GVR-4 Drilling 2g head / oil mod

[LumpyVR4]

Getting a 2g head CNC'ed for my new build. I was wondering if, while I'm getting the bolt holes taken out to 1/2 inch, whether it would be worth getting the shop to drill the oil hole out to 13mm to the depth of the oil feed, to give the head as much oil as it wants. I'm not worried about bypass oil ending up in the head as I'm fitting a Kiggly regulator. Thoughts?

 

[EC17PSE]

I believe the issue is drain of oil not oil feed, so going bigger might allow more oil to drain but the amount wont be alot more, the newer 4G63 engines have more oil drains then we got so concentrate on oil return rather then getting oil to the head ok

 

[007jimmy]

I have done this on my 1g 7 bolt head. I ported the teardrop to .120” tapering deeper to the stud hole along with undercutting the 6 bolt ARP stud. I was looking for max oil flow along with lowering the block oil pressure. (I have no squirters/BS.) Valvetrain is nice and quiet. Just make sure you clear the casting flash in all of the return holes. I have the kiggly unit as well. About 5k miles on this build so far and no issues

 

[LumpyVR4]

Definitely cleaning up flash to make it drain fast. Once lost the big ends on a 351 Cleveland due to all the oil being in the heads. Here is one of the drain holes when I pulled the head on the weekend.

 

[1990TSIAWDTALON]

I always painted my SBC oil galleys which helped oil return to the pan faster that it would on bare cast. Never had any flaking or problems. When I would tear one down, it was still orange inside like the day I painted it. Worked on those V motors good for oil return.