MVA Heads at 15K, 120R

[Deweys]

I have been getting more and more of these coming through but they are mostly new. Now I got a set of MVAs here with 15k on them.

What I found:
Guide wear and oil passing on the exhaust stems. The exhaust valves will not return to the seat unless they are not turned from the original positions when maneuvered by hand without springs. The last 1/2" of the guide, port side, has baked carbon and valves show the same. There is a noticeable trough worn in the top of the exhaust stems. Both front and rear are equally affected.

IMHO these exhausts were headed for seizing, same as the 07 CVO original pre-program heads do. These will be fixed with AV&V bronze manganese guides, .0014 in & .0016" clearance ex and high quality viton seals. Clearances now are .0019-.0024".
Stem seals are K-line.

[mitchdm]

This does not surprise me ~ I have never had a twin cam rear head make it to 41k ~ This experience has been across an 06 SE ultra traded at 93k Rear exhaust Valve guide failed at 40 & 80k ~ a 10 LTD sold at 71k rear exhaust valve guide failed at 30k less than a year old. After the replacment on the 10 I had FM work a set of heads for me & no issues since. I have already sent a set of 110 heads to be reworked since experience has taught me that Next Summer I will need a set ~ All three failures I had were actually cruising done the interstate one on decel ~ turning of cruise to exit ~ and two on accel to pass.

IMO the heads are the overall weak link on the late model twin cams

[Deweys]

I do not see this on any of the late 103 and 96" OEM heads with 7mm valves.
I used to do a "blueprint" package which used the original guides but no more on any of them. I can set the valves tighter and sealing is better on the seat and oil control for the long haul.