neutral, and a mechanic checked it out and told you to buy a new set of tires, that'd be odd since the state of the tires has zero to do with the engine not revving in neutral. Even if, in fact, it was time to get new tires, that still doesn't have anything to do with the fundamental engine problem.

I wouldn't go back to a mechanic who did that, even if he came very highly recommended.

[kjcampos]

Think of it like this: if your car wouldn't do freeway speeds or rev above 3000rpm in neutral, and a mechanic checked it out and told you to buy a new set of tires, that'd be odd since the state of the tires has zero to do with the engine not revving in neutral. Even if, in fact, it was time to get new tires, that still doesn't have anything to do with the fundamental engine problem.

I wouldn't go back to a mechanic who did that, even if he came very highly recommended.

sorry guys I'm not changing mechanics but i will put forth the questions that the forum has mentioned and go from there ....i would love to know when George owned it what his WOT RPMs were maybe he knows something ...