piperman60

Hello all and happy new year, I was wanting some advice if possible please, I have some issues with the 371 motor such as when i drive the car the generator light stays on and also i get some backfires through the carby? I have relaced all of the spark plugs as well as the leads and have had the carby rebuilt, I also had the generator tested and it was fine, I have also set the timing to the specs the 58 olds workshop manual says. Also when i touch the positive and negative terminals on the coil with a test light from the battery the test light lights up on both with the key off , is this normal? The motor seems to run slightly better when it is cooler but as it warms up it seems to run worse? do you think maybe its a head gasket issue? the motor has 98000 miles on it. Cheers , Ray, Brisbane Australia.

FMB42

And a good New Year to you as well.

I'd start by checking the following:

1. Intake manifold/vacuum leaks.

2. Ign. timing. Keep in mind that the crankshaft harmonic balancer/dampener may have 'slipped' due to a failure of the rubber section, if equipped (this can, of course, cause an improper timing adjment).

3. Distributor and/or dist timing advance problems (worn dist shaft bushing2, stuck advance weights, etc)

4. Carb accelerator pump.

5. Improper carb idle mixture adjustment and/or float level setting.

6. Internal carb problems.

7. Sticking and/or miss-adjusted valves. A vacuum gauge can be a very useful tool for checking this and other related problems (i.e. low manifold vacuum, etc).

redoldsman

If you have a vacuum gauge, try adjusting your timing until you get the highest vacuum. A vacuum gauge will also help you diagnose possible vacuum leaks. At idle, you should run at least 15 inches of vacuum depending on engine condition.

piperman60

Thanks very much for your input, i will start to check these suggestions out and see what we can come up with , I'll keep you posted , Ray.

lazy394

Is it a generator or alternator?
The new old style Alternators look just like a Generator but have an in built regulator so if the old set up is left in place it keeps the Gen light on all the time even though its charging. From memory gens have 2 wires and the Alt has a single wire.
As for the off running if you have just started to use a car that's been sitting chances are all the crud from the tank is now mobile and the carbs full of it, again. Take the top off the carb and have a look and think about fitting a see through fuel filter and keeping an eye on it.


Scott

D. Yaros

A '58 Olds would never have had an alternator from the factory. If it has one, it was added by someone at a later date. I believe the first year for an alternator on an Olds was '62 or '63?

Tedd Thompson

The backfire through the carburetor could very well be a bad valve. I've had that happen on several of my old beater cars in the past. You might as well run a compression test and eliminate that from the list ...Tedd

Ozzie

A bit more checking is in order.
As Tedd said, probably a compression test would help. This will tell you the general health of the engine and may reveal a specific problem with one cylinder. Use the kind of tester which screws into the spark plug hole. Remove the spark plugs; be sure the choke and throttle are open. Notice how many compression strokes are required to maximize the values. Record the values you get. This will tell you if there is a head gasket, piston/rings or valve problem.
When the generator is stopped with the ignition switch "on" the red light should be on. As the generator speed increases it will increase the output voltage if it is working correctly. When the generator's voltage surpasses the voltage of the battery, the regulator's cutout relay points should close (connecting the generator) and allowing it to charge the battery. At this point the red light should go out. If it doesn't the first thing to check is the regulator's cutout relay. It is adjustable. Another possibility is bad connections in the wiring.
The ignition coil terminals should not have voltage to them when the ignition switch is in the "off" position. Somehow you are getting voltage to the primary side of the coil. It could be a switch problem or some wiring problem. Look at the wiring diagram on page 13-2 of your shop manual and try to figure out where the errant voltage is coming from.
The backfiring through the carburetor could be caused by more than one thing. It could be a valve problem. The compression test should show this. It could be a spark coming to one cylinder at the wrong time. Check that there is no crossfire between the spark plug wires. Observing the engine while running in complete darkness can sometime reveal this situation. Also check that all wires are connected to the correct cylinder and the correct distributor cap terminal.
Running worse when hot is a clue. If a head gasket is blown it may leak more when hot. If a valve is sticking, it may move less when hot. If there is a warp or crack, heat may aggravate the situation. Check the operating temperature of the engine when hot. Overheated engines usually do worse than ones which operate at "normal" temperatures. Those engines used either a 160F or 180F thermostat (depending on the type of anti-freeze) on the Fahrenheit scale . In Celsius it would be 71C or 82C (if I did the conversion correctly).
All my comments are based on a "stock" setup. If non-stock conditions are present check them in detail.
Best wishes.

64Rocket

to me the volt regulator is why the light stays on.


Gene

lazy394

It would not be original fitment , I had and experience where a new Generator was installed but was in fact an Alternator. Because the original set up has an external regulator it will keep the gen light on and did odd things with the ignition.
The attached pic is an alternator.


Scott

piperman60

Thanks very much for your reply, Im going to get a compression tester in the morning and start to go through the list ,Thanks again!!

piperman60

Hello again, I just wanted to run this idea past you guys to see what you think? When i first set the timing on the olds i set it to 5degs bfore tdc as it said in the book but it was still running rough as,, Yesterday i turned the dizzy clockwise maybe an inch and now the motor runs a lot smoother but when i put the timing light on it there are no timing slots to be seen anywhere on the balancer, Does anyone think maybe the dizzy could be one or two teeth out? Also now when i try to start the car its as though the battery is low , but the engine starts but takes a lot to turn it over, Any thoughts please**, Cheers , Ray.

Ozzie

If the battery & starter are having new difficulty spinning the engine, it sounds like the timing is advanced too far. Don't overload the starter motor on a regular basis. That might create an additional problem. Recheck the placement of the spark plug wires in the distributor and check to see that the harmonic balancer has not lost its bond causing the ring to slip. Changing the tooth position of the distributor's drive gear would affect the (rotational) position of the distributor in the engine, but shouldn't affect the way it runs (with the timing set the same). After you do the compression test, you will better know the basic health of the engine. The ignition timing situation may be getting confounded due to a separate problem.

D. Yaros

I read indications that the timing mark ring on the harmonic balancer is no longer reading correctly due to slippage.