new boat, some questions on 5.7 mercruiser

[Scott Danforth]

Re: new boat, some questions on 5.7 mercruiser

sounds like the shift interrupt.

on your base timing. I would start at 6 degrees BTDC and keep trying it until you hit 10. somewhere you will find the optimum for your combination of parts.

 

[idleRelaxation]

Re: new boat, some questions on 5.7 mercruiser

sounds like the shift interrupt.

on your base timing. I would start at 6 degrees BTDC and keep trying it until you hit 10. somewhere you will find the optimum for your combination of parts.

even though it will shift into gear and idle in gear? so instead of interrupting at the engagement its interrupting after?

as i mentioned, i did adjust the shift cable assembly by moving the pin in the slot which i read only adjust the engagement of reverse, could that have affected the shift interruptor functioning in forward?

 

[tswiczko]

Re: new boat, some questions on 5.7 mercruiser

to be clear, i can put engage into forward and idle in forward gear, but if i try to increase throttle slightly (lets say for a no wake zone) itll bog down and turn off, but if i throttle up to say atleast above 1.5-2k rpms itll run perfectly fine
(8*)

Accelerator pump, or worn pump linkage.

 

[idleRelaxation]

Re: new boat, some questions on 5.7 mercruiser

Accelerator pump, or worn pump linkage.

i would normally agree, but it wasnt having this problem before i adjusted the base timing, which was previously very advanced, and i have no hesitation at all when reving motor not under load, which if i understand correctly, the accelerator pump function does not have to be tested while under load?

 

[John_S]

Re: new boat, some questions on 5.7 mercruiser

If when you had the advance out of spec, it was running high in rpms at idle, it would have masked the issue. Make sure the idle mixture, idle speed, and choke are all adjusted. If it is still doing it after that, time to diagnose, or adjust carb. What carb are you using, and is it relatively new?

 

[idleRelaxation]

Re: new boat, some questions on 5.7 mercruiser

If when you had the advance out of spec, it was running high in rpms at idle, it would have masked the issue. Make sure the idle mixture, idle speed, and choke are all adjusted. If it is still doing it after that, time to diagnose, or adjust carb. What carb are you using, and is it relatively new?

it was running at the same idle rpm as it is now,maybe 50 higher

the carb is an edelbrock 1410 and is rather new

 

[John_S]

Re: new boat, some questions on 5.7 mercruiser

it was running at the same idle rpm as it is now,maybe 50 higher

the carb is an edelbrock 1410 and is rather new

A 1410 from the factory is tuned to a larger engine (400ci). The smaller 1409 is tuned to a 350. After the above adjustments, you will probably have to tune the carb. The edelbrock manual is very good on how to go about it. The primary circuit is easy to change the rods, jets, and springs. The secondary jets require the top to come off to change jets. You might get away with just a primary adjustment, though. It also might be as simple as changing the accel pump position rod, to get you through the idle to primary transistion.

 

[idleRelaxation]

Re: new boat, some questions on 5.7 mercruiser

A 1410 from the factory is tuned to a larger engine (400ci). The smaller 1409 is tuned to a 350. After the above adjustments, you will probably have to tune the carb. The edelbrock manual is very good on how to go about it. The primary circuit is easy to change the rods, jets, and springs. The secondary jets require the top to come off to change jets. You might get away with just a primary adjustment, though. It also might be as simple as changing the accel pump position rod, to get you through the idle to primary transistion.

im going to check function of the accel pump/spring mechanism and get back to you

motor runs good all around except for that, so 1410 cant be too far off, wouldnt know if it had been tuned since previous owner had it installed

 

[John_S]

Re: new boat, some questions on 5.7 mercruiser

im going to check function of the accel pump/spring mechanism and get back to you

motor runs good all around except for that, so 1410 cant be too far off, wouldnt know if it had been tuned since previous owner had it installed

If it is only a problem when you accelerate, than I would lean toward the accel pump adjustment or problem. It sounded like you can't run steady at all near the 1K rpms. That is the transition zone from idle to primary circuit. Important to set idle mixture and idle rpm, and should be done repetively. Three times usually is enough, ..mixture, rpm, mixture, rpm, mixture, rpm. If it was way off, maybe another iteration. If it still an issue, then need to figure out if primary is too rich or too lean. Since it is a used carb, need ID the primary jets, rods, and springs.

 

[idleRelaxation]

Re: new boat, some questions on 5.7 mercruiser

If it is only a problem when you accelerate, than I would lean toward the accel pump adjustment or problem. It sounded like you can't run steady at all near the 1K rpms. That is the transition zone from idle to primary circuit. Important to set idle mixture and idle rpm, and should be done repetively. Three times usually is enough, ..mixture, rpm, mixture, rpm, mixture, rpm. If it was way off, maybe another iteration. If it still an issue, then need to figure out if primary is too rich or too lean. Since it is a used carb, need ID the primary jets, rods, and springs.

i will get back to you with all info on jets, rods and springs, and yes, if i try and run around 1k rpms (no wake zone) itll just bog down, rest of the time it runs perfect without a hitch

 

[idleRelaxation]

Re: new boat, some questions on 5.7 mercruiser

figured id check while in there if it makes sense, but since my compression was around 120-125 on all cylinders, good idea to do a valve adjustment? maybe too tight? cant find another reason for low compression all around with no other symptoms on motor

video i took this last week for a friend :
http://www.youtube.com/watch?v=qIzA4A8RQDw

exhaust is loud because boat is backed right up to a garage door, and if you look closely, the crocs made it into the video, though this time with no socks

 

[John_S]

Re: new boat, some questions on 5.7 mercruiser

figured id check while in there if it makes sense, but since my compression was around 120-125 on all cylinders, good idea to do a valve adjustment? maybe too tight? cant find another reason for low compression all around with no other symptoms on motor

video i took this last week for a friend :
http://www.youtube.com/watch?v=qIzA4A8RQDw

exhaust is loud because boat is backed right up to a garage door, and if you look closely, the crocs made it into the video, though this time with no socks

While that does seem low, I think the service manual just states that all cylinders should be within 10% of each other. Tested on a warm engine with throttle wide open? Have you tried a different gauge, or squirt oil into cylinders to see if compression rises? Adjusting the lifters, unless they were all over tightened, shouldn't be the issue. It is easy to do on a warm engine, but can be messy if you don't have clips or other means to catch the oil.

PS: Sounds like "big" cam idle to me.

 

[idleRelaxation]

Re: new boat, some questions on 5.7 mercruiser

While that does seem low, I think the service manual just states that all cylinders should be within 10% of each other. Tested on a warm engine with throttle wide open? Have you tried a different gauge, or squirt oil into cylinders to see if compression rises? Adjusting the lifters, unless they were all over tightened, shouldn't be the issue. It is easy to do on a warm engine, but can be messy if you don't have clips or other means to catch the oil.

PS: Sounds like "big" cam idle to me.

the motor was warm leaning towards cool, throttle was not wide open though :facepalm:

does sound like a big cam in video, person it is a little less, the video makes it seem more so because of the garage door, though i will admit it most likely is not stock, but i cant imagine someone swapping out the cam on a 95-00 roller cam block but then reinstalling non-vortec heads and then using a 1410 carb, seems the heads would be a tremendous bottle neck? i am going to get stamping off heads and take some pics this weekend if possible with valve covers off and also return with carb rods/spring info

it idles at 600rpms cleanly as you can see with timing at 8* btdc, which i will bump up to 9-10 soon

 

[mohead1]

Re: new boat, some questions on 5.7 mercruiser

Nice little Wellcraft, would love to have it......too much motor....watta yall talking about....that thing will be squirrely but will do 65 easy....fun machine, dont be skeerd....just use caution in rough water and in turns back er down a little till ya get it straight again.....drove many a hydroplane and small v with big motors.....youre good....just tune motor and hang on.....

 

[idleRelaxation]

Re: new boat, some questions on 5.7 mercruiser

Nice little Wellcraft, would love to have it......too much motor....watta yall talking about....that thing will be squirrely but will do 65 easy....fun machine, dont be skeerd....just use caution in rough water and in turns back er down a little till ya get it straight again.....drove many a hydroplane and small v with big motors.....youre good....just tune motor and hang on.....

haha! thanks!

the last time i took it out everything was working perfectly, the waters were a bit choppy for WOT runs but she did manage to get up to 58-59, I would imagine id get another 2-4mph on a smoother day. This is all with old style heads, not vortec, which I do see me upgrading in the near future, especially after realizing where the water entry into motor was occurring (exhaust mani gasket).

overall very fun boat, you do have to be careful but that generally with any boat, it did not have too poor of handling characteristics, even with no trim tabs.