1988 Mercruiser 5.7 timing issue.

[dbohnett]

Sorry for the delay. My main driver vehicle has issues and have been working on them so this went to the back burner. Will check the latest suggestions and post my findings ASAP. Thanks

 

[tank1949]

This is a different engine. Removed the 305 and installed a totally complete 350. I did not remove the distributor, only tried to adjust the timing. Also, this is a sterndrive. Thanks

Automotive or marine motor with marine dist?

 

[cdavy000]

Just installed this engine. Coil, cap, rotor, plugs, wires all replaced. All plug wires connected to correct cylinders. Did not move the distributor. Starts OK, idles a little rough. Checked the timing and it is set to about 33 degrees {approx} BTDC at 750 RPM, warm engine. Try to rotate dist. to achieve 8 degrees and engine runs terrible and backfires. Any ideas?

Is it backfiring out of the carberator or exhaust. Since it happens when you try to retard the timing I’m gonna assume it’s exhaust which would mean it’s running rich, try to reset your idle fuel mixture back to factory settings. Setting the engine rpm at such an advanced timing mark is gonna force you to set the idle speed a lot lower to compensate as the higher advance is gonna increase your rpm’s. Does the engine slow down a lot and chug hard like it wants to die when you try to set timing to 8 btdc? That’s because retarding timing is decreasing idle speed below the required idle rpm of 750. Just increase the idle speed as you retard the timing to compensate.

 

[dbohnett]

Thanks for the responses... This is a marine engine. Engine does slow down and want to cut out, will also exhaust backfire intermittently. Will also emit some steam when hot and at higher rpms. Overheating because of the poor timing probably? Will give your suggestion a go.

 

[ROY WILLIAMS]

The engine rpm 650-700 RPM , adjustment is 8 degrees BTDC, Mercruiser ... Now reset the idle to 725 and recheck the CARB mix. Repeat til it is adjusted to correct mix and low idle at 8 degrees and with 140 degree thermostat, engine warm.

 

[cdavy000]

Thanks for the responses... This is a marine engine. Engine does slow down and want to cut out, will also exhaust backfire intermittently. Will also emit some steam when hot and at higher rpms. Overheating because of the poor timing probably? Will give your suggestion a go.

It definitely sounds like you are running rich. So if resetting your timing doesn’t fix it you need to look into your air to fuel mixture and determine why it is getting too little air or too much fuel. But I’m confident resetting timing will fix it, if it is wrong.