F134 Exhaust Valve Help

Hello kind folks. I've removed the exhaust valves from this F134 block. Compression was poor at 35 PSI on 1, 2 and 4 with 75 on 3. On the left is a pitted valve, on the right, one of a set set of Eatonite NOS valves I had kicking around. Measurements confirm that I have exact replacements and the stem diameters match.

I'm measuring 0.071 for both the take out and NOS replacement. I'm feeling like my valve guides are in good order since there's not a discernable difference in tolerance.

I'm going with Neway cutters., but I'm struggling with which size pilot(s) I should purchase. Can someone help me here? Here's Woodwards pilot page; https://www.cylinderheadsupply.com/ne140sepifrs.html

I'm grateful for the help as always.....Pete

 

.371"?

 

Thanks for the reply. My thought was that it needs to be ever so slightly larger so it fits snugly? Is that large enough?

 

The pilot-to-guide clearance should be .0002˝ or less for accurate machining. One way to achieve that is to use a high-pressure lubricant on the pilot.
For this you will need to know the exact ID of the guide/guides. There is a bunch more to consider. For the price of tooling and time, you could have a machine shop do it while you work on other things. IMHO

 

I was just checking .371" vs .071" for the stem. I think i did the heads on my 4.3 at the local college with all the typical sbc stuff ready to go. Then I used a valve scraper on the old valves. I was expecting to put true vortec heads on it soo the ol kidney bean heads were supposed to be practice...