Did you look down the throat of the carb to see if the throttle plate was perfectly vertical while the shifter was in the wide open position?
So I looked at it last night an feel like a momo I actually have a 2 barrel Rochester carb, on further investigation I checked the throttle plate it opens to wot position an closes all like it should, I did take the flame cover off the carb an found out my choke is not opening up all the way once the boat is warm, do I confident that is causing the way it acts after trolling. But for the not hitting over 3900 rpms I do not no
Also don’t know if this will change anything but I have a Pertronix electric ignition on it an i am going to change the old coil (original) With a flamer thrower 40011 will that help with the rpms?
Not really. Need to change the pitch on the prop. Basically in auto term that is your final gear ratio, your running to big of a prop to get the top rpm. If you read up on it you will see what different pitches will do for hole shot and wide open speed. Sent from my SM-N960U using Michigan Sportsman mobile app
So which size should I try? From what I read an been told don’t know if it’s accurate maybe you can help out, but I got told that the 15x15 should make the boat scream? Maybe it’s not achieving what it’s capable of due to being a Michigan wheel aluminum prop?
200 rpms per degree of pitch. I would probably try a 17 pitch first. The lower pitch number will also decrease speed at times, but increase hole shot. Alot of the boats went larger pitch trying to get a little speed Se a 15 pitch moves 15 inches per turn While a 21 moves 21 inches. That does not include slippage that all have. You may be able to find a marina near you that will loan out a prop. In addition stainless steel will have better performance than aluminum. Sent from my SM-N960U using Michigan Sportsman mobile app
With limited information i would not assume prop is the problem.I would contact Crestliner and find out what prop came on boat when shipped,build sheet should be on record.If it is original prop(pitch/dia) only then can you know if engine or hull weight is the problem.A good engine diagnosis could tell you of other issues with the engine its self.Might take the guess work out of solving your problem..
Agree with textox. Too many questions about fuel, spark and air before trying another prop. Questions remain unanswered about the prop also, such as did the boat ever perform acceptably in the current owner’s possession.
Yes Kroppe,Too many systems come into play there,timing,compression,carb tune ,fuel pressure,and the possibility of water in the fuel or a leaking head or more commonly an intake gasket.Lots more to consider than the prop..
I have a 1986 Sylvan with 4.3Cobra outdrive, I put a pertronix electronic ignition in it. It worked fine at first, then I took it to the Bay. It wouldn't rev over 3000 rpm's. Found out one of the magnets came off , so it was only hitting on 5 cylinders. Put the points back in it and it redlined. That is a glass 19' boat will do over 45 gps mph. The magnets are under the distributer cap, a piece of green tape is all that holds them in place,you might want to look there. Sent from my iPad using Michigan Sportsman mobile app