The Stovebolt Site Forums The Shop Area Engine Shop 216 hard to restart, ideas?

My '52 Chevy 3100 with 216 has become almost impossible to restart when the engine is warm or even just sitting out in the warm sun. Spins over but doesnt start. Fuel filter had fuel in it but I'm not sure if I'm experiencing 'vapor lock' because in a last ditch effort I tried blowing in the fuel tank and what do you know, finally I got it started. Has anyone else had similar problems? Maybe I should also do a compression test? Thanks for any advice guys

Sounds like the fuel is boiling in the carb bowl. Is carb still mounted to it's isolation plate?

Are all of the fuel lines installed in there original locations?

Is the exhaust heat riser damper rusted closed forcing heat up to the intake manifold?

Mike B

I agree it sounds like carburetor boil-over.
But, hot weather tends to bring out other problems that may not be apparent when the temps are milder...

Mike yes the carb is mounted to the isolater plate and fuel lines are original in the proper location. How warm would you expect 'boil over' to occur? I drove the truck to a show yesterday, started right up in the morning when it was cool. The temperature was in the low 80's and the truck sat on a blacktop all day. I'll have to look at the heat riser, not very familiar with it.

When my 216 is warm and has sat for a period of time, it will not start without some throttle input. I put the gas to the floor and hold it there for about a minute. Then with my right foot I hit the starter. It will then catch quickly and I release the gas pedal right away. That is the only way it will start and I think this is normal and acceptable.

Because of the intimate contact between the manifolds it's common to have percolation problems. If the weight on your heat riser is in this position with the engine warm you're OK, or at least as OK as you're going to get with that manifold set-up. If it's rotated clockwise from that it's allowing excessive heat to cook the carburetor. What happens when you shut the vehicle off hot is the fuel in the bowl boils out and fills the intake runners with fuel rich vapor. When you try to restart it's like trying to start a hot engine with the choke on. My hot restart ritual is a bit different from truckernix's in that I don't touch the gas pedal, I arch my foot over it and press the starter pedal only until it catches. My reasoning is I don't want to put any more fuel into an already rich environment. I understand his too in that with the throttle plate open it'll pull the rich mixture out more quickly. Experiment until you find what works for you but you first need to make sure your heat riser isn't stuck in the wrong position.

Ok guys it appears you all were indeed correct about the heat riser. After having a look at it I found it is stuck, and I assume there should be a spring on the right side of the manifold, which is missing. So now I guess all I need to do is free it up and replace the spring? Thanks for the help!

Is the truck 6V? If so, what size are your battery cables?

Well SWEET the truck is partially converted to 12v. Generator has been converted to 12v, 12v battery, ignition coil is still 6v with voltage reducer and starter is still 6v. As for battery cables I think they are original.

I don't think the heat riser is having an affect on starting when your truck is only warm from sitting in the sun.

Truckernix I will definitely give your method a try and see what happens. I normally pump the gas a few times before starting, the other day I did hold the gas down for a while and still nothing. Hopefully I'll get it sorted out soon, thanks

After a close look at the heat riser, it seems though it is seized in the open position. I've already tried heating it up with a small propane torch and it will not budge. Any ideas on what I can do to free it up?

They usually stick in the closed position because that is the position when at rest.
To free it up get the engine really warm, anoint the bearing area of the shaft often with preferrably Kano Kroil or other penetrant and tap the shaft in all directions as well as the counterweight and try to rotate it often with pliers or tapping the cweight.The key is be patient, it didn't sieze overnight it may take persistance to free it.

That advice of "tap in all directions" is a great clue. Sometimes tapping the ends of the shaft is a vital part of freeing it. Patience is really important as you don't want to fracture the manifold.