[chrisp]

Tighten all your fuel line clamps from tank to carb.

[Kenth]

Originally Posted by dhcarguy

my car is a 65 GTO with tripower, 4speed, Lunati 230dur./460lift cam, stock#77 heads with heavy springs and HS roller rockers , it's a 66 389 block, .30 over. Pertronix coil and module in stock dist. (not sure you need all that info).
The problem is,The car starts up as always and runs great until after about 25-30 minutes when good and hot (180- 190 degrees) . then it starts to stumble. I first thought it was fuel related. I changed the 7 yr. old fuel filter. Next day took for a ride and it still did the same thing. I then replaced the 12 yr. old ignitor II coil. Took for a ride , same problem. Now I am thinking on changing the module in the dist. (which is above my paygrade lol). when in my driveway after this happens ,I can tach up the engine to 5000rpm's without a hic up.
What could be my problem??

Do you have full voltage/current needed to the coil or are you running the reduced voltage/current from the original points harness to the coil?

[dhcarguy]

OK, I pulled the carbs off and put on my spare center carb. Took it out for a long drive (35 minutes), and it ran flawlessly. So it seems the problem is in my carbs. Probably the center carb. I ordered rebuild kits from John at "pontiactripower" should have them by Sat.

Thanks everyone for your help. (I will trade my Construction brain for a mechanics brain if anyone is interested...LOL)
Dave

[steve25]

Good news to hear!

[FHummel]

Hmm, make sure your automatic choke is fully opening. Do you notice any black smoke out the exhaust? In the driveway there is no load on the engine as when you are driving, so load/no load are having two different effects. The heat you are registering seems normal. May be a plug going bad/fowling. A trick that has for the most part been forgotten is to file the ground part so that about half the center electrode is exposed when you look straight down at it. This is also good for about a 3 to 5 horsepower gain due to better ignition of the gas. Also remember that today's gas being unleaded does not give the same operation as the old leaded stuff. Also heat build-up causes coils to break down.
FHummel