I'm sure this has been done many times. Just looking for feedback on people that have run the MW 4 bolt valve covers on 440 6 bolt heads and how well they sealed? Best gasket? Any other issues?

Used 6 bolts on the 4 bolt heads on my kids 62 300.No problem.Ive seen and run 4 bolts on later 6 heads.Only gaskets we use are Mr Gasket ultras dry.Rocky

I've seen many M.W. four bolt valve covers that had the extra lip on the corners to help seal the original V.C. gaskets better, my 1963 415 HP Belvedere had them stock I've also seen some later 1966 to 1969 six bolt V.C. welded up to look like original M.W. four bolt covers

I believe somewhere mid 63 they went from 4 to 6 bolt.
You did not state what year you need info for.

The only ones I see reproduced are 4 bolt.

Not so, they went to the six bolt valve covers on all the heads in 1964, Max wedge or 361 two barrel motors
Mopar did make a limited amount of 425 HP Stage Two 426 in 1963 for drag racing only, bigger carbs, bigger cam, hand modified combustion chambers on the 286 heads for better flow and hand modifeid intake manifolds for the the bigger carbs.

Not all 4 bolt are max wedge also.They came on all early BBs.Rocky

There was two versions of the early 4 bolt valve covers, those for non adjutable rocker arms with the stamp steel rocker arms and the other type was for the stock Mopar adjustable ductile iron rocker arms They are not interchangable You can run the adjustable covers on the non adjustable rocker arm heads but not the other way around

What is the difference between the two covers?Is there more clearance on the max wedge cover?

I never measure the hieght differences between the two covers but if you tried to run the stock ductile iron adjustable rocker arms under the stock covers off a hydraulic cam motor the adjusters would hit the oil baffles inside those covers just like they did and do on the later 6 bolt non adjustable covers

Was going to do this for the period look when I put a cross ram on the car. However, sounds like I may have some issues with rocker clearance. I'm running Crane roller rockers.

Just looked at a set a few weeks ago. Guy was running roller rockers and had cut the oil shields out for clearance.

I'm planning on running my 915's with a set of Isky ductile rockers...The difference in the v/c's your talking about does it only apply to stock covers?
I have a set of NOS Offenhauser finned 4 bolt v/c's I was planning on using...

If I'm not mistaken the "taller" valve covers have an oil fill tube that is 1/2" taller then stock. However I do not know what the measurements are as I do not think I have any more of the 4 bolt valve covers to get the measurement.

Yes you can,these were originally 4 bolt with the blank end tabs not drilled for the end bolts.

So back to original question. I plan on running a set of the repro 4 bolt valve covers on 440 heads. Sounds like they will seal just fine. However, I may have to modify a bit to run with Crane roller rockers?

These particular valve covers:

http://www.manciniracing.com/19mobigbl426.html

I have a set of the 4 bolt covers somewhere & also offy. finned ones.

If they don't have the extended M.W. corners on them they will probally leak in the corners on the 440 heads