Anybody done just a head swap from stock heads to fully ported without a ton of other changes. Looking for potential ET difference at the track. I can't believe even a stock engine wouldn't pick-up 3- 4 tenths. Just good bowl work and a decent valve job should give that. Maybe the mighty nailhead will humble me.
never did that, don't think anyone here did that with no other changes {hope some one did}. but just to play around here. a stock average head flows about 190 cfm vs a good ported head at 222 cfm that's 60 HP on paper. good bowl work and good valve job might get you 205-215 cfm that is 30-40 hp on paper. i think you hit it right on the button with 3-4 tenths. don't hold me to any of these numbers lol. but it's a good educated guess.
I think you are spot on Joe. The old Poston catalogue reports .3 seconds in the quarter and 30HP for a 401 with their competition port heads alone. Cheryl
Tom, I have dyno’d 3 engines. The 401 has extrude honed heads and intake, w 30 cam (yes, same lobes as olds) That made 377 hp -about the same between dq setup and edelbrock 750 My 425 with no head porting and w30 cam made 330. Dual quad intake ported by Gessler. My take was porting is important…as compression is too. I liked the torque curve on the 401- pretty flat, made 445 easy. I just got an engine from Carmen that has ported heads and 520? Lift cam. Sounds ferocious.
Just challenging myself to see what I can get out of one these old girls. Starting out with a .030 cast piston 425, block decked .030, steel .020 head gaskets , about 10.4-1 comp. Heads ported myself with stainless 1.87intake, 1.5 exhaust. No chamber work or port volume enlargement just knocked down the rough stuff in the ports and lots of bowl work and short turn radius work. Lots to do on the next set 1.94 intake, 11/32 guides, might have to break out the sonic tester to max out a set. Next engine will have custom pistons maybe some additional stroke. The car is a 65 skylark post with 4.30 gears and super turbine 300 with a 3200 stall. I will use stock GS exhaust manifolds for testing then install T/A headers. Hoping for a 12.99 on a good day. I have a Q -jet intake with 1000 TQ and Elco 2x4 with 750 street demons to test and many other combos. Should keep me busy for a while.
Tom, seen your car in Hemmings muscle car, 10.80 with your 69 455 wildcat at the GS nationals.nice, amazing.
Talk to Tom Telasco, he has some port molds made by Bob back in the day that really help visualize the head restrictions and potential port modifications.. I'm interested in how you make out, I'm starting a similar project, almost exact same specs for my 65 GS. I'll be sticking with the Q-Jet and using a solid lifter 230/235 cam, but the rest is pretty similar.
For chev's you can get porting kits or just the template 's for enlarging the ports so you don't go to far wrong anything like that for the 401? Jim
