Recently purchased 1971 Cutlass Supreme. 350/2v. Automatic TH350. 2.56 rear. Starts easily when cold. Choke/fast idle seem to function well. Blip throttle, fast idle {1000 rpm} off. Idles at 700. Timing set at 10 degrees initial. Total timing is 36 degrees with vacuum advance disconnected and plugged.. With vacuum advance [vacuum advance stop installed for 14 degrees] timing is 50-52 degrees at 3000 rpm. Harmonic balancer timing mark at zero corresponds with number one cylinder at TDC. Using a innova dial back timing light. Pertronix ignition replaced points [points in glovebox, just in case]. Fires right up when cold. When it gets to operating temp it idles flawlessly. Stop and shut if off for anywhere from 3 to 30 minutes or so. The engine turns over great, but cranks at least 10-15 times before it reluctantly fires up and sputters till it clears out. What seems/sounds like it is extremely rich. It I touch the gas pedal , when warmed up, and then try to start it. It cranks and cranks but will not fire, till I leave the gas pedal alone. Then you must crank it at least 25+ motor rotations before it will reluctantly fire up. Fuel percolating in bowl? Will try to see if nozzles are dribbling after shutdown. Check *****? Have a DEI silver fuel line insulator I'll install on the hard line from the pump to the 2GC carb. Don't know if they make a thicker base gasket insulator or phenolic block for a 2GC? Car runs great otherwise. Idles great, even with the A/C on. Never runs hot. No bog or stumbling. Gas mileage is 14 city, 18 hiway. Dual 2" exhaust, with Magnaflow mufflers. Bung installation next. Have a wideband O2 & AFR gauge to try and optimize fuel delivery. All the plugs look, to me, like it is close. Every plug is a light brown on the tips and upper ceramic. Car is bone stock as near as I can tell. Hope I given enough information to help offer some suggestions. George, in south Alabama

 

Do you have a 12 volt power supply to the pertronix ignition? There instructions are not very clear on that.

 

You all probably know a lot more than me, but it might be worth it to check and clean the electrical wires to the starter.

I believe it was 2 12 or 10ga wires plus 1 big 2ga to the starter solenoid from the factory. If the connectors are dirty or the wires at at/near breaking, heat might provide just enough resistance with aging (or aged) parts to make hot start hard.

Your timing sounds totally reasonable.

Your starter or starter solenoid could be getting old. When mine start to get slow, I tend to start with the solenoid and move on to a replacement starter if the first move doesn’t fix things, but there’s a cheaper / quicker fix below:

If you see breaks or broken strands in the wires, dirty terminals on either end, wiring repair might help. The smaller wires are connected with Packard 56 connectors on the upper end, with a tiny screwdriver you can pop the terminals out of the shell and clean them with a dremel wire brush. On the solenoid end, clean up and brush up the ring terminals and the posts they mount on.

For the 2 gauge big honkin’ wire, you can source 2ga replacement or you may want to build and even thicker 1ga replacement just to overkill it. The wires and wire ends are available from Auveco, which I think is sold by Clips and Fasteners.com. Somewhere here on CO, I have a bunch of posts under my username about servicing and repairing harnesses, that should help too.

It’s just my opinion, but factory performance under most conditions assumes a fairly clean connection among electrical components for best voltage. Dirt, grease, age, broken strands can all contribute to reduced voltage making starting harder.

I’ve found that cleaning terminals with a dremel and Deoxit5 has helped most all of my electrical components work better and overheat a lot less. Sometimes I feel like restoring a car is, at some level, really really deep cleaning well designed parts.

Cheers
Chris

 

Rereading, you may also have some kind of heat-related gasket leak in the 2GC. I don’t know the design real well, but vacuum leaks can really mess up a carb.

The thing with carbs is they are __completely__ vacuum controlled. Little bits of dirt & grease can change finely tuned calibration orifices, and eventually the throttle blade bores wear a bit loose.

Another thing to try is to clean & rebuild the 2GC - not changing jets or rods, but fresh gaskets and a good thorough cleaning. If you rebuild, get the gaskets that are alcohol fuel resistant. If you still have the original (or rebuild) butyl (?) rubber gaskets, they may not be gasohol resistant.

Well played on the O2 sensor! I have them on both cars and they’re a huge tuning leap. If you can get used to Lambda vs. AFR, you don’t need to care what gas you’re putting in the car since Lambda is not fuel sensitive, whereas with AFR you kinda need to know the alcohol content of your gas - which in my state of CA is reputed to change at different times of the year.

Best of luck from here,
Chris

 

engine always cranks well. Hot or cold. Spins like the proverbial "button on the outhouse door". Will double check for a full 12volts for the pertronix. Thanks.

 

Car always [hot or cold] cranks normally. Motor spins freely. Cold, motor usually fires in one or two revolutions. Hot, have found at least ten revolutions and, quite possibly up to twenty revolutions. Always cranks at the same rhythm, no slow cranking at all. It is really bad if I tend to pump the pedal, even once, and attempt to start. Motor then has to turn over 25+ times before firing. I tend to agree it is a carb issue. Carb has a rebuild sticker and is clean in appearance. Will update thread with what helps it start better when hot. Thanks to everyone, in advance, for your help.

 

Try holding the gas pedal to the floor when cranking ( dont pump it) this helps hot start a flooded car.

if the above helps maybe the float height needs adjusting?

 

Pull a couple of spark plugs when it won't start to see if they are wet with fuel. This will help point troubleshooting toward a carb issue or ignition. Also check for spark when it won't start.

Good luck!!!

 

check your ground wires, sounds like it's shearhing for ground

 

I agree. Have to do this with mine sometimes when restarting after driving on extremely hot days.

 

Tried the hold it to the floor trick to clear a flooded engine. Engine cranks 25+ turns. Didn't want to keep cranking it. Really rough on starter life. It did finally, reluctantly, fire up; Loaded up but, did clear up. Was thinking to try ethanol free gas. May survive the heat build up since it boils at a higher temperature? Marine gas is $ .80-1.00 more here.

Another thought: Vent the percolating float bowl gas back to the tank, rather than dribbling down the intake throat?
Believe my model has a fuel return line that I may be able to tap [tee] into? Restrict the line going to the return line with a carb jet [.070 jet] ? Maybe?

George,in Alabama

 

Even if your float bowl was empty, should not take that many turns of the starter to fill it back up. One way to elminate a lot of questions is to swap out the petronix for points and see if the problem continues.

 

I'll give the points a try.and report back. Gotta figure this out. Don't think the bowl empties because if I pat the gas, it floods it worse, and there are strong streams from the nozzles.

 

12 volts there with switch on. How do you reload from "token expired"?

 

Installed "dei" insulating sleeve on hard line from pump to carb. Will see if that helps. Bung in exhaust for o2 sensor and afr reading.

 

The voltage has to be measured with a load/current flowing, check it with the car running.

Good luck!!!

 

never heard that one before. Lol

you could try one of these. I put one on my car for the same reason and it made a big difference.

https://www.napaonline.com/en/p/FIL3040

 

getting one of these. vent it in fuel return. good suggestion. where did you vent yours to?

 

installed points. re-timed. slight miss. on hot restart, identical. checked 12v with light bulb for load check. pertronix back on same start issue. closing in on it. thanks everybody.

 

I used the vapor line from the canister for a return line. I capped off the other return ports on the tank and put on a vented gas cap. This disables the vapor system but It wasn’t being used anyway. I just ran the return line to one of the center vapor ports on the tank and capped the rest. It works just fine.

 

I've read this thread several times. Sounds like resistance is increasing in the ignition system and not delivering a high enough spark when the engine is hot. When components in the ignition system heat up the resistance increases and not enough spark gets delivered to the spark plugs to fire off a "hot engine". A cold engine's ignition system has less resistance than a hot engine's ignition system. During a "hot engine" start, the resistance may become too high and unable to deliver enough (voltage) spark (until the components cool down). Once the engine is running, things are fine - easy to maintain the electrical pulse required to keep the engine running. But the issue may be the component(s) are so hot, they fail to deliver enough spark (voltage) to fire off a "hot engine".

Check the coil wire (in particular) for resistance. Check the coil itself for resistance. Check the spark plug wires for resistance. Check the spark plugs for resistance.

 

I'm still trying to determine if this is a fuel issue or ignition based on the provided data. I agree with all the ignition comments and I would check the spark with a spark tester when it's hot and won't easily restart. I would say this also sounds like most of the old carbureted cars here in CO on a hot day after they heat soak and vapor lock for 10-30 mins. I've had this same issue over and over with my BBC Chevelle. I tried venting and all types of tricks to make it better. When the engine was hot and would heat soak when I would run into the store for 15 mins....all the gas would drain from both float bowls (Holley carb) into the intake and onto the plugs. When I returned to start the engine...I would have to hold the throttle plates wide open and crank and crank to clean off the plugs. The engine would cough and sputter until all the plugs were clean and things were good again. I tried different fuels, additives, and etc. Finally gave up on carbs here mostly at altitude and our terrible fuel and went to electronic fuel injection. Problem solved!
Without checking the spark and the resistance of the ignition system components as noted.....it's hard to clearly point at one issue.....IMHO.

 

hot start

Install HEI off my buddies 67. we wired it straight to the battery. timed it. fired right up. ran for 10-15 minutes. shut it off and let it sit for 15 minutes. flipped switch twix battery and HEI on. cranked it for 10-15 revolutions it reluctantly fire, cleared up in about a minutes and ran fine after that. H-mmmmm?

 

Unclear to me what “Hm…mmm” means.

 

I think he is saying it ran better on the HEL. He said he switched to points and no improvement, so perhaps a heat induced coil issue as you mentioned. Could also still be a starting procedure issue..

 

Thanks Pat. Coil wires in particular can develop carbon “tracks” - often called. Resistance can increase significantly.

 

H-mmmm means no change with HEI, or points, or pertronix. only problem is when it heat soaks, then it does fire right up within a turn or two. It requires you to crank it at least 10 turns if you don't touch the gas. if you touch the pedal then it takes 15 turns and reluctantly fires. I could live with it, but seems like the starter is going to wear out.

 

Worded that wrong. 2nd sentence should have said: it doesn't fire right up and start in a turn or two.

 

Thinking I may try this also. https://www.ebay.com/itm/23453883440...IAAOxyQj9RS8rX which is a 1/2 inch phenolic spacer to insulate carb from manifold. Thoughts?

HEI, Pertronix, Points, 12v straight from battery, had absolutely no change to the starting when engine was heat soaked. If I hold gas to floor it takes at least 15 to 20 turns of the motor to reluctantly fire up. I shut engine off for and hour and it starts right up within a turn or two.

 

Does it have a heat riser in the left exhaust manifold and is it open?

Does the car run hot? Temp gauge?

Was going to suggest trying a 180° stat if it has a 195°.

Good luck!!!

 

Norm, you have perplexed as to how a coil wire can have carbon tracking that increases resistance. Something that causes increased resistance at the terminal connections (corrosion) I can see, but carbon tracking? That’s something that typically occurs across an insulator, such as the rotor, and creates a shunt pathway that bypasses the intended current path.


George, I agree that your troubleshooting indicates a heat related issue with the carburetor.

 

No heat riser. No gauge, just a hot light. never noticed any hot issues like boiling over. Unsure on thermostat's heat range. Even with a/c on, seems normal. Never thought of heat riser. I'll look over exhaust. Thanks.

 

The way you have described your symptoms I would be looking at a hot fuel issue. Ensure you have the insulating block (thick gasket) between the carburetor and the intake manifold. Check the assembly manual to see if your vehicle was factory equipped with the three line fuel pump set up vs what is on the car now. Ensure you do not have a high float level and the paper fuel filter is installed in the carburetor inlet nut. With the engine warm and running at idle speed is fuel trickling into the Venturi? The other suggestions about the heat raiser and hot engine temps may be helpful.

 

Another thing crossed my mind. Heat cross-over in the intake manifold super heating the carb. The three line 442 carb offers another simpler way to vent the fuel. Also wandered about an insulator twix the carb and manifold might keep fuel from perculating. Thanks for the thoughts..

 

Kenneth - Carbon tracks often occur on motorcycle coil wires from constantly overheated motorcycle engines - quite a well known phenomenon. I am not perplexed by this. It also occurs on many electrical devices when overheating is the culprit.

 

Question for Joe P
Did Oldsmobile use a heat raiser valve in the OP's application?

 

Don't forget to check for fuel dribble at idle speed.

 

Did you see if the choke on your carb is fully open when its hot? Is it adjusted right? What kind of a choke do you have? Is it the factory or you converted to electric?

 

Fully open, when warmed up. never fully closed when stone cold. Nozzles not dripping. No bog, when warmed up. Got a 1/4" insulating block coming to try and insulate the carb from the hot intake manifold. We'll see. Thanks everyone.

 

You say there is no heat riser, but then say you never thought of the heat riser. If you do have a stuck closed or partially closed heat riser that could cause your problem.