RXN

I'm having some issues I'm wondering if anyone encountered them before or may be able to point me in the right direction.

This is on my 1958 Olds 88, 371.



The old girl was running fine, into town, on the way home as soon as you took your foot off the gas it ran rough, would sputter and stall out. First thoughts was carb, So I put in a carb kit.
The float is set as per spec, 1.375" level with a 1.906" drop. Carb rebuilt. I replaced the fuel pump / vacuum booster today as well. and again when idling it wants to stall. It may run maybe 5 mins nicely then it'll sputter and die.

Gone online a few times to check for solutions.
Here is what we did:
- Blew air from the fuel pump in line back to the tank. Could hear air in the tank.
- Compression test, most at 135, one at 140 and one at 150.
- Replaced all vacuum lines coming off carb. (found one cracked hose). I can pump up to 15" vacuum with the hand pump, and it slowly leaks out. When car running I get 20" vacuum steady.
- The distributor looks good, cap, rotor and points were changed in May of 2013. Still look new. Vac advance working nicely. Dwell set at 28 degrees
- Plugs didn't look too bad.
- Installed a carb kit, cleaned out the carb, its in good shape, no gunk or plugage.
- I had the timing light on it, and noticed when it sputtered that the light was randomly flashing {like a miss???}
- Could not locate timing marks. when we turned the crank by hand and saw the timing marks, I went to wipe them clean, and learnt that the vibration dampner has fallen off the hub.

I need to get a bigger 3 jaw puller to pop that off, and I'll change the front seal, possibly the timing chain.

Any idea what could be causing the sputter and dying? I'm pulling my hair out on this one.
Thanks

- Ryan

dancutlass

Hey Ryan, have you already checked your gas tank vent? Or did you for example accidentally replace your vented gas tank cap with a non-vented one? A clogged or no gas tank vent would cause a vacuum in the tank and the fuel would be hindered in getting to the engine.
If you take of the gas cap after letting it run, you will hear the air getting sucked into the tank!
Just a thought...
Good luck!

oldcutlass

Since your harmonic balancer is fubar, I would say your timing is probably off. I would fix the balancer first, timing chain is a good thing to look at since your right there, and then go back through your tune up settings.

86odls

it could be as simple as your choke flap. before i swaped my holley out for a q-jet it did that when my foot was on the gass it ran fine but when i stoped the chke flap closed and shut the car off

RXN

Choke is stuck in the open position, has never worked

RXN

Thanks guys, I'll replace my timing chain and sprockets, new balancer, then I'll try checking the gas tank vent.

Could it be a leaky intake?

droldsmorland

With a gauge tee'd into the fuel line after the pump before the carb and monitor the fuel pressure. You could temporarily mount it remote style outside of the engine compartment somewhere outside of the interior so you can watch it while on the road test.
The tank sock could slowly be picking up sediment from the bottom of the tank in which case you'll see the PSI drop off. Then once the engines off the sediment could release allowing just enough room to run again for a while. Don't rule out pinholes in the fuel line. I've seen pinholes suck air yet not leak but barely weep. Look for "dampness" on the fuel line. If you've never had the tank out I do so. You might be surprised to see what you find.

Does the car have a sediment bowl? If so did you inspect the strainer screen above the sight glass?

You said the plugs look good can you define good? White means lean.

Does it run well for the first few minutes then begin to cause trouble? If so look at the ignition too. Could be a coil or ballast resistor breaking down? Are all your grounds tight & clean?

As for an intake leak...Lets rule out the simple stuff before looking into the bigger stuff. The vacuum signal would likely be erratic if the intake or other vacuum sources were leaking.

RXN

Plugs are between a medium brown to darker brown, (a tad to the rich side). except # 8, it was black, also it was highest compression @ 150.

twintracks

Make sure that you have not lost a spring on the mechanical advance part of the distributor. This is under the breaker plate. See if the rotor is really sloppy to test. This just happened to me, and fits your symptoms.
Jerry

RXN

Rotor more extremely easy. Maybe I'll check that tomorrow after work.

RXN

So tonight, I got my spare balancer on, Rad back in. Started car up. and it was rough, anywheres under 1500rpm it wants to die. Managed to get a decent idle for maybe 4 minutes or so. just long enough to verify that the timing is correct. with the vac advance disconnected and line plugged, at 850rpm it is at 5'
as per the book.

Dinked around with the idle screws. took them out, they looked good. blew through the holes. ran them in until they seated then two turns back.

Again tried running the car. Noticed this time that the Carb is really sucking, or sounds like it anyways. Does this make any sense? Bring RPM up over 1500 and it seems okay, drop under and the carb is noisy.

So I want to rule out ignition and gas tank, any suggestions?

oh and there is small traces of water in the fuel.

MDchanic

As in little bubbles of water that you can see?

If so, then drain the float bowl (and probably the gas tank), because that's your problem.

- Eric

oldcutlass

You might pump some fuel into a glass jar and let sit for a couple of hours. The water will separate and settle on the bottom of the jar. I would base the decision pulling the tank on how much settles.

RXN

I think I'm starting to get some wheres.
I ended up disconnecting the vacuum to the brakes and plugging that line, car still ran rough and died. I have now proved my vacuum is good. So thats ruled out.

We unhooked the fuel line from the carb, ran it to a clear empty bottle. Disconnected the coil, and cranked the car. nice even shots of fuel, Clean too. so no water past the filter. Fuel is good.

Aiming to blame the carb. We took it apart again, and traced the ports to get a better understanding of what is happening, (and with the Rochester Haines manual). Started paying attention to the power piston and the power valve.

My understanding is the power piston is held up Via vacuum when the engine is at idle.
then when the engine accelerates the spring overcomes the vacuum pushing the power piston against the power valve. this allows more fuel into the venturi thus giving more fuel to through the intake.

If this power piston is sticking or not functioning properly it will keep pushing on the Power valve, flooding the intake. (My intake is wet).

The power piston was sticky. I did free it up, it feels like there is excessive slop in the shaft. So instead of putting back together and trying again, I'm going to purchase a new (rebuilt) carb and try it out. Hopefully thats my problem.

Any thoughts on this?

Sugar Bear

"I had the timing light on it, and noticed when it sputtered that the light was randomly flashing {like a miss???}"

This indicates a spark/ignition problem. See if the random flashing occurs on any other cylinders. If it does it could be weak/low primary voltage to the ignition coil, a bad coil, bad coil wire, distributor cap or rotor. Essentially anything in the secondary ignition circuit if the primary voltage is ok.

Hook up a voltmeter to the primary on the coil and see if the voltage drops when it starts to miss. If it is in the ignition, and the primary voltage stays steady, my guess would be the coil wire and/or the coil as it gets worse when warm. Coils rarely fail but when they do this is a symptom.

RXN

I pulled the power piston. Cleaned it up. One side was black. Scoreing in the bore. There is 0.004" clearance between the piston and the bore. Stupid me tho. I put some luberplate in it to help it slide better. Anyways car ran great. Idled fine for about 5 minutes before we started playing with the air mixture screws and the idle control screws. Then we managed to flood it. She's over fueling again and will detonate fuel in the cylinders. Can hear a back fire in the cylinder. (only does it after it floods and dies).

I thinking either that power piston fell out. Or that luberplate plugged a hole causeing the carb to keep adding fuel when not needed.

I do have a 2G Rochester in a box somewheres of my old 283. I'm thinking of trying that one to see.

twintracks

That sounds like a stuck or sunken float, which would be a much more common problem.
Did you check the springs for the mechanical advance under the breaker plate? This is independent of the vacuum advance.

RXN

I've switched carbs. Same issues. I pulled the intake. Stoned the heads and stoned the manifold faces. Although everything appeared slightly warped with a straight edge. The old gasket looked good. No signs of wash out or air passing. Pulled the lifter/cam cover. Everything looks good for 56 year old parts. Cam lobes aren't worn. All lifters move freely as they should. (i do use zinc in the oil). I compared the valve timing to the ignition timing. All was good. #6 intake starting to open #1 is at TDC of compression stroke. Distributor rotor points to #1 terminal on cap.

I then reversed the direction of the engine, (turning the crank by hand) both the cam and the distributor rotor turned immediatly as well. Chain is good.

Put back together. One of Dads buddies (retired HD Mech) came over and had a look. His first thoughts was timing. Then moved to think fuel. With dad cranking the engine Rudi was spraying gas into the carb. No go. Then he loosened the coil wire to the cap. Told me a larger gap means a hotter burn. It did sound better but still would not run. He looked at a plug and said replac plugs they could be fowled.

So I put new plugs in. Tryed starting the car. Big back fire through carb, singed my insulation pad.
I don't think plugged exhaust because when it does run lots of air comes out of the pipe.

Pulled the distributor cap, this time looked real close at it. Noticed a white flim on every terminal. When I put the ohm meter on it (using the 200k scale) it read 1. Then when I cleaned it up and redid it, ot read 0.00 so now no resistance. So we are going through ignition. We tested the resistants of each plug wire. (lengths vary from 18" to 28") readings varyed from 3.2 omhs to 6.5 omhs. Don't know if that's good or not. Wires are 8years old.

Pulled the points. (remember points condenser cap and rotor where all replaced last year). They didn't look so good. Cleaned the faces. Put back in. Had dad roll the crank by hand. Put the high cam of the distributor to the point pad. Points did not open. Pulled out again. Compared against a spare old set I keep in the trunk. That plastic pad that rides on the cam is considerably smaller on the one that was in the distributor.

At this point the wife showed up to get me. So tonight I'm picking up new points, New condenser and new wires. Time to try something different.

MDchanic

It sound like you are saying that up to this point you have not checked the point gap or dwell angle.
If that is true, then you probably just found your problem.

What brand and model were these points?

- Eric

RXN

Yep. Points it was. It was bought at Napa. Never checked as they were new last year. Maybe had 2000kms on them. So in my mind those are still new and good. But guess I didn't install them properly or something because they wore pretty fast. Anyways. New points. Started up. was in the process of timing it and setting dwell when the timing light quit flashing. Moved to #6 it worked again. #1 quit firing. I have new wires, cap and rotor. I'll replace all that tomorrow evening. Then should be able to get it set.

For dwell its positive lead to the coils (+) and negative lead to ground correct?

MDchanic

Way back when you checked the timing, somewhere in my mind I ASSumed, without really thinking about it, that you had also checked the dwell.

Never check just one.

I feel that this thread should be stickied as an example to others to always check the simple things first, before going on to check the complicated things.
This was a twenty minute fix, and you ended up practically rebuilding the engine.

I have had the same thing happen to me, several times, using cheap points, which is why I recommend always using Blue Streak or NOS original Delco.

I am sorry that i didn't register the fact that you hadn't checked your dwell - could have saved you a lot of time.

And, finally, to answer your question -
3-wire Dwell meter: Red - coil or battery (+), Black - ground, Sensor - Coil (-).
2-wire Dwell meter: Red - coil (-), Black - Ground (if I recall correctly).

Glad you finally found it!

- Eric

Sugar Bear

"For dwell its positive lead to the coils (+) and negative lead to ground correct?"

IIRC and it has been years, the - on the coil connects to the points. The + on the coil is the primary voltage to the coil from the ignition switch. When checking dwell the positive on the meter goes to the - on the coil and the negative on the meter goes to ground.

Can someone please confirm or correct both the primary wire orientation and the meter connection? Thanks!!!

oldcutlass

It's hooked up to the same connection as a tach, coil negative and ground.