1966-67 HCS %^&#*! wont start when hot

Have you run the car up to temperature with the radiator cap off, and tested the water temperature in the radiator?
Better yet, can you get your hands on an infrared thermometer?
http://www.lowes.com/Search=infrare...N=0&newSearch=true&Ntt=infrared+thermometers#!
That way you can check the temperature of the top and bottom of the radiator, the hoses, and various places along the block and heads, as the engine warms up.

I agree with Arlie's suggestion about the rad cap. There could be air trapped in the system, which needs to come out. That could also be the source of your gurgling sound after you shut it down. Leaving the cap off, start the car and run it up to full temp, and keep the heater fan on and the temp adjustment on heat. That will ensure that your heater core isn't trapping air either.

66hcs-conv said:

When I measured the voltage at the coil wire the wire was disconnected from the coil - no other connections to the Petronx, coil etc. That wire is where I measured the 12.xx volts.

Click to expand...

Got it. With the way you are measuring it - open circuit - you will get 12.xx volts measurement regardless of whether there is a resistor in the line or not. There is no load on the circuit so you should be seeing almost exactly the same voltage as the battery is putting out.

Having said that, I think the base problem is more likely an overheating problem per more recent discussion...

Once you've checked that there is no air in the system and that the thermostat is ok (not stuck, reversed, etc) you may want to try pressure testing the cooling system. If there are any leaks the cooling system will not hold pressure. If there are leaks that might lead you to where the problem is. You may (?) be able to borrow a cooling pressure check kit from your local auto parts stores - they usually have lots of loaner tools...

Per above, I second the suggestion on getting an infrared thermometer. They are useful and for the accuracy you need a relatively inexpensive one should be fine...

p51 said:

Got it. With the way you are measuring it - open circuit - you will get 12.xx volts measurement regardless of whether there is a resistor in the line or not. There is no load on the circuit so you should be seeing almost exactly the same voltage as the battery is putting out.

Having said that, I think the base problem is more likely an overheating problem per more recent discussion...

Click to expand...

So tell me please, how do I measure the resistance wire to see if it has been bypassed or not?

I get 12.96 volts when the wire disconnected from the coil & 12.77 volts when the wire is connected to the coil. I have a petronix II.

Thanks, Dave

I believe the circuit was modified sometime in it's past by someone.
If the Pink resistor wire was still connected in the circuit, you would read 6 to 8 volts at the coil + terminal with the Ign switch in the RUN position.

Neil

Neil,
The car you're restoring had the coil wire going through the resistor wire and an additional resistor on the firewall. That bugger did not like to start or run well until I bypassed those items, then it ran quite well.

Exactly. The car is now wired for 12V to the coil in the Start or Run position.

Neil

66hcs-conv said:

So tell me please, how do I measure the resistance wire to see if it has been bypassed or not?

I get 12.96 volts when the wire disconnected from the coil & 12.77 volts when the wire is connected to the coil. I have a petronix II.

Thanks, Dave

Click to expand...

Dave, ok first, since you have a Pertronix II, from what I understand you can safely turn the key to "run" and leave it there without damaging the Pertronix II - it is only the Pertronix I that has the issue of damage when left in the "run" position for too long without the engine running. But note that this info is just *based on my understanding*.

OK, so to determine whether you have a resistance in the wire or not I can think of three possible ways:

(1) Find the wire running from the ignition to the coil. Disconnect it from the coil. Then, with a multimeter set to measure resistance, measure the resistance on that wire from the ignition switch to the end you disconnected from the coil. If memory serves it should be 1.5ohms for the original stock "pink" resistor wire. 0 ohms means that the original resistor wire has been replaced or bypassed.

(2) Take the car out of gear and chock the wheels (see Rob's "diaper" experience :wink. Leave the wire from the ignition switch (the one you are testing) connected to the coil. Disconnect the coil from the distributor (you don't want to get a spark to the engine when doing this experiment). Turn the ignition switch to "run" (now you have a connection from the battery to the coil through the ignition wire). Put the multimeter on "volts" and measure the voltage going to the coil (with the other probe of the multimeter hooked to ground on the battery). If the points (in this case, Pertronix) are open you are looking at a "open circuit" and you should read just the battery voltage. If the points are closed you will either read something near the battery voltage if there is no resistor or something much lower (~9v or so if I remember correctly) if there is a resistor in the wire.

Now you may wonder how to determine whether the points are open or closed? You can't tell visually with a Pertroinx. But you can check both conditions as follows: Put a socket wrench on the crank and turn it far enough (half a revolution should be sufficient) to make sure the points both close and open. If you do this and the voltage stays at ~12.xxx volt while turning the crank, then there is no resistor in the wire. If the voltage drops from ~12.xxx volts (points open) to ~9.xxx volts (points closed) and then goes back to ~12.xxx volts (points open) as you turn the crank, you've got a resistor wire. What you just did by turning the crank manually is to go from an open -> closed -> open circuit. When points are closed, current flows through the wire and, if there is a resistor, you get a voltage drop. Write down the lowest voltage you see doing this. The reason for disconnection of the coil from the distributor is that turning the crank this way will fire at least one spark and you don't want the engine to accidentally start - that would be the definition of a bad day... :wink:

(3) A, final, possibly much simpler way is to just do a visual inspection to see if you still have the original "pink" resistor wire or if its been removed or bypassed. There are probably some pictures of what this wire looks like on-line. It's somewhat distinct...

Here's a good video of how the ignition system works (in this video note that there is no resistor between ignition switch and coil) and shows how the points open and close...
https://www.youtube.com/watch?v=W94iksaQwUo

Someone please comment if they know of a simpler method or see any issue with these...

franklinair said:

I believe the circuit was modified sometime in it's past by someone.
If the Pink resistor wire was still connected in the circuit, you would read 6 to 8 volts at the coil + terminal with the Ign switch in the RUN position.

Neil

Click to expand...

I think this is only true if the points are closed when doing this test. If the points (or Pertronix) are open you would see the battery voltage regardless of whether there was a resistor or not. Please correct me if I'm wrong (because then my advice to Dave is way out of whack) and let me know what I'm not understanding correctly.

Thx
James

More simple:
With the engine running (which means the Ign Sw is in the Run position) 12V at the Coil + terminal, means the pink resistor has been bypassed. Period.

If the voltage is less, than the pink wire is still in the circuit.

Neil

franklinair said:

More simple:
With the engine running (which means the Ign Sw is in the Run position) 12V at the Coil + terminal, means the pink resistor has been bypassed. Period.

If the voltage is less, than the pink wire is still in the circuit.

Neil

Click to expand...

Ah ha, with the engine *running*. Got it.

Dave, Neil's method is better. With the engine running points will be opening and closing. So you get an averaging effect on the voltage. As he said... if the voltage measured at the coil is ~12.xx then no resistor. If it falls below that then there is a resistor....

I read the shop manual (yes I read the instructions!) and the manual sez that if the resistor wire is good the voltage should be 6.9 volts. I am getting 12.xx volts, so obviously there is no resistance in the circuit.

I'm going to change the "power valve" at the bottom of the fuel bowl. Apparently that valve can cause fuel to leak into the carb.

Then I'll work on the heating issue.

Thanks everyone, Dave

Replaced the power valve, and fuel is still leaking into the bore of the carb.

I've got the carb on the bench, so I can't see the bottom of the carb to tell exactly where the leak is.

Is there supposed to be little round gaskets around the main jets? I have none.
With the carb on the bench, what stops the fuel from leaking thru the main jets, or is there not a passage for that to happen?

Can anybody offer suggestions as to how the fuel is getting from the fuel bowl into the bore of the carb?

Thanks, Dave

I found this little piece of metal in the booster venturi screw assembly. I have no idea how it got there.

For reference, dime on the left, then a little clip from the choke linkage, and the offending piece of metal.

Carb has been on the bench for almost an hour, the fuel level has dropped maybe 1/8 inch, but I am assuming that is due to evaporation. The bottom of the carb is dry.

I am going to buy a lottery ticket!

Dave,
see attached link. You must be referring to the venture cluster assembly piece 10 in the diagram. Do you the ball and weight, piece 8 and 9? These two parts keep the accelerator pump from draining into you venture. If they are not there, you have found the problem.

There are no gaskets on the main jets. The power valve diaphragm if ruptured will make the car run very rich at idle, but will not drain the float bowl if its housing and gasket do not leak.

Man I wish your car was in my shop. I would have it purring like a kitten in no time. The rebuilt carbs that come over the counter at your local Napa and such are many times missing parts or have mismatched parts. I have about 10 cores in my shop and can put one together. I may even have a C6 stamped carb body.

Rob

Rob,

Yep, I've got the weight & check ball. I got the leak stopped, and it now will start just fine when hot.

I did install a new power valve, and I think I missed on the proper size. Engine stumbles just off idle when trying to gain speed - very little pressure on the throttle. A sharp wide open throttle works OK, so I am assuming the accelerator pump is working OK.

I modified the shroud brackets, so the shroud is as pictured a few posts ago. Engine still gets hot - 210-220. I am running out of ideas.

Thanks Rob & all. I greatly appreciate your help.

Dave

Dave,
What is your initial timing set at?

Does your vacuum advance diaphragm hold when sucked on?

Does your distributor plate move when vacuum is applied to the vacuum advance diaphragm?

Are you running the vacuum line from the carb to the vacuum advance in the stock ported vacuum position?

The symptom of a flat spot right off the idle circuit is either the accelerator pump not shooting gas or lack of engine timing. The power valve can come into play. Where did you get the power valve from?

Rob

Rob,
Initial timing is at 10 degrees, with no vacuum attached to dist.

The vacuum does advance when I suck on it although not much, and I can't hold the vacuum. I don't have one of the vacuum puller tools.

Yes, the Dist vacuum is running to the right front (Passenger side) of the carb.

The dist will advance the timing with the vacuum hooked up.

With a vacuum gauge hooked to the rear of the intake manifold, I am getting 10 lbs with the car in gear. I am at 5,000 feet.

The power valve I got is a 5.5, although with 10 inches of vacuum, it probably should have been a 4.5. Although I don't know if that makes a big difference. Kinda think the one I took out is a 7.5.

Would you be open to me calling you? I got LOTS of cell time. 'excuse me, of cell PHONE time.

Dave

Dave,
Call me tomorrow anytime. (360) 377-5164. You have less oxygen in the air at 5,000 feet. Most carbs at sea level have a 6.5 power valve. So at 6.5 inches of vacuum the enrichment process starts a 6.5 inches of vacuum. Even though you have less oxygen this does not affect the power valve operation that much.

So if you drop to 5.5 or 4.5 power valve you have to have your foot in a bit more to reach the enrichment process causing a flat spot. So a 7.5 or lower power valve allows this to happen sooner with less foot in it and can assist with a flat spot.

Sounds to me that your vacuum advance diaphragm is ruptured and that will really affect the performance off a stop light under light loads. The engine sits at 10 degrees of advance and as soon as you crack the throttle just a bit it pulls in max vacuum advance of around 14 degrees bringing you to 24 degrees. This is exactly what the engine is looking for and assists in a smooth transition to low speed operation.

Rob