Mercruiser 4.3l timing specs

[kloobs2305]

I have a 1988 SeaRay 270DA with twin 4.3l 175hp Mercruiser engines and Alpha one drives.

My engines were stalling as I shifted into neutral during docking maneuvers. At first I thought the engine was at fault and had it tuned up. My 1988 4.3l 175hp Mercruiser timing was set at 0deg BTDC but a mechanic recently changed it to 8deg BTDC. Now it seems that the engine is not able to get to full RPM's and takes much longer to plane. I am concerned that the new timing is wrong. Any comments would be appreciated.

Regarding the shifting problems mentioned above, they continued after the tuneup and we replaced one shift interrupter switch. Unfortunately Mercruiser obsoleted the old one and the replacement has shown no improvement.

Reading in this forum, I think we will have to go the Alpha one shift cable next.

Any comments on the shift problem would also be appreciated.

 

[Don S]

Re: Mercruiser 4.3l timing specs

The timing should be 8? BTDC, but did he check to make sure the advance was working. If it's not working, you will have problems with WOT rpms.

And yes, the shift cable is probably your problem. The shift interrupt switches seldom fail like that, but the shift cable is a common problem. Just pull the drive, disconnect the cable and feel the movement. Should be very, very smooth with no binding.

 

[kloobs2305]

Re: Mercruiser 4.3l timing specs

Not sure that he checked on the advance. Is this an electronic or mechanical advance on a 1988 Mercruiser? If the advance is not working, perhaps it is the reason that the old setting was set at 0deg????? However, it doesn't seem that is a good thing to do.

Comments?

Thanks

 

[Don S]

Re: Mercruiser 4.3l timing specs

It's an electronic advance, just run the engine in neutral with a timing light hooked up and see if the timing mark advances about 20 more degrees when revved to about 3000 rpm.