Originally Posted by gofastz
well iv ben thinking somemore, i could use the tbi heads with flattop pistons? or the double humpers "461" heads with D-shaped dish pistons? still leaning on the eddy's tbi cam with 1.6 roller tip rockers to give the engine better breathing, i know the tbi heads are not worth a darn but if the valves are wore out then mayb put some 2.02/1.60 valves in them? i have a motor here that is 87' 350 with flat tops, and the double hump heads and the performer camshaft, i could put the tbi heads on it, change the cam and all that good stuf???
Bigger valves are not the TBI swirl port heads problem and offer no solution. The Swirl Port head has a big vane that is cast from the valve guide toward the port wall that favors the inside of the cylinder. It projects into the air stream to force the flow onto the outside wall causing the mixture to develop a spin as it enters the cylinder. While all this spin is good (called swirl) the vane greatly reduces the ports ability to flow, so much so these engines cap off the revs around 4,000.
When the port is the limiting factor to flow, increasing the size of the valve has no effect because the port can't feed it. At this point there are two solutions to be used; one increase port flow or the other increase the time the valve is open. But the vane limits the former and the vacuum sensed TBI system the latter.
The vane can be ported out, there was a whole group of people who are enamored enough with this they had a web site, which I can't find anymore, but punch in Porting Swirl Port Cylinder Heads on your browser and ton of stuff will show up.
The other problems with high mileage heads are that the valve stems and guides are worn out and so are the springs. By the time you get them cleaned and crack checked, the guides reconditioned, valves repaired or replaced, valve springs replaced, new seals, head milled flat again, etc. you've put nearly as much money into them as set of new Vortecs which will out run your fully prepped Swirl Ports by an easy 30 horsepower and they don't mess with manifold vacuum doing it like a bigger cam would so your TBI's computer isn't left in the lurch trying to figure out why the engine vacuum for the RPMs and throttle position don't match the what the fuel and ignition maps are expecting to see which leads to a new chip when that happens.