I have a strange problem. It seems that on two of my vehicles the power valves are leaking past the threads. One is a 75 F150 390 with a Holley 4 barrel and the other is a 71 LTD with an Autolite 2 barrel. For some reason after they get hot and sit for a while (say 20 minutes-like the time it takes to go in the parts store) they are both a bit hard to start. They will both sound like they will start when you first hit the key and then they will require extended cranking to start. Just like they are flooding. This is worse the hotter the engines get. After they start they run fine. Both carbs have been rebuilt. I tried putting teflon tape around the power valves to seal the threads. This helped a lot but the tape doesn't hold up. Any ideas?? Has anyone purchased a rebuilt carb from JCW? I'm thinking the carbs threads must be worn and need replacement. But I would like to pin-point the problem before I buy two carbs. Thanks.

 

Sure it's not the gas boiling in the bowls and purculating into the barrels causing the same effect? I heat shield under the carb may be in order. I have to run one on my 460.

 

Thanks LXMan1. I think i've figured it out. You are on the right track as to what was happening. I always noticed that both carbs always seemed to be wet in the barrels whether hot or cold. Today I checked the float setting on the Holley and it was too high. I'd heard to set it so that the fuel just flows out of the sight plug. But I read that it may be necessary (esp. in hot weather) to set the float a little lower because like you said sometimes the fuel will expand in the bowl and fuel line during a hot soak and overflow into the barrels causing it to flood. So I lowered my floats just a tad and presto...no more long cranking to start it when hot. Just bump the key now and it fires right up hot or cold. It also seems to have more pickup. I'll pull the top off of the two barrel and lower it's float a little, too. Thanks for the info.