just purchased a 1963 340HP 409 engine with a matched set of 348 1960 #3758379 heads. Can I run those heads on the 409? Is it possible to have larger valves and pocket port them to flow better? I also have a set of 333 heads, bare: which heads would be best to use. Engine will be going into a 1962 chevy impala with a 700R4 transmission. Car is a street cruiser, not a hot rod.
348 heads on 409 engine
- Thread starter garys32
- Start date
Its over 1/4 inch difference down the runners in places between the two heads so the 333's are by far your best bet. I picked up a bad set of 333's just to see the difference and I was shocked. Thankfully Dave stepped in and hooked me up with a set of nice 690's which make the 333 heads look tiny.
If you have the ability to go bigger, I would do so now. Don or someone with better knowledge of size of valves should chime in here.
Mild street cam, probably a 0950 or 0951 Comp cams grind from www.Show-cars.com
With bigger valves in a 409 cubic inch motor would give you more than enough power for the street. What pistons and intake are you going to run?
On a 409,when using the 333 head in a mild street package,the 2. 09 intake,1.72 exhaust will be fine.With either a manual or automatic trans.,I's say 0 951 unless the engine in question has cast pistons.In that case,the 0950 cam.Always keep the cast piston below 5200 for any hope of longetivity.
When they open the seats up for the larger valves,have them open up the throat area just under the valves to about 85 percent of your valve seat size.Just blend in the left over machining marks.Simple procedure,makes quite a bit of improvement that will be felt in the seat[butt dyno].
Since the the 1.94/1.66 valves and the valve springs are the least capable parts in the 333 head assembly,there's really no good reason to stick with them unless they're going back into a big truck.Like Don said the 2.09/1.72 valves will support lots of power and the 2.19 valves aren't really necessary unless your after the max. power that 333's will support.