103 build 2009 Street Glide

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Looking for some more power out of my Street Glide. Here is what I have available: 103 cylinders (and pistons), SE253 cams or SE255 cams, milled CVO 110 heads, or stock heads. I have read that the SE255 cams will not do good with the milled (higher compression) heads. How would the SE253 cams do with the milled heads. Would the larger valves of the CVO110 heads perform worse than the stock heads in a 103in engine? Any tips? I would really like to use what I have available here, just not sure of the best combination.

[Mike]

H-D advertizes that the 255's will accept up to 10.0 (9.7 corrected) compression but our experiance has been that over 9.7 (9.4 corrected) detonation becomes a problem. The 255's also tend to die after 4k rpm but are really excellent from 2-4. Depending on how much your heads are milled, these could be OK if your looking for the tq emphasis to be 2-4K.

The 253's have longer duration, more overlap, wider LSA and slightly less lift. They have been, predictably, lethargic across the entire rpm range when used with stock 9.3 compression (7.9 corrected). We have not tried them with higher compression but the computer modeling shows 10.5 (9.1 corrected) to be a good start. 2-2.7K rpm tq will be lower than the 255's but will give more midrange so long as the compression is there to support the late intake closing. Top end power will not be great due to the short overlap (24 degrees). Of course this will also depend on the exhaust.

The CVO 110 heads have not been great performers (in stock form) but I believe the larger valves and slightly larger port volumes will actually help the 103 vs stock 96ci heads. This will be more true if/when ported. You'll have the advantage of the ACR's and if you push compression up, this may be a nice feature.

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Ok... I got the scoop on the heads. They are untouched, no milling, just stock CVO 110 heads. Looks like I will run these on the 103 with the SE255 cam.