Technical Piston to Valve Radial Clearance Help

I am in the process of putting on new AFR 180cc Street Heads on my 350. I originally had the stock 411 heads with the 1.94 intake. I think I now have a problem with the radial clearance. The intakes are now the larger 2.02". The pistons are TRW 2256 (now Speed Pro L2256F). The info online is sp****, but it seems to suggest that the piston reliefs aren't made for/large enough for 2.02 intakes. I did a clay test and clearly the vertical distance is fine, but I am measuring around .040" radially. And it's right on the relief edge as shown in the pic.

Wondering if anybody has had a situation like this, or heard of just taking a Dremel and grinding down some of the relief edge. I clearly don't have to take much off. Thoughts?? Thanks!!

[Other info: rockers- keeping the 1.5 lift, and the cam is 232@50 with .485/.485 lift also same as before]

 

It's close. I was learnt many years ago to shoot for 050" radially, .100" piston to valve on the exhaust and .080 minimum on intake if you have good valve springs.
I would think that I would go with .040" for a "bread & ****er", or mild street motor. Unless you plan on buzzing that thing up past the spring limit and get into valve float.

 

I’d hit it with a dremel to give you some breathing room. Unless it’s full blown race motor and is balanced it won’t hurt it.

 

I should mention it's for the street, and I doubt I'd be pushing rpm much past 4-4.5k.

 

Should you decide to do some grinding, when done don't leave a sharp edge. Recreate the small radius on the transition edge so not to create a hot spot.

 

I would relieve the intake valve pocket a bit with an aluminum cutter with an air grinder - using a "flame tip" type pattern. I'd also then use about a 120 grit sand-paper roll to smooth out the modifications and blend the edge just a bit. Tape off around every piston and mask off the valley area to ensure you get no aluminum or sand-paper grit into the engine. This should be an easy fix!

Here is a link to a 1/4" carbide bur - is what I use:

Carbide Bur for Soft Metals and Plastics, Round Tree, 3/8" Head Diameter | McMaster-Carr

 

If you have a Spar striped head ,& One intake Valve no matter size ,
With measuring Braze a carbide to,
To make a Fly cutter ,
Use head as a guild jig No head gasket
Drill & Fly cut piston's

 

And use a locking collar/usually with an Allen set screw on the valve stem to adjust just exactly how for down you want it to go. And I have actually used an abrasive disk glued to the valve face in a tight. The cutter brazed or other cutters would be best. . Mask everything off. Even piston top. Etc. Put the jig /head /cutting tool on and go to it.
Wes actually used to have a head cut in two just for such things. And as he said it’s not ***y but it sure works and you can see exactly what you want

 

Those look like the Good old TRWs.. wouldnt hurt to smooth all those 4 eyebrows on each piston...

 

This is a topic I’d never thought about.
I’m getting ready to have a SBC zero decked, and running heads with 2.02 intakes as well.
I think I’ll have the shop open up my valve reliefs beforehand.
Thanks for the thread!