Messed up firing order? I need help!

[pehlen]

So like an idiot, I replaced the distributor cap, plugs and plug wires on my 66 convertible without documenting them first. I have the shop manual--I assumed it could be nothing else. Now I can't get it started.

I've tried 15426378 and 13726548 but neither works (although the latter sounds better). The engine was replaced in 88, but it looks stock, at least it seems to be stock, it's painted blue, etc. The origininal intake manifold is on it and it has the firing order printed on it but I'm thinking that a different cam must have been used in the rebuilt engine. I've verified that there's spark at the coil and to the plug wires and there's gas in the carb.

I initially replaced all this crap because I was getting backfires and stalls at idle which had never happened before. I had replaced the fuel pump a few months ago and haven't put many miles on it since then, but it ran great after I did that so I don't think that's related but who knows? If it's caused by the fuel pump is there any way I can test that without just going ahead and replacing the fuel pump again?

Can anyone help with a suggestion of another logical choice for a firing order or another idea why I can't get it going?

TIA

[PKRWUD]

Those are the correct firing orders. It has to be one of them. The backfiring, if through the intake, is probably due to a blown power valve in the carb. If the engine has an HO cam in it, then you need the 1-3-7-2-6-5-4-8 firing order. If it was built to stock specs, with a non-HO cam, than it has the 1-5-4-2-6-3-7-8 firing order. Make sure that the spark plug wires are completely seperated from each other, from the distributor cap all the way to the spark plugs. Then, set the engine to TDC on the compression stroke, and make sure the rotor is pointing to the #1 wire. This should enable it to start. With the vacuum advance disconnected and plugged, start the engine and adjust the timing to 10 degrees BTDC. Next, set the idle speed, and adjust the idle mixture. If the carb is good, this should work fine.

BTW, the easiest way to verify the piston is at TDC on the compression stroke is to remove the spark plug, and stick a wadded up piece of paper towel into the spark plug hole. Rotate the engine by hand until the towel pops out, and then go to the TDC mark (should be close).

Take care,
-Chris

[pehlen]

I'll try it this weekend. Do you think there's any chance this is related to the replaced fuel pump if gas is getting to the carb?

Peter

[PKRWUD]

You said it ran fine after changing the pump, so I doubt it. What kind of pump did you install? Have you checked the fuel pressure at the carb?

[1969Mach1]

Make sure your distributor cap is the correct one, and isn't broken. My dad and I replaced the one on the Vette last summer and it kept backfiring we couldn't figure out what was wrong. We forgot the order but we were able to locate the correct one on the net. But it still was back firing. I was playing around with it and was checking it out and there was a peice on the bottom that wasn't allowing a full connection, which was causing that. Try putting your old one on and see if it works in that order if it does then it's your cap. I just hope you kept your old one.

§am.