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1994 7.4L Mercruiser - loss of top end

G

Gomesy

New member
Hello,
I have a 1994 7.4L Mercruiser. It was running fine last year but I had to get some maintenance done on it to repair some broken teeth on the flywheel. While doing this the mechanic replaced the belt because it was old and soon to fail. They also did some work on the gimbal.
When it went back into the water the timing was off. I was able to fix that myself but I don’t have the top end power I had before. It takes a much longer time to get to plane as well.
Could this be a belt issue?
There’s no squealing with the belt.
No interior engine work was done so it's the only thing I can think of that has changed from before.
Thanks in advance.
 
When it went back into the water the timing was off. I was able to fix that myself but I don’t have the top end power I had before. It takes a much longer time to get to plane as well.
Click to expand...
Have a motor serial number?

Being a 1994 it's most likely has a Carb and is not the 454 EFI

Timing at 8* and is it TB4 or TB5?
 
AllDodge said:
Have a motor serial number?

Being a 1994 it's most likely has a Carb and is not the 454 EFI

Timing at 8* and is it TB4 or TB5?
Click to expand...
It has a carb. When I use the timing light, I have the tdc line which has been highlighted in white and then another mark in red which I assume is the 8 degree line that a previous owner or mechanic has put on there. I don’t see a tachometer dial or guide to give me 8 degrees, just a pointer.

I was told it is a 5th Gen. Is that a TB5?
 
TB5 requires attaching the timing wire Pur/Wht to be attached to a good ground to set. Once timing is set the wire is removed

Timing is set at idle not anything above 700 rpm

Once timing is set and pur/wht is disconnected, rev the motor to see if timing is advancing
 
AllDodge said:
TB5 requires attaching the timing wire Pur/Wht to be attached to a good ground to set. Once timing is set the wire is removed

Timing is set at idle not anything above 700 rpm

Once timing is set and pur/wht is disconnected, rev the motor to see if timing is advancing
Click to expand...
Thanks. I’ll do that tomorrow.
 
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