Now before I suggest anything, I know that several of our members have installed these headers with no notable issues. If you live where it’s hot, this may be the case. If you live where it’s cold and plan to drive in the cold, this will not be the case
Now with that being said, the issue with adding these type headers, is they don’t heat the intake manifold really well like the heat riser does. This can result in drivability issues when the engine is initially heating up due raw gas not being vaporized in the intake manifold by the exhaust heat. This happens pretty fast with the heat riser in the closed position. Once heated, the heat riser closes to prevent overheating.
In addition to the headers, you will need to buy a plate to close off the bottom of the intake manifold. This plate has two ports that you would hook up either heated water from the cooling system or piped directly to the ports on the headers.
Both of these heating systems work to a point but no where near the original heat riser. If you go the water heated route, it takes longer to heat up but is a more even heat. If you heat with the exhaust, the heat is quicker, but with no way of shutting it off.
The best way, is to buy an original corvette exhaust manifold if you can find and afford one. While your at it, get the mating corvette intake manifold with three carburetors. That is the ultimate setup. Be prepared to open your wallet really, really wide!
You can always fabricate one as HRL has suggested OR, Just put on the spare stock manifold you already have!
