Hello, I come here seeking help. This might be long, but I want to thoroughly explain what I have already done, to avoid rehashing the same things (as I have done myself for weeks now).
I have a 64 Deville that I received in non running condition. Old fuel had seized up some valves, and just about everything had to be taken apart, cleaned, and put back together.
The car only has 25,000 miles. Well, 25,300 as of today.
I've had a really tough time getting it to run properly. I had the heads cleaned up, a valve job performed, and hardened exhaust valve seats installed.
Compression is excellent and uniform across all cylinders, around 190.
I rebuilt the carburetor.
I disassembled and cleaned the fuel pump.
The fuel tank and sending unit have been replaced.
Obvious tuneup parts have been replaced with new.
First problem was that I was unable to get the idle down to 480RPMs in drive. All vacuum lines were disconnected and capped to perform testing. At first, I did have a leaking intake manifold gasket, I corrected that. There are NO vacuum leaks.
After that, I was able to get the idle down, but it didn't run particularly well. I adjusted the timing and dwell. The car falls all over itself when trying to accelerate, and stalls most times. No power.
I went and bought an Edelbrock 1411 750CFM carburetor, as I suspected trouble (and doubted my rebuild) on the original Rochester. I was able to get the car to kind of run with this carb, but only at idle. Before I installed it, I removed the intake manifold, drilled, tapped, and installed brass plugs into the exhaust ports beneath the carburetor so that I could run any carburetor. That's just a nasty idea anyway, but I digress.
I warmed the engine, and adjusted the mixture needles on the Edelbrock to get it dialed in, and began working toward lowering the idle to the specified 480 RPMs. It doesn't really run well down that low.
I managed to get to run long enough with the vacuum advance unhooked to get the timing set to 5 degrees BTDC, and set the dwell at 30 degrees as specified in the manual.
Back the car out of the garage- ok.. try to go, and it quits. Very frustrating.
So this morning, I thought, maybe the fuel pump isn't doing toowell. I don't have a gauge that goes low enough, so I just went and bought a cheesy electric fuel pump and some fresh hose, and hooked that up.
Fire it up, idles fine, kick down the idle when it warms up, fine, no problem. Try to go- and it quits.
So finally, I decided to start advancing the timing. Maybe this is the issue?
Now we're getting somewhere. It's now at least driveable. But something is just not right. It misses and spits and sputters under load, you have to feather the gas pedal to drive it. Once you're at speed, you can ease into it and drive it to 80MPH effortlessly... the engine is clearly good and strong. No noises, nothing- except random misfires and popping... not good at all :-(.
The advance mechanisms seem to be working. With the timing light, quickly 'blipping' the throttle causes the timing to retard as you'd expect with reduced vacuum to the vacuum advance.
Steadily increasing the speed of the engine results in the overall timing increasing.
As far as I know, all is correct here...
So what am I missing here? Why won't it run right, and why on earth should I have to advance the timing so much- that can't be right, nor can it be good for it long term.
I really want to drive this thing, hopefully someone can offer me some advice.
This is theory; Use an adjustable timing light. Unplug the vac advance and disable the mechanical advance with tape.
Set the timing light to zero deg and see what the timing is at. Then set the timing light to what the timing showed. With the engine running, the timing mark should be at zero. If it is off, you will know by how far.
It has 93 octane fuel in it. I even added a can of booster just because.
I used the Edelbrock 750 because it was for sale new in box locally for very cheap on craigslist. According to the Edelbrock website, it was a good fit for the engine, and I didn't want to mess around with changing jets and spend a bunch of time tuning. I hope to get the original carb running on the engine, as I assume it'd be proper. So the Edelbrock is really kind of an expensive troubleshooting tool.
I only modified the intake as far as blocking the exhaust passages underneath the carburetor.
I did not modify the intake beyond that, I used an aluminum spacer to deal with the interference of the throttle valve. It's not an ideal one either, as it's fully open rather than having four ports like the stock one.