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Mercruiser 120 specs 1964- 72 Gm

FishingTheFL

FishingTheFL
in This Old Boat

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Shellback

Shellback

Posted
Posted

So he has the plugs right in picture I posted.

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Your picture in post #34 shows the firing order is correct. But as rolmps stated, your #1 position has to relate to where the rotor is pointing when the engine is at top dead center on the compression stroke. If you bring the engine to TDC and the rotor is not pointing at #1, you can move #1 wire to the position the rotor is pointing, then plug in #3, #4, and #2 following #1 in a clockwise direction. 

Shellback

Shellback

Posted
Posted

In an earlier post, you listed the point gap at .022. Set the points at that, and don't worry about the dwell. That 4 cyl, point ignition, carb motor is about as basic as you can get. Engine TDC on compression stroke, rotor pointing at #1 wire, firing order correct, and it's getting gas, you should only have to adjust the distributor timing a little as it cranks, then it should run if the cam and lifters were installed properly. Once started and running, set the timing with a light.

FishingTheFL

FishingTheFL

Posted
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Posted

Let's say he had everything with the timing right. Black ash like material was coming out of the exhaust and floating on the surface. I'm going to put it back the way he had everything and put muffs on it see if its still doing it. Could it be the carb messed up? He said it seemed like it was getting to much fuel. If I remember right he adjusted the carb but it made no difference

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Shellback

Shellback

Posted
Posted

Yes the carb could be messed up. Did he have it off when he did the cam job? If it was upside down or sideways, it could have effected the float. I don't see a reason to have the carb off doing the cam though, and think it's unlikely to be your problem, but you can't rule it out. Personally if everything was right with the distributor timing and firing order, I'd start thinking about valve adjustment. Could some be set too tight? That will cause a problem for sure. 

Shellback

Shellback

Posted
Posted

67374456f0f313f8cf6c4ecfec18fb6f.jpg

df326838296c314edf4b3aa0d2f5653a.jpg

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At tdc

Also the rods can still be twisted. Thought they were suppose to be tightened till they couldn't twist any more and then add 3/4 turn?

Are you speaking about the pushrods for the valves? I've always adjusted them with the engine running. Back off the nut till they start clacking, then tighten till they stop and add a 1/2 turn or so. The pushrods should still rotate when adjusted properly.

stoneam2006

stoneam2006

Posted
Posted

So I just started it up... Turned the distributor ccw around 45*... Now it runs beautifully... Idk what the deal is... Didn't touch the lash just took the cover off... Fired it up... Turned distributor... Bam...she runs. Gave her gas right up to 40k.

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Awesome I am glad to hear that

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L&M

L&M

Posted
Posted

So I just started it up... Turned the distributor ccw around 45*... Now it runs beautifully... Idk what the deal is... Didn't touch the lash just took the cover off... Fired it up... Turned distributor... Bam...she runs. Gave her gas right up to 40k.

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Nice to see you got it running, but you'll be replacing more than a cam if you keep running that up to 4k with no load on it . Just sayin ;)

rolmops

rolmops

Posted
Posted

Now after a few tries to make sure it was good... Won't fire... Improperly gapped maybe? Would switching this to electronic ignition get rid of the issue... Seems this could be simply but not really lol

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Check for a loose wire

Xxx

Xxx

Posted
Posted

When you go to time it make sure your rpm's stay below 650, if when timing it if it starts to gain rpm's keep backing the idle screw out to bring the rpm's below 650. You do this to keep the mechanical advance out of the scene, time her up to specs and lock the distributor down. The mechanical advance works with the rpm's of motor. If you did the timing say at 800 rpm the mechanical advance would be advancing the timing already then you would be off, say retarded at the whole rpm range because it already had advanced it's self. Sound like you got'er licked. Now you got a hell of an education, one you won't forget!!! LOL

FishingTheFL

FishingTheFL

Posted
  • Author
Posted (edited)

I forgot to lock the distributor down... I'm going to repeat everything I did today. The rpms where closer to 1000 when I get it running. Take it to reduce the rpms I gotta mess with the carb?

I'm definitely getting a crash course on mechanics. Now I just need to buy the tools lol. Got a timing gun last night.

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Edited by FishingTheFL
rolmops

rolmops

Posted
Posted

Just out of curiosity, do you have the muffs on when you do these tests?

Xxx

Xxx

Posted
Posted

Yes

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X2 !! I have a wrench that's bent like off set right then strait for about a foot or more then offset left if I remember right there 9/16 box end. It helps having a whole snap-on box given to you from my father who's of 30 + years being a mechanic,

Xxx

Xxx

Posted
Posted

Great to hear it's running, but not good on the knock. Don't forget that washer/shim isn't in there, maybe your sound could be coming from that? Or is the sound more deep and lower. Like a wrist pin or a bad bearing,, I'm pulling for ya bud!!!

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