Valve to bore clearance...........

[Tommy A]

Motor is 428 @ 4.160 bore, has not been honed for pistons yet, with head on block with exh. valve pushed till retainer hit the guide there is .020 clearance between the valve and bore. The heads are Edelbrock 6005 with 1.750 exh. valves. Our question is will it work like this or should we take a little off the valve. I'm helping a friend and we want the motor to run good. It will be a 462 stroker any thoughts, Blair,Brent , anyone..........Thanks.............Tom

[blykins]

I typically see about .700-.800" retainer to seal clearance on an FE head with 1.850-1.900" install height.  If you're pushing the valve down until the retainer hits a bare guide, then you will probably have a little more than that. 

If you're not planning to run a camshaft with lift approaching those kinds of numbers, then you shouldn't have any problem that I can think of right now.  I will say that I don't think I've ever ran an exhaust valve that large on a 428 bore though.

[Tommy A]

Brent, if we go with door #1 the lift is .700/.688  Do you think that .020 is enough valve to bore clearance???  Thanks....Tom

[Barry_R]

That .700 is gross?  If so you will gain a little with lash and a little more with deflection.  But you will lose some of that in operation because the valve kinda "corkscrews" down the hole.  Are you checking with a head gasket in place?  That makes a bigger difference than you would expect.

[blykins]

How much room do you have between the retainer and guide with the valve shut?  And is the seal on it?

[jems68]

Hey Tommy, I have run that exact set up with Edelbrock heads that have 2.25 intake and 1.75 exhaust valves on a 4.160 bore 428 block with 4.250 stroke. My cam has a .572 lift. The car has been to three Hot Rod Drag Weeks and the motor has been in the car for seven years. Things are close but so far I have had no problems

[Tommy A]

Mr.Jack, I did talk with you about that @ DW2017 down @ Cordova, I guess its a go!!  Hopefully You can get the new heads figured out for the mustang...Good luck.............Tom