C8AE-H, CJ valves, & zero deck 390 4V valve relief question

[My427stang]

I am building a mild 390, nothing too fancy, but would like to put a set of CJ valves in the C8AE-H heads. normally a big old nothing-burger, but I am running stock pistons in this mild one

Has anyone ever used a 2.09/1.66 combo with the factory 390 4V pistons?  These are the cast 4 valve relief with no dish like the ones below and marked 390 4V in the pin area.  Example below, but not mine, found on the net. 



Specifically concerned with radial valve clearance going from a 2.03 to a 2.09, not a lot of difference, the exhaust should have plenty of room but the intake side looks pretty tight and I need to make the decision before assembly.

[machoneman]

Have zero experience Ross with your combo but (and you for sure know this!) it would still pay to mock same up (one piston, yada-yada...) with clay to check same. Here's why: another poster may say it's fine, he's done it, etc. But, with so many manufacturing tolerances (stack-up) you may be fine....or not.

Brings back a real life story. My bro' helped his pal do a real stock-bore (maybe +010, forget now)  427 FE years ago. But the used race heads had IIRC something like 2.19 BBC sized valves!

Right at fire-up, the valves hit bore edges, he lost like 3-4 intakes immediately with subsequent head/bore damage. I still have the left-over (Donovan SS I think) intakes and exhausts from that fateful build in my basement!

Wish I had been asked to help!   

[Jim Comet]

I have a 30 over 390 with C8AE-H heads and CJ valves running 2291 TRW flat tops and a 242/246 cam w/.595 lift. When I checked it with clay the intakes cleared fine but the exhausts were close enough I had them fly cut to be safe. Your cam may be the determining factor overall. Jim

[Barry_R]

Pocket location on the exhaust is a bigger problem than pocket depth.  They can hit along the back wall of the pocket.
I have (almost don't want to admit this) added some radial clearance on an assembled engine many moons ago using a die grinder alongside the relief edges.  Grease around the OD, tape everything off, and proceeded to butcher away.  Darn thing ran for years...

[My427stang]

Interesting, the relief is so big I wouldn't expect the exhaust side to be an issue, but makes sense if it's not on centerline with the valve.

[My427stang]

I decided to go 2.09 / 1.55 undercut stem with a little bowl work and a gasket match to a 1247.  Easy to do and for this mild one, will do good enough.

[Jim Comet]

Here is a picture of the exhaust cut on my 2291's. The cam is 242-246@.050 and .595 lift. Its not any deeper. Just made the eyebrow a little larger.

[machoneman]

Oh, no! I see Fel-Pro's blue silicone trimmed intake gaskets we've all talked about here, on other Ford forums, even marine forums and more. 

I guess, like Clint Eastwood's Dirty Harry said....feelin' lucky today?

And yes, I saw the other post about your 'lucky' experiences.......

[TorinoBP88]

When I did a shade tree 410 some years ago, I rolled the pockets back with a hand disk grinder and a air dremal grinder.  Ised a digital scale to keep the weight close my. I used a smaller cam, but I found both pockets too small on the Pistons I had. Don't remember the brand, Badgers I think.