Runs terrible, backfires, no power

[Dster]

1969 2000 redo…going well until a couple of days ago. Started almost before I touched the key- really easy start! But I couldn’t keep it going without constant attention to the accelerator. It was running great at 2000 rpm, but as soon as I took my foot off, it would drop down to 600 rpm and die. Then I would have a hard time starting it until about an hour passed. I took it in to a mechanic for the first time thinking I would get it really tuned up for once. I had already put on a new coil, new points and condenser, new plugs and a rotor. The day before I was to take it in, I tried to put on a new distrib cap. Oops! Something I did caused it to run horribly, back fire like crazy etc. I fiddled with the wires and timing and got it to run good enough to barely make it to the mechanic. He put in a new fuel pump and said he did a bit of timing adjustment. Now I don’t have the prob of dying at low rpm but the backfiring is the same and power is about half normal at best. I’m thinking something is really screwed up with the timing and would love to have ideas!!

[david premo]

Reach out to Dave Witt he works on roadsters and he’s in the Sacramento area.

[Dster]

Thx how do I find him?

[david premo]

I’ll see if I can find his contact info.

[Gregs672000]

Remove the spark plugs and report what they look like. It's one of two things: Spark or fuel. I suspect spark based on what your saying and the fact that you were just in there. A timing light will tell you if the ignition is advancing or even firing. If you have a fuel problem it will show on the plugs.

No offense, but I'd question your choice in mechanics! These are basic engines/systems. Too many have come to rely on computers and swapping out parts.

[jrusso07]

Sounds like you may have misplaced the wires when you replaced the distributor cap?

[redroadster]

Could be a lot of things ; old gas , low flow gas , sp wires incorrect sequence,
Slow valves / old gas , weak spark spark gets weaker in compression , fuel fowled sp plugs , ign timing ,vacuum leaks , oil water in cyl.
I'd start with a complete cold compression test, note the 1st pump readings ,just so you know mechanicals are good , have a dwell meter?
Does it have a strong batt, cranking speed ? The intake valve is open on the compression stroke

Try a redundant ground neg power wire to the dist, sure a wire isn't arcing somewhere
Did you put 91 octane in recently , it's easy to get old 91 as if it's getting old setting in a tank they pump it out to sell cheap ,it's happened to me 2x and it has no power
Pull plugs crank it over ,blows gas out ? Chokes A ok?

[Dster]

The engine ran great before I fiddled with the distributor, so I’m thinking spark rather than fuel. I won’t go back to this mechanic!

[david premo]

Dster, it may be that he set the distributor to the factory TDC that without all of the other emissions equipment makes it run really bad. If the distributor is recurved then the initial advance would be 16 degrees before TDC. I ask the mechanic what he set it at and let him know how it has no power and runs really bad. Give him a chance to possibly fix it.
Dave

[Gregs672000]

"Return to the scene of the crime" is my suggestion if it went from fine to no Bueno. If desired, you can buy or borrow a few tools and likely figure this out yourself (and experience the feeling of success and learning). Like Dave said, it could be as easy as loosening a bolt and adjusting the timing... very easy with a timing light you can get at Harbor Freight type places for $20? Useful tool to have. It will tell you if your getting spark quite easily if ever needed. Understanding firing order, points etc are all helpful. Reading spark plugs can always help diagnose problems and how the engine is running. We'll help if you like!

[dynaguy]

Sounds like you may have misplaced the wires when you replaced the distributor cap?

Ditto. Pat

[Dster]

Here’s a photo of a new spark plug. Looks like a fuel problem, right? I can keep in running long enough to get it to a mechanic who knows these cars- all I have to do is set the idle at 1600. Interestingly, only one carburetor’s idle screw affects the idle speed. The other one has no effect. ??
Oops won’t let me add photo- the spark plug is black as charcoal …

[Stick]

Picture didn't go through, but if the plug is heavily fouled black it's definitely running rich.

I couldn't see where you reported back on the distributor wiring, plug wire connections and rotor position... have these been verified? Doesn't sound like that was the issue and you're now chasing fuel?

If so, I wouldn't take anything for granted at this point and I would verify the following:
1. Verify rotor position with TDC on the compression stroke
2. Check and set timing at idle and make sure it's advancing correctly under throttle
3 Verify exhaust and intake valve clearances are set correctly
4. Adjust the idle speed / carb balance.
5. "Read" the plugs for rich/lean condition at idle/cruise speeds
6. Adjust mixture if plugs show lean or rich at idle by rotating the mixture knob under the carbs (looking from the top of the carb and rotating counter-clockwise will lean out the idle mixture and vice versa).

I chased my tail on a lot of carb tuning prior to finding out my valve clearances were way off and timing wasn't quite right... things still ran ok, but once everything was set to spec it was like a new car. I also found out that my coil was bad and Arcing to ground due to a hairline fracture in the case.... caused troubles restarting after hot

[Stick]

I just read through some of your older posts and it looks like you were having the same issues back in April when you removed the tach cable from the distributor. viewtopic.php?p=347403#p347403

as well as an issue with the coil?
viewtopic.php?p=347414#p347414

Sound like both times it was running and then not running and backfiring after fiddling with the ignition system... I'm guessing that the root of your troubles will be found in the distributor/coil. If it's not getting a strong spark for all cylinders at the right timing it can still foul the plugs.

[Dster]

Thanks for all the ideas! I talked with Dave Witt and he helped me figure out that one of my choke cables was stuck and as soon as I released it, the result was hugely better. Now I can at least drive it! It’s still not great, so I’ll start back at the beginning as Greg and others have suggested. Let the fun begin!!