AMC backfiring

Well its not a bad cyl. Compression was within 5psi...8 cyl were 105 and cylinders 4 and 8 were 110...
What else??

I dont have one darn it...

Forgive me if I am stating the obvious but you mentioned working on small block fords. Number one cylinder is on the opposite side than ford. http://www.cfsja.org/tech/drivetrain/firing/firing.html
Not trying to offend anyone by stating the obvious but it is impossible to really know what the persons skill or knowledge is through text on a screen.

Edit: Totally stating the obvious because Phat went into way more detail. Sorry.

Edited by Lucas660 - Jul/16/2018 at 6:29am

-that's a sure sign the distributor is 180 degrees off: pull it out and reinstall it with the rotor pointing the opposite direction, then try again.

-the next few possibilities are all solved with a Chilton's Repair Manual or an AMC Technical Service Manual (to get the engine running good again)

The $15 spent on a Chilton's Manual is well worth your time, compared to hours of guessing and wondering what might be wrong.

https://www.ebay.com/itm/Chiltons-Repair-Manual-1973-1980-Domestic-Cars-6850-AMC-Ford-Chevrolet-Dodge/272974728517?hash=item3f8e8fcd45%3Ag%3Aad4AAOSw0TxZaq7h&_sacat=0&_nkw=AMC+Chilton%27s+Repair+Manual&_from=R40&rt=nc&_trksid=m570.l1313


*** caution; backfiring through the carburetor is likely to cause a blown power valve in the carburetor.

Once you get the spark right, with the distributor re-oriented where it should be, you can double check the carburetor by taking it off, partially fill the float bowl with fuel, place it in a clean bucket, come back two hours later and see if there's a puddle of fuel in the bucket...

...if so, that would be fuel seeping down into the engine instead, which will dilute the engine oil with solvent, which is NOT good for the bearings (no matter who made the engine, Chevrolet, Ford or whatever) ...if so, replace the power valve & re-test the carb, same way (the power valve gasket must be tight or it can leak too after replacement; ethanol/gasohol is more tricky to work with than the 'old school' gasoline all these carbs were originally made to run with)

*another note: certainly I'm not the world's moral advisor ~but~ I've had one very bad experience with an engine fire and trust me, you don't want that to happen.

Get drunk and go dance with a female yes? but no; don't get drunk and work on the carburetor.

Please let someone who is mechanically inclined and sober to work on it instead.

An engine fire on a fiberglass boat could be your worst nightmare (fiberglass is flammable and the styrofoam filler -that's a bonfire waiting to happen/you don't wanna learn the hard way)

You should have a good fire extinguisher 'ready at hand' & ready to use at your workspace. (ounce of prevention is worth a pound of cure)


Edited by amcenthusiast - Jul/16/2018 at 10:39am

I would think maybe the rotor should be pointing a bit before #1 to allow for the advance but that can be changed if the distributor is in its travel range. Yes, wherever it is pointing you could use that for #1. I did it that way many years ago as a kid with a Ford Y block. I could have lifted the distributor to accomplish the same thing. 

Edited by vinny - Jul/17/2018 at 12:43pm