New motor ... setting timing

[Jason 641]

I just rebuilt the 260 mercruiser in my boat, it's an '85 chevy 350 w/ thunderbolt IV ignition. The only way to get it started and running long enough to check it with the timing light is to give it a good bit of throttle. The first time the timing was way off, so I turned the distributor to get it closer. that makes the engine rev way up (obviously) so every time I go to back off the throttle it will just stall. I need to get it to idle just long enough to time it quick then get the RPMs up so I don't mess up the new cam and so I can get the rings seated good.

Does anyone have any hints for me? or am I forgetting something? I only messed with it for about 10 minutes last night before it got dark.

 

[Don S]

Re: New motor ... setting timing

If you can keep it running around 2000 rpm, set the timing in the area of the red marks in the drawing below. That should get you in the ballpark for setting the timing.

 

[Jason 641]

Re: New motor ... setting timing

Cool, Thanks.

 

[Bt Doctur]

Re: New motor ... setting timing

Even so ,a brand new motor should be able to idle at startup if the static timing is close.Could you have a vac. leak at the carb base.

 

[Jason 641]

Re: New motor ... setting timing

Even so ,a brand new motor should be able to idle at startup if the static timing is close.Could you have a vac. leak at the carb base.

After the fact I realized that the reason it wouldn't stay running at idle was because the heat shield around the automatic choke was bent against the arm and wasn't allowing the choke to close. Don S method worked great though.

 

[J. Mark]

Re: New motor ... setting timing

I believe chokes are the cause of more problems than we will ever know. Glad you got it straight.

Nice diagram Don S. should help a lot of folks.