Mercruiser Motor Timing

[mwilley22]

We have a 1988 Baja 265 w/ a 502 Motor that was completely redone and bored to a 509, boat has all stock ignition from 88 with distributor. When dropping the motor into the boat, does anyone know if the motor is self-timing or if it needs timed just as you do a car motor?

 

[Scott Danforth]

Re: Mercruiser Motor Timing

you will have to set the base timing.

 

[mwilley22]

Re: Mercruiser Motor Timing

Base timing as in on the Cam Shaft card or Comp Cam's recommendation like you would on a car/vehicle?

 

[Scott Danforth]

Re: Mercruiser Motor Timing

base timing on the distributor. not sure how your motor is set up, however my guess is about the range of 6-10 degrees advance at 650 RPM. your total advance will depend on the engine, the compression ratio, the cam timing, drive gear ratio, hull shape and weight, and prop. most distributors have an advance of 18-24 degrees with the majority being between 20 and 22 degrees.

so lets say your advance is 20 degrees, and your base timing is 10 degrees. you have total timing of 30 degrees.

the motor itself doesnt know its in a boat. it just knows its a motor. so if its installed in a truck, its a truck motor. if its installed in a boat its a boat motor, if its installed in a car its a car motor. the only caveat is that on a boat motor, all the stuff bolted to it must be marine certified.

 

[Don S]

Re: Mercruiser Motor Timing

No, it's not like a car. The 502 wasn't used by Mercruiser until 90, and you have an 88???

Do you have a Mercruiser serial number for that engine? Maybe some pictures? What ignitions system do you have? Carbed or EFI. and you thought it was going to be easy.

 

[mwilley22]

Re: Mercruiser Motor Timing

Using everything off of the stock 454 that was originally in the boat and using on the 502. And it is carbureted.

 

[Don S]

Re: Mercruiser Motor Timing

Here is a link to the manual that covers the ignition system for the 454. http://www.4shared.com/office/gXPsiAtn/09__GM_V8_All_85-88.html?

Section 1B has tuneup specs, section 4B covers the ignition system. Not sure what you want to set your 509 to.