72 Mustang Running Rough

Sean,
If you have a timing light, get it hooked up and see if the mechanical advance is working. If you don't have one, take a look under the point plate and see if it's rusted up .

Cool Atom. We had a 60 hp Atom growing up. Crazy that it could easily pull skiers with such a high HP to weight ratio.

Quick update. I had a starter issue and could not revive the original. I ordered a rebuilt one and it will be here tomorrow so I can dig into the timing a bit. I just assumed the timing was set as the boat had been sitting for 25 years. I hope that this is the main problem. I kept the original starter and will rebuild it in the off season if I can get the boat running. I am considering HEI for easier maintenance. Let me get it running first and then I will give it a little more thought.

Ok. The new starter works really well and the engine fires up but will still only idles at about 1200 rpm. The dwell and timing seems okay, but I cannot rev the engine to check the advance timing because the mechanical secondaries on the carburetor are not pumping any fuel. Ignition module? Or screwed up carburetor? Any help is appreciated.

Update. The secondary throttle plates do not open at all, even when the throttle is fully engaged. From what I read, both sets of throttle plates should open with the throttle. The secondary intake is not going to ever open because the throttle plate isn't open. I cannot find any adjustment on the carburetor that will release the lock for the secondary throttle plates based on throttle position. Any ideas?

Here is the carburetor. I made a little more progress today. I started the motor and then held the choke open while I pushed the throttle all the way forward. This released the secondary throttle plate lever which I have shown in the picture.    The engine slowly crept up to 4000 rpm. A fair amount of smoke and some misfires, but better than 2000 rpm. I am going to look at the vacuum linkage pictures to see why the choke isn't actuating. The secondary throttle plates won't open unless the vacuum linkage releases the stop lever I have shown. Talked to a mopar guy and we are going to pressure the cylinders and verify compression. Small steps.    

Had about a 10 minute run today at 3000 rpm which is getting better. Still running rough. I sprayed a can of Sea Foam down the carburetor and am hoping that this might cook some of the carbon / rust off the valves / pistons. I'm beginning to think the carburetor is working but might have a low compression issue. I am going to pressure test the pistons. As a side note this has a Chrysler 273 in it, which have been practically the last Marine 200 installed in a boat as they went to the 318. Does anyone have the timing info for a Marine 200?

onebigdog wrote: I think I am in business. I can't find a way to set the timing exactly but it seems to be running a lot better. https://youtu.be/J6vuxQYiyCQ Thanks for your help!

Sean,
Great to hear that it's running better and per your video, you are making progress. Now as you mentioned, the next step will be on the lake.

Tell us about the issue you are having with setting the timing. I know we can help.


Also, here's a direct link to your video.

Does anyone know how much a new Mustang would have cost in 1972?