Fbp is right, most of the older automobiles suffer form excessive carb heat. There are phenolic spacers offered for many applications. Most older vehilcles can benefit from these spacers. I highly recommend them.

 

Here's Why Hot Soak Starting is so problematic, and how to resolve it, if all else is in good working order.

Think of a Carb as being like a Commode or toilet bowl. It sits in place and contains the liquid it needs to function.

When it's 1st go-round and float chamber/tank is full, all works well. BUT if something should happen that is out of the ordinary, then it may not work at all.

Presume float bowl/tank leaks down. There is not enough fluid to make it work. It will require filling float bowl/ tank to get enough fluid in there to make it work. Now let us Suppose what happened is heat causes floatbowl/tank to boil over, and boilover fluids go into system loading it up with excess. Now floatbowl/ tank is not only low or empty but system already has too much fluid in it.

In vehicles, that wets & fouls plugs, soaks intake chambers & runners and the engine combustion chambers, so the system is too rich for a Op-Temp re-start. I say restart because a re-start isn't the same as a cold/ initial start up.

Everybody knows or should know it's not wise to choke hot/ "op temp" engines. When done it's sure not to start well, if it starts at all. In fact it will "flood". Conversely it's a "Beeatch" starting cold engines without rich fuel mixture=choke being used.

In a toilet, overflow can fill the lines. Either way excess fluid has to be dispensed with & float bowl/ tank refilled, before the thing can work again.

So engine has to be cranked over "lean" to rejuvinate conditions needed to hot re-start & to refill it's floatbowl or tank. Here's a tip to go with Gregs input. . . when you depress the loud pedal, don't stab it open, ease it open so slowly & so gingerly that an accelerator pump doesn't squirt more fuel into an already fuel corrupted, contaminated system. . . .

In older FoMoCo V8s, driven in hot climates, we close off one/ both heat riser ports in intake manifold, in addition to using the heat insulating base instg8r63 re-mentioned in this thread. Also Heat Shield plate I mention earlier doesn't apply to V8/ V6 engines. Their carb is right on top of the mass, but the blocked heat risers & phenolic insulator plates do work, and work well to reduce hot soak re-start problems.

With I-4 & I-6s, A deflecting heat shield plate can solve the problem. So can split exhausts or a header. Reason these work on an "I" configured engine is there is generally a mass of cast iron directly below carb where both intake & exhaust manifolds join. All that "Cast-I" works just like Grannys' ol' cast iron stove, fry pan or dutch oven. provides long lasting, steady supply, of stored, even, heat. That can cause Carbs to actually "cook" over time. springs lose tension, diaphrams brittle up etc etc.

The problem is not specific to FoMoCo either. . . . If you ever drove inline engine(s) of old you'd be familiar with this problem. Old inline flathead / "L" head engines as well as Flathead V8swere famous for the problem. In fact It even has its' own name... Hot Soak Starting .

Here's an interesting tid bit on Hot Soak Starts. In the real old days theyran updraft carburetors on almost everything because the engines were hand cranked to start. . . . now that you have better understanding of the causes of hot soak conditions can you imagine trying to fire your engine with a hand crank . . . .NOT! So Detroit used updraft carburetors. When they "overloaded" the fuel runs down and out on the ground, not up the intake plenum into the engine.

Enough Pete, sit down & be quiet !

PS: G'Day gordo,. . . When you say your midrange pulls harder now I presume you are telling me it's "stronger", rather than "struggling", right eh?

FBp

 

Yeh, pulls way better and is using less fuel too, probaly because all the fuel is going in the engine and not down the side of it. The other problem I "fixed" was the flap in the exhaust mainifold that has a heat activated spring on it was jamed in the cold position so with a little hammer work, grinding work and a bit of swearing , the little bugger now lives in the scrap pile next to my shed door waiting for its trip to the metal recycler.

 

I finally made the switch from the "Hot Soak Starting" king, the Autolite 1100 to the Carter YF and I firmly believe that the YF by nature of construction stays much cooler. It has a seperate cast iron throttle base which I believe dissipates the heat. I havent drove my truck a whole lot so I dont know all the facts yet as far as hot start problems. I have noticed the YF is a dog for the first minute or two on cold start with no choke. I havent figured out how to hook up the choke yet. The Autolite never really needed a choke, even in the Winter. It seemed to be a generally rich carburetor. I would just pull the choke out enough to speed the idle up via fast idle cam.

The Carter seems to have made the engine more responsive. Better top end. I like it...