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I am having problems with fuel starvation now that the temp. is mid 80's and up in the afternoons. It occurs after the engine is up to operating temp. and only at traffic lights either after idling for a few minutes or on slow acceleration leaving the light. If I hold rpms at 1000 or so my motor will not choke. early in the morning or later in the evening no problem. Any help would be appreciated.

What motor, intake and carb are you running? Sounds like percolation that could be helped out by using a heat insulating spacer between the carb and manifold.

Motor is a goodwrench 350 with an edelbrock performer intake and edelbrock performer 600 cfm carb. all of which was new when i performed the engine swap about 1200 miles ago. Thanks for your reply ChevyAsylum.

Yep. Aluminum bodied carb on an aluminum manifold. It'll boil the gas right outta the float bowls. I've used wood, composite or phenoilic spacers with good results. I've always used 1/2 inch or thicker.

Good luck with it.

Thanks Ray,

Will using a spacer that thick allow the dual plane manifold to work properly?

I found the correct part to do the job. Thanksfor your help!

Kim

Glad you found it. I'm gonna assume that you found the split spacer. That works fine, but even a 1/2 inch open spacer works ok with a dual-plane manifold. I'm running one on a mild 400 smallblock in my 80 El Camino. It's run great for years.

Aren't aluminum spacers used because they dissapate heat better?

Aluminum doesn't dissipate heat, it conducts it. And if you have an aluminum manifold connected to the cylinder head then the heat from the head is conducted directly to the carburetor connected to the manifold. Even stock cast-iron manifolds can have a passage for exhaust gases to flowh thru in order to warm the manifold and speed the warm-up process in winter. This is the purpose of the heat riser in a stock setup.

I've seen aluminum adapters to allow a squarebore carb to be used with a spreadbore manifold (i.e.: an Edelbrock carb on a stock Quadrajet manifold) and it's been my experience that they produce the same effect as using an aluminum manifold, which can result in percolation.

In most cases it's good to have the intake manifold warm (if not hot) to prevent condensation and puddling of liquid gasoline in the plenum. Cast iron manifolds on inline six-cylinder motors are a case in point...which is why so many old Bolts have a reputation as being cold-blooded.

But it's NOT a good thing for the carburetor to be hot, since the fuel in the float bowls must remain liquid. If the metal body of the carburetor gets too hot, the gas will boil off and empty the float bowls. This is most apparent when trying to start a hot motor, but as 61 Apache stated, it can happen at an idle in traffic. When the vehicle is moving, there's usually some air flow that helps to reduce the temperature of the carb, and the flow of gas is higher than at idle, so the problem isn't so apparent. But while sitting stiil, underhood temps can rise dramatically and fuel flow drops to a minimum. When the gas in the bowls boils off...even partially, it will appear as if the engine is starving for fuel...which it is.

So in my opinion, it's a good idea to insulate the heat of the manifold from the carburetor. This requires something that doesn't conduct heat...and aluminum is one of the best conductors of heat around. So for this particular application, it's not a good material. In other applications, it might be the correct thing, but not here.