timing mark is missing guide all together

[legoman67]

1979 mercruiser 255mie

The timing mark is missing the guide on the block by about 1/2" retarded. When i turn the dizzy it moves but the engine cuts before i can get it within range. I dont get any backfiring out of the carb, and the engine actually runs quite well besides an occasional pop out the exhaust, and a slight surging(<100rpm)

Any ideas? Ive triple checked the firing order and its correct. I made sure the timing gun was connected to cylinder 1, and i tried at a range of rpm(650-1200) It shows about the same for all.

 

[Don S]

Re: timing mark is missing guide all together

Raise the rpm a bit, adjust the timing, then readjust the MIXTURE, then adjust the idle rpm. Recheck the timing till you get it right.

Note: if you have points type distributor, make sure you have the dwell set properly first, then set the timing.

 

[legoman67]

Re: timing mark is missing guide all together

raise the rpm higher then 1200? What rpm would you suggest?

 

[Don S]

Re: timing mark is missing guide all together

High enough it doesn't die when you move it a few degrees. If your engine won't run with the timing out only 1/2 inch (6 or 8 degrees), then you may have other things wrong. What are you idling at now?

 

[legoman67]

Re: timing mark is missing guide all together

it likes to idle about ~700, i can rotate the distributor probably a good 30* and the engine will stay running, but 30* isn't enough to bring the mark up to where it needs to be.

Also, it sounds like its running best when the distributor is in the middle of its rotation range(most constant and slightly higher rpm sound), and sounds worse on either extreme.

also, i should mention that i threw this distributor on the engine over the winter because the old one was having issues of its own. I made a reference of rotor direction as i pulled the old out and used that to set the new one in, is it possible i have it a tooth off? would that show the symptoms i am having?

 

[mkast]

Re: timing mark is missing guide all together

also, i should mention that i threw this distributor on the engine over the winter because the old one was having issues of its own. I made a reference of rotor direction as i pulled the old out and used that to set the new one in, is it possible i have it a tooth off? would that show the symptoms i am having?

Turn the engine over to Top Dead Center on the compression stroke of the number one cylinder.
Remove the distributor cap, look at the position of the rotor, should be pointing at the number one spark plug wire on the distributor cap.

 

[saywhat]

Re: timing mark is missing guide all together

If you removed the entire distributor from the engine block without taking a picture of the rotor position - or if the crank was moved with the dizzy out - it is possible it could be off a tooth.

I would second what mkast said just to be sure the distributor matches TDC on cylinder 1.....

 

[Black as]

Re: timing mark is missing guide all together

You also need to check your springs and fly weights under your points plate, if they are sticking you will have problems setting your timing.