68 big block very hard to start when hot.

[Kenneth B.]

Re: 68 big block very hard to start when hot.

My 67 435 will flood if I depress the gas pedal after it is hot but if I just crank it & don't touch the gas it starts fine.

[John D.]

Re: 68 big block very hard to start when hot.

On my '67 SB I had the same issue and it turned out to be fuel percolation in the carb bowls...wired open the exhaust manifold heat riser
and that helped immensely...

[Mike M.]

Re: 68 big block very hard to start when hot.

In a '71 Olds 442 (orig 455) I have I had probelms with hot starts. It would start fine if you tried to crank it soon after having killed the engine (starting was no problem in a short gas stop.) The problem came after the car had been allowed to sit for 30 minutes or even 90 minutes. It would crank and then it would die. Long story short-the problem was gas percolation in the carb (Qjet). A heat block between the manifold and the carb fixed the problem (and I also closed off one of the heat riser ports on the intake manifold). The reason that it would crank and then die was that raw gas came shooting out of the a vent on top of the carb (due to percolation). The gas flooded (literally) the front 2 bbls of the carb, killing the engine. Then it would not crank until it cooled off. Took quite an effort to discover exactly what was happening. I think this crummy ethanol gas was part of the problem. On a long trip (Hot Rod Power Tour) you cannot always fine ethanol free gas. Once fixed it went 2k miles in blast furnace heat with no probs.

[Brandon T.]

Re: 68 big block very hard to start when hot.

Thanks Mike.