1963 cold and hot start problems

[Jeff C.]

Having trouble with both cold and hot starts. Cold start requires pumping the throttle and cranking for 3 to 4 seconds. Hot start requires throttle to the floor and 5 seconds of cranking then the engine runs rough for about 30 seconds. The car has the original 340HP engine with all of the correct external parts on it and runs fairly well in normal driving. It was rebuilt by one of the previous owners some time before 1999. I have done the following to try to improve the start problem:
-Did a compression check. All cylinders 160 psi to 180psi.
-I rebuilt the AFB 1 year ago it has the correct jets and metering rods. I just took the top off last week and reset the floats.
-I reset the valve lash to .008 I and .015 E (duke Williams) I have no way to verify that the cam is a 097.
-The vacuum can is a B28 and is working correctly. Initial advance is set at 14 deg BTDC with the vacuum plugged.
-I currently have an early Petronix electronic ignition in the distributor. The distributor is in good shape with no shaft play issues. My next step will be to reinstall the breaker points to see if that helps.
- Choke works and is set correctly when cold the RPM is 1200 to 1300.
- The car has no overheating problems as I installed a new Dewitts restoration aluminum radiator
-The only other issue that I will be addressing is at WOT the engine starts missing about 4500 RPM. BTW the rear end has 4:11 gears.
Any help will be greatly appreciated,
Jeff

[Edward J.]

Re: 1963 cold an hot start problems

Jeff, On cold start make sure the choke butterfly is closing all the way after you push accelerator once to floor, without choke closing hard starts are common. another thing is the gasoline will tend to evaporate after sitting a week so longer cranking times will happen until the float bowl fills. Hot hard starts can be related to ethanol fuel, my 63 will crank a little longer after a 1/2 run and when I try to restart I find about 3 to 4 seconds to restart. Also make sure no fuel dripping out the throttle blades after shut down. I had this problem and lower my float level about 2/32ths from the factory setting.

[Terry D.]

Re: 1963 cold an hot start problems

What plugs are you running and have you checked both the plugs and wires? What about the coil?

[Jack M.]

Re: 1963 cold an hot start problems

Advice from 'The Carburetor Shop'

HARD STARTING, COLD
HARD STARTING, HOT

[Michael W.]

Re: 1963 cold an hot start problems

Hard start hot and cold plus a high speed miss could be the pertonics unit.

[Frank D.]

Re: 1963 cold an hot start problems

More likely an ignition coil; however I think your problems are fuel related....that advice Jack posted above from the Carburetor Shop is great stuff for sure. First though, make sure your choke is fully closed when you blip the gas on a cold engine; also check you get a good double shot out of the squirters when you blip the throttle as well (look down the bore). Hot start issues is almost certainly percolation -- you can verify with a cheap I/R temp gun pointed at the fuel bowls - if they are getting north of 148* or so that's an issue. You can buy a 1/4" phenolic spacer to put under your AFB to isolate it from some heat. Otherwise, you might have to block off the intake manifold exhaust runners with a fuel injection gasket set; that is usually the most effective. IF YOU DO that -- you will need to wire open, or eliminate, the passenger side exhaust manifold heat riser valve.

[Nick K.]

Re: 1963 cold an hot start problems

I have a '63 340 HP car and have the same problem when starting the engine cold. I agree it is just a matter of the fuel boiling/evaporating out of the bowl. Any known source for a phenolic spacer for an AFB using the original 129 intake which as you know has a heat crossover (that in my case is not blocked)? I have also wired my heat riser open but that didn't help the dry bowl syndrome. I am having difficulty finding a source for this application. Thx...

[William F.]

Re: 1963 cold an hot start problems

Do you bend one of the "choke rods". or turn the part on side of carb that is inscribed with "lean" or "rich" to richer side to get choke to close completely. My choke moves freely but gets to a stop before it closes completely. Chevy manual is confusing to me in this regard. I don't think the piston in the choke control is carboned or frozen up since I can move the choke blade freely but can't push it (or set it with carb linkage/foot pedal to floor) to completely closed position.
Thanks

[Edward J.]

Re: 1963 cold an hot start problems

Nick, I have a friend with a 63 300hp engine and it still requires a long crank time when starting after sitting a week or two, What he'll sometimes do, Is take some fuel and fill the bowl before starting. I don't believe the spacer is going to help. My 63 340 car has hard starts after a hot soak and the float bowl empties when sitting for a period of time. I have just leaned to live with it. I am hoping some day the Ethanol will be removed for gasoline. The car other wise runs like its suppose to.

[Nick K.]

Re: 1963 cold an hot start problems

Nick, I have a friend with a 63 300hp engine and it still requires a long crank time when starting after sitting a week or two, What he'll sometimes do, Is take some fuel and fill the bowl before starting. I don't believe the spacer is going to help. My 63 340 car has hard starts after a hot soak and the float bowl empties when sitting for a period of time. I have just leaned to live with it. I am hoping some day the Ethanol will be removed for gasoline. The car other wise runs like its suppose to.

I agree the cold start could be partially due to the choke not operating as it should due to the choke pull off piston sticking in the bore of the choke housing after repeatedly cleaning and readjusting over the years,,,,,The other issue and more importantly is I am having a problem with heat soak / vapor lock.. when the engine is hot and idling at a stop light for example and ambient air temp is high it will occasionally stall out and have difficulty restarting until it cools down a little. I think in this instance the fuel is boiling either in the fuel line or the bowl. My theory is if I installed a phenolic spacer it would reduce the carb body temp signficantly and hopefully eliminate fuel boil in the bowl and vapor lock. Another question is whether it is possible to use a phenolic spacer on an intake with a functioing exhaust crossover.

Thanks for the input Ed.

[Edward J.]

Re: 1963 cold an hot start problems

Nick, I have never tried the spacer, I believe you'll run into a couple of problems first the fuel line will have to altered to Carb, second you'll need longer studs, and finally will the air cleaner clear the hood when shutting? and maybe the hot air tubes.

[Michael W.]

Re: 1963 cold an hot start problems

I agree the cold start could be partially due to the choke not operating as it should due to the choke pull off piston sticking in the bore of the choke housing after repeatedly cleaning and readjusting over the years,,,,,The other issue and more importantly is I am having a problem with heat soak / vapor lock.. when the engine is hot and idling at a stop light for example and ambient air temp is high it will occasionally stall out and have difficulty restarting until it cools down a little. I think in this instance the fuel is boiling either in the fuel line or the bowl. My theory is if I installed a phenolic spacer it would reduce the carb body temp signficantly and hopefully eliminate fuel boil in the bowl and vapor lock. Another question is whether it is possible to use a phenolic spacer on an intake with a functioing exhaust crossover.

Thanks for the input Ed.

Vapour lock occurs exclusively in the fuel pump and inlet, not the carb. Percolation happens in the carb, but rarely in while the engine is running.

To see what's happening peer down the carb throat while the engine is idling. If it's percolation, you'll see fuel spilling as though there were a leak. If it's starving for fuel, the fuel pump area needs attention.

[Edward J.]

Re: 1963 cold an hot start problems

Vapour lock occurs exclusively in the fuel pump and inlet, not the carb. Percolation happens in the carb, but rarely in while the engine is running.

To see what's happening peer down the carb throat while the engine is idling. If it's percolation, you'll see fuel spilling as though there were a leak. If it's starving for fuel, the fuel pump area needs attention.

Nick I agree with Mike, Percolation is in the carb. I forgot to mention that I lowered the float level about 2/32ths from the factory setting because my 63 was dripping fuel after shut down on a long run and hot days.

[Timothy B.]

Re: 1963 cold an hot start problems

Nick, Have you wired the heat riser open? Try the engine with 16* initial timing and see if that helps and use the aggressive vacuum advance control?

[Jaime G.]

Re: 1963 cold an hot start problems

Why don't you try something real simple.
Don't use fuel with ethanol (yes its available)
try some racing fuel once in awhile.
Both of my suggestions work for me in my 6 cars.
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