I recently sold my 1964 Ford Falcon and have been looking for a classic car ever since. I came upon a 1970 Nova- It’s a 3 speed with a 350 cu in V-8 motor. It needs a good bit of TLC but I like it. I test drove it yesterday and I could tell the motor was not performing well- it felt like something was holding back the power. The owner said the carburetor was messed up and needed some work. After about driving for 3 minutes the car back-fired very loudly and stalled out- It may have stalled and then backfired- I’m not sure- it all happened pretty quick. We were unable to get it to turn over and thought it flooded- so we waited and then it seemed like the battery was getting weaker. He said it was a new battery and thought it hadn’t run long enough for the alternator to charge it up good. I thought if it is a new battery and just trying to re-start it half a dozen times kills it then something else is wrong with the charging system. My guess is the alternator or some part of it is not working properly. Also- will a bad carburetor make it run poorly and cause it to backfire? That does make sense to me but I am a little concerned about the inability to restart the vehicle.
I’m thinking it’s more ignition-related. Or it could be the timing chain is really worn and has jumped a tooth. Also, I’d check the compression before buying, I’d want to know if an engine rebuild was in the immediate future.
Count my vote as one for running a compression check and the problem possibly being related to the ignition system.
Any carburetion or ignition fault will be simple and relatively inexpensive to fix so make sure you’re getting an engine worth fixing.
The engine was “professionally rebuilt” in 2004 and has very little mileage on it. It’s kind of hard to do a compression check if the car won’t turn over-LOL! I will ask the owner to get that done and have his mechanic fax his findings to me.
If the battery, new or not, wasn’t fully charged (which can take several hours to do) trying to re-start it half a dozen times can bring it down.
A few short trips won’t thoroughly charge a non-full battery.
A new battery loses charge sitting on the shelf. Maybe 10% a month.
Once you get it running again a voltage check will reveal the condition of the alternator.
I would expect 13.5-14V with the engine idling and all accessories off.
Are we talking about the stock points ignition?? That’s the FIRST place to look…Today, very few hobby mechanics (or professional mechanics) know how to properly set up an old GM points ignition.
Step one: Pull the coil wire out of the distributor, hold it near any metal surface, crank the engine and check for spark…You should see a nice steady repeating spark jump off the end of the coil wire…
I’d ask the seller to get somebody who knows what they’re doing to get this running right - a 2004 rebuild should run fine, and I imagine seller’s asking $$ for it.
Certainly a carb problem can cause a backfire. But so can ignition problems. It could be badly out of time, someone could have messed up the firing order by not putting the correct plug wire on the correct plug.
I agree texases that a “rebuilt” motor circa 2004 should be running pretty good. It sounds like the seller isn’t very car savey which seems odd for an owner of a “classic” car. Something fishy here, and I’d have a very good mechanic check this all out before parting with any money.
The last I heard from him he said that the gas in the car was bad and that he is taking the carburetor to a certified mechanic to look at- he thinks this will fix the problem- I told him I don’t want to purchase the vehicle until the motor is running smoothly again. It turns out the vehicle has not been driven much for close to 3 years which makes me think they need to check the entire fuel system and clean everything.
If that’s 3 year old gasoline in there then that’s likely where the problem is.
However, I would still run a compression test and start with connecting a vacuum gauge to it. The vac. gauge is easy, fast, and it will tell you in a heartbeat if there’s a problem with that motor and whether you should even proceed with a compression test.
It’s a big investment and you should never, ever accept anyone’s word about an engine or transmission rebuild because the word rebuild can mean many things. Many of those things are not good.
If they can produce a stack of receipts showing all parts used, machine work involved, etc then you can at least put a little credence into it.