Like clockwork. Car ran great all winter and it warmed up today. 75 degrees and I got around 200 and it started hesitating? It can idle all day add 200 however, put it in gear and bog galore until it almost dies. Vacuum diagnostics are perfect, fuel pressure is perfect (at least at idle), replaced carb and still have the problem, insulated the fuel line from the mechanical fuel pump to the carb and still have the problem. I am going nuts, what does the heat have to do with it? Can the heat affect the mechanical fuel pump? Gas going through the filter looks like someone is spitting fuel through it however its not any closer to a heat source then before I started having the problem.

I'm not sure but maybe there is an electrical problem, Ignition module breaking down with heat? or even a connetor pin expanding and breaking contact, jiggle the wires and see if you can create the problem. If it is HEI the wires to the mag pick-up go bad also.

TTFN
Mat

What year car and type of engine do you have?

This happens to me every once in a while...A couple of Viagra and I'm good to go...

Vacuum leak maybe? Check/replace any questionable vacuum hoses.

Clogged fuel filter.

Bad wires, points, plugs, cap, rotor, coil; any tune-up items..........

Carb problem? Check pump shot............

Vacuum advance on dist? Timing?

Intake manifold leak...............

its at 68 350. no vacuum leaks and both carbs I have give me the same effect. i am running a unilite. newer filter thats clean. timing has been checked and new plugs and wires. i thought it was the fuel pump which isnt that old however the bog is more like the engine completely cutting out so i think its electrical. maybe a problem with the coil or the ignition module when they get hot? i think i'll mess with those before the fuel pump. unfortunately it only does it when hot under load so i assume whatever is wrong wont show up when i am under the hood at idle.

Ahh, almost forgot. There is a rubber fuel hose at fuel tank that connects to metal fuel line. That often cracks and causes bogging. Check that hose. It may not be leaking fuel as it's not under any pressure, but it may be sucking air, which would cause bog. So check entire fuel line carefully, all the way back to tank. Also, tank pickup screen could be clogged if tank is old and has lots of rust.

If you're concerned about ignition, just borrow an HEI from someone and drop it in for a test. You can probably buy a perfectly good HEI at junkyard for $20............................

Yeah....Start with your distributor. Swap out your old one and see if you get the same results. How old is your distributor? Also, when the engine is cold, does it still bog down when you put it in gear?

it runs excellent before it gets hot. just when it gets around 200. i was going to run a new fuel line anyways (38 yr old fuel line is pretty much the only thing that hasnt gotten upgraded) so i will do it now in conjunction with the distributor and coil. i would think that its something electronic however the fuel appears to come through the filter kinda funny (kinda spits through the filter) when its hot. its not close to anything hot though.

Sorry to post the similar reply today but I want to make sure if someone does a search they can possibly catch it.

Finally! I declare this demon exorcised! After 8 months and vacuum checks, distributor, coil, plugs, plug wires, fuel filter, fuel pump, fuel sending unit, carb, timing, spacers, etc., all it needed was one wire and maybe the ignition switch (replaced them both at the same time) Engine harness was replaced for 60 bucks and ignition switch was about 20.