440 wants to idle at 35-40° btdc?
 

I just picked up a project truck with a 440 from a 1978 New Yorker. From what I have been told it's got about 5k miles, on a .20 over rebuild approx 9.5-1 compression and a mild "RV" cam, Edlebrock 750 with electronic ignition. It wasn't running the best when I got it and after cleaning up the carb it's a lot better but I'm getting readings on a timing light of around 36° at approx 850rpm (yes vacuum advance is unhooked) I've checked the balancer against TDC on cylinder #1 and the line on the balancer lines up with the little hole in the timing tab and rotor is pointing to just before #1 plug wire. It dies when I try to retard it . This thing can't really want to run at 35+ degrees of initial timing can it? What an I missing here? I'm new to Dodges but I thought timing was timing.

Something is off, check and see if #1 is infact #1.

It is, I double checked and numbered them.

It has a Mopar "orange" ignition box, any chance this like an MSD multispark box where you have to disconnect something to get accurate readings on a timing light?

Using the distributor to verify top dead center isn't accurate. You need to pull the plug in number 1 and find and find tdc in that hole. On a big block mopar that's the front cylinder on the drivers side.

I found TDC with the rag in the spark plug hole trick. I know that isn't the most accurate method, but unfortunately the header tube runs above the plug hole, effectively blocking it from any sticks or line of sight. After the rag popped the line on the balancer was aligned with the hole in the indicator ( which I believe is 0° ) and the rotor was just before cylinder #1 on the cap.

How much advance do you have at 3500 rpm?

I don't recall exactly but I think it was in the 50's. I'll try to check again probably this weekend when it warms up a little and I can have the garage door open and not freeze or gas myself out.

Zen -

One of two things.
The plug wires are shifted over one tower. (Yeah, I know you checked.)
The timing chain slipped or was installed incorrectly.

Archer

Don't rely on the distributor position, buy or build a piston stop to do an accurate TDC location.

and I would say add a little more timing and see how it runs. If it runs good by ear, and you have no detonation with decent vacuum, let it idle. I have a small block .030 over with a cam, headers and DUI distributor and it likes it there too. It runs fine. maybe the cam was off a tooth or maybe the harmonic balancer is not marked just right. If it isn't detonating, and the engine runs good by ear and starts fine, call it good.

*UPDATE*
After speaking with the previous owner I learned that the gas is probably a year old and possibly 87 octane ( 10% ethanol :doh: ) After draining the tank and giving it a fresh gulp of 91 it not only runs like a new machine, it will happily let me turn the timing down to 18° @ 750rpm! I thought bad gas wanted retarded timing? I still have a little tweaking to do but there is hope in sight. I also learned that it's near impossible to do a W.O.T. test on 440 in an empty 1/2 ton pickup truck :devil:
Is 18°@750 (with no vac advance) a good starting place, or should I be more concerned about total timing at a higher (?) RPM?

Total mechanical advance should be less than 38 degrees.