hard hot start '67 L79

[William F.]

Have to turn starter for several seconds to start hot, sometimes get a missfire before starting. Excellent mechanical condition L79, all stock except for Pertronix I ignition(all voltages check out) and a Mr. Gasket heat shield between carb(new correct Holley with no flooding on throttle plates)and manifold. 15 in. vacuum at idle.Has power brakes and factory AC.Haven't checked for vacuum leak at brake booster but brakes work. Mechanic says fuel evaporating as soon as it hits inside of hot intake and should give a little pump before hitting start. Could throttle plates be too far open and not pulling enough vacuum at start to pull fuel through idle ports?Vacuum leak or other problem? Car runs fine after starting.
Thanks in advance
William Ford

[Edward J.]

Re: hard hot start '67 L79

Bill, if the car runs fine in every other respect, I would say try pumping accel. while cranking maybe once or twice. also just check the throat of carb wheile shut down hot to see if there is any fuel dripping into carb. its common to see a higher float level in the carb when the heat gets to the fuel in float bowl.

[Timothy B.]

Re: hard hot start '67 L79

William,

Is this misfire a backfire through the carburetor? I think some of the problem is todays pump gasoline that boils at a lower temperature.

I agree with Ed, look into the throat of the carburetor and see if the top of the blades are wet from fuel perculation a few minutes after hot shut down.

What is the idle RPM of the engine, as long as the air fuel emulsion screws maintain there adjustablity the blades are probably not too far open. If you open the primary blade and expose the transfer slot too much the A/F screws will cease to affect idle adjustment and you don't want this.

Does the car start like it's flooded?

[Larry M.]

Re: hard hot start '67 L79

William:

I had/have similar problems with my 1967 L-79. One was due to starter issue and the other to fuel percolation.

John Pirkle fixed the starter problem. I live with the fuel percolation problem during the hot Louisiana summers. They can be corrected if you are willing to go "non-original" on some of the fuel system components. You can wire open or remove the heat riser, install insulation plates under the carb, etc to eliminate or mitigate the fuel issues. Good/excellent carb adjustment and condition and proper spark advance are also key to this issue.

Or you could just "fill er up" with 110 octane SUNOCO Racing Gas.

Larry

[John D.]

Re: hard hot start '67 L79

william,
I had the exact same issue with my stock '67 that was solved by wiring open the heat riser as Larry describes....

jd

[William F.]

Re: hard hot start '67 L79

No fuel on throttle plates after hot soak;has a spacer replacing heat riser; has a Mr. Gasket spacer/insulator under carb. I have not blocked the heat crossover passages in intake manifold.Larry, like you , I live in the south(MS.). What non original modes are you refferring to that might solve problem?I have acces to racing fuel or AV gas-will this solve problem?
Thanks,
Bill Ford

[Timothy B.]

Re: hard hot start '67 L79

William,

Where is initial timing set and what's the part # of the vacuum control. If it's the original part #236 is correct.

Have you made sure the carburetor vacuum port is full time vacuum and not ported. Have you verified the vacuum advance is pulled to the limit at idle. Get that total idle timing up to around 28-29* and see if that helps.

I had my 67 out a few weeks ago and after a drive my wife and I stopped for ice cream and I had to crank just a little more than usual to start the engine after heat soak.

If all checks out and it's not acting flooded the gasoline is suspect then maybe try the good stuff..