The Stovebolt Site Forums The Shop Area Engine Shop Hard cold start

Since I installed a 235 in my 50 pickup it is real hard to start cold. The old 216 was really tired and smoked but ALWAYS started in about 2 revolutions of the motor even after sitting for months. I do not know any history on the 235 but I`m guessing 50k on it...it runs great and starts right up when warm. I had the carb professionally rebuilt, gas is fresh, battery, plugs, points new. Yes I`ve tried choke, no choke, pump, no pump. Could it be a bad coil?

Could your vacuum line that goes to your wipers be disconnected?

Yes,possibly coil-anything that would lower the voltage at
the plugs or increase the needed voltage at the plugs like excessive gap(likely) or high resistance wires or slow cranking speed from resistance of cold oil causing the starter to draw increased power lowering the voltage at the coil input and output.
I would verify correct plug gap if not the answer clip a jumper from bat positive to switch side of coil to eliminate possible resistance in the primary wiring and switch.If not the answer-then consider the coil and high voltage wires.Often the coil to dist high voltage wire is overlooked and can really be a killer.
with someone else cranking, allow a plug wire to spark to ground paying attention to how the spark can be made to jump-then do the same with the coil to dist HV wire the spark should be able to jump at least 1/2 inch--don't worry about color that no longer applies with resistance wires and maybe rotor.Then use a known good wire from coil output to ground and compare the spark intensity with what you saw when using the wires.
Note: The length the spark is able to jump to ground is a direct indicator of the coil output voltage--the jumper wire to bat hot post will assure proper power is available on that side of the circuit but the ground side wiring needs to be considered too.
yes the naysayers will say the coil will be damaged by our test calling for max output voltage and not giving a path to ground and that is possible but not likely in our short test and if the coil failed it probably had some failing internal insulation anyway.
If low output is detected and coil is not at fault a voltage drop test with a VOM will probably reveal some inadequate wiring/connections.
please let us know what you find.

Does the problem happen after an hour or two of cool down or are we talking several days? When you try a cold start does it catch and run for a second and then quit, or does it just crank with no signs of life?

As an ex-Renoite, knowing you're at almost 5000 feet elevation and it gets pretty cold there, make sure the choke plate closes all the way when the choke knob is pulled. Look down into the carb before you cold start it next time and give the throttle a couple of quick "gooses", you should see (and smell) streams of fresh fuel squirting into the venturi.

During cold weather, most 235's are going to require a few pumps of the pedal and full choke to get going.

Its getting lots of gas...in fact when you pump it it seems to flood and be even harder to start than not touching the gas at all. When first cranked it gives a short (like 1 cylinder firing) hope like its going to start then no more firing and has to crank for 10-15 seconds, almost like its getting fuel delivered, then it starts and runs like a champ. When I say cold I don`t mean 20 degrees, it could be 80 but the truck has not been started yet that day. The choke opens and closes fully. I do know how to start a chevy 6 as I learned to drive on one in 1966 (holy crap I`m old) and have owned many through the years.

Hmmmmm, interesting. This is what I would do, the next time you do the cold start, right after it starts to run then quits, look into the venturi and operate the throttle a couple of times to make sure you still have fuel available. I'm still thinking it's a fuel problem, you could have an internal leak in the carb or a weak diaghram in the fuel pump that's allowing the float bowl and/or the fuel line to empty between starts. The fact that it starts to run, and then after a few seconds of cranking will run, seems to rule out an ignition problem.

Small thing but important, If the problem has commenced since the tuneup,check that the points havn't had the gap closed from wear of the rubbing block.Modern "professionals" don't all have the experience with point installation to know the importance of providing lubrication at this point and a nearly closed gap will exhibit this "stumbling startup" many times but usually hot as well as cold.
Excessive plug gap is a cause of hard cold start and most modern plugs are furnished with a gap more suited for electronic ignition but too wide for point type system.
Most listings would specify .035 gap for your plugs.

Thanks for the input. Over the weekend I decided to trace the problem. My theory was to do one thing at a time and try to start it as I really wanted to know what the culprit was. I started with new plugs....BAM started right up. The old plugs (AC I think 303) looked identical to the Champions I put in, a little funky but did not really look bad to me. Before I left for work this morning I went out to start it to confirm my success (18 degrees) and it started right up. Whooda thunk it?

Thanks for the feedback, you may have helped several others to overcome a similar problem.
I too have been trapped the many ways a faulty spark plug can show up to haunt us.
But be aware that a weak spark can be hidden for a while by plug replacement or closer gap both which lower the voltage required to jump the gap.
Just for our info, did you determine what the gap was on the old plugs? and it would be intresting to know what number was on the plugs you removed.
I think the correct AC plugs would be 44,45, or 46.
Glad you got some relief.

I think the # on the old plugs was AC 303. I did check the gap and they were right on .35 and they didn`t look THAT bad to me.I did have some carb/fuel/rich issues when I first put the motor in so either that was the completely wrong plug, or they got fouled. Funny thing is, once it started it ran like a top. Duz run better now tho. Thanks for the input, if nothing else it motivated me to get off my duff and chase the gremlins.