Need some help from someone smarter then I am Let me start off I am a reformed chevy guy always liked mopars so I made the switch.The car Im currently trying to complete is a 70 duster thats been backhalfed for a 14x32 tire hopeing traction wont be an issue.Has 4.88 gears and a 8 inch converter that will flach in area of 5200rpm.Dicided I would use what I had so I took a 383 block added 440 crank for 432 ci did all needed mods decked so piston are .005 in the hole for proper quench etc and was going to deck heads to get to 12.5 1 compression never giving a thought to exh valve to cyl clearance 4.280 bore is big compared to what im used to but lol and behold I got bit. I cut eybrows in cylinder to gain clearance for cam ultradyne 277@.050 .640 lift 108 installed 103.5 piston to valve clearance is not an issue but I dont think it will work well with 10-1 compression. I believe I have enough clearance to mill head .050 hopefully get it to 11.5-1 but still think this cam is to big Any ideas on a better cam Im thinking something in the 250-260 duration or do you think this might work reasonbnly well going to be running e85 if that makes a difference sorry to be so wordy just wanted to give as much info as I could.Also how much clearance is needed valve to cyl.Thank you

That is a tough one. I also built a 431 for a guy and I used off the shelf Edelbrock heads and when I was checking piston to valve clearence I also noticed that the valve hit the cylender wall at about .600 lift. I ended up using a cam that is .550 lift and is only 247 @ .050 and it has been running now for a few years.
If you decide to do another engine nextime use a 400 block. it is the same deminsions externally as the 383 but the stock bore is 4.340. when you take it to 4.375 it is only .035 over and you have no clearence issues to deal with. This dimension piston is a common big block size.
Good luck.

Thought of some more needed info edelbrock heads cnc ported to max wedge flow 316@700 lift hope this helps .

I would think you would want more compression for E85 than 11.5 to1.At that ratio with Aluminum heads and a UD 640 camshaft you should be able to make decent power on pump premium.
I have used that cam and it is a good grind,makes decent power in a mild big block like that.
Keith

Offset dowels, move the head towards the intake manifold. Then bevel the cylinder where the valves are and cut the heads for the compression and run that cam!
Brian

Thanks for the info on head dowels that should move it enough just barely touching now.I take it the ultrdyne 640 is a good enough cam selection to make it worthwhile.Block is decked .020 and if i deck head additional .080-.100 moveing heads up ought to help with manifold alighnment even though im sure it will still require alot of milling .