1977 140 Merc I/O timing problem

DRFleck

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Oct 2, 2012
Messages
1
I have a 1977 24 foot FiberForm with twin 140 Mercruiser I/O's. The problem is one is starting and the other is not. It appeared to be seized but after much effort, I got it cranking again. When I was working on it, I pulled the distributor. Now when I turn it over, it backfires up through the carb. I brought the timing mark on the crank pulley (it was never removed) around to the tab on both motors. The rotors on both distributors are pointing in the exact same direction. Both motors have been converted to electronic ignition. I can't help but thinking I didn't install the distributor correctly, but everything seems to be in the right place. I'm stumped. Any help at all would be awesome, Thanks
 

Bondo

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Joined
Apr 17, 2002
Messages
70,468
Re: 1977 140 Merc I/O timing problem

I have a 1977 24 foot FiberForm with twin 140 Mercruiser I/O's. The problem is one is starting and the other is not. It appeared to be seized but after much effort, I got it cranking again. When I was working on it, I pulled the distributor. Now when I turn it over, it backfires up through the carb. I brought the timing mark on the crank pulley (it was never removed) around to the tab on both motors. The rotors on both distributors are pointing in the exact same direction. Both motors have been converted to electronic ignition. I can't help but thinking I didn't install the distributor correctly, but everything seems to be in the right place. I'm stumped. Any help at all would be awesome, Thanks

Ayuh,.... Welcome Aboard,... My guess is, you've got the distributer 180? out....

The crankshaft timin' mark comes up Twice, each time the distributer goes 'round once...

You stabbed the distributer on the timin' mark, on the wrong rotation..

What kinda great effort did ya do,..?? the backstory always helps...
 

Don S

Honorary Moderator Emeritus
Joined
Aug 31, 2004
Messages
62,321
Re: 1977 140 Merc I/O timing problem

It appeared to be seized but after much effort, I got it cranking again.

Do a compression test and see if you are working on anything to start with.

If you have usable compression, you need to make sure you are on #1 TDC On the compression stroke. Don't forget, the crank turns twice to the cam and distributors one time. You start out on the wrong stroke and eveything, timeing, valve adjustment, distributor installation is all going to be wrong.

Here is how you find #1TDC on the compression stroke. http://forums.iboats.com/showthread.php?t=427081
 
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