Bad juju happens when you try to cut corners. This isn't a particularly tricky build, but due to the decked heads and oversize valves, he'll need to clay the pistons and might need to fly cut the valve reliefs. He'll also need to carefully fit up the intake manifold, and might have to trim the manifold spigots a bit, too. Neither job is difficult or time consuming, just needs to be done.

 

If you could open up the heads a little or shave some off the piston tops them 211's would shine nicely at 10.8 static. Even at 11.1 they will make nice numbers but will be take some time to get the timing set correctly. The idle of the 211 is killer & they will make some nice #'s at that CR.

 

Ok, I have taken a little from all of the input and come up with this. I got rid of the HC oversize pistons and got a set of SE Flat Top 1550 standard 3.875 pistons. I changed valves and gained a cc on the head. I went with the .030 cometic head gasket. Here is, I hope, the final build. Give me the critical go over, lol. Will I still need compression releases?

Ported, polished and .05 milled heads, oversize intake valve, S&S springs, 79cc's
1550 standard size bore, 3.785
.030 Cometic head gasket
Andrews adjustable pushrods
Thundermax Autotune with o2 sensors in closed loop
SE 204 cam

9.93:1 Static Compression

9.35:1 Corrected Compression

191 Cold Cranking Compression

659 feet above sea level

 

IMHO, you are asking for trouble with the 204 with those numbers. I would pass on the 204 and select a cam with a later intake close, say from 38* to 42* and moving the CCR closer to 185. Woods 5-6 or 6; TMan 525/555/590, Andrews TW37, SnS 570, etc.; that is where I would be looking anyway.

You could run the 211 with those numbers but it would be soft on the bottom.

If you are hell bent on running the 204s, open the valve reliefs and/or lay back the chamber walls to achieve an effective chamber volume of 82ccs and back off the compression a bit. Find a competent TMax tuner and a tight tune and you should be fine. You won't lose noticeable TQ/HP by dropping the compression a bit but should dodge the detonation issues that are inherent with the 204s if the compression is on the high side.

Either the above or change cams. Please bear in mind that my comments are based on personal experience with the 204s; I really like the cam. What may be different in my situation is the riding environment. A few year ago, I ran an identical build but with less compression (9.8/9.25/190) in south Texas where we can see many consecutive days of 100*+ heat in July and August. Ran great, 104TQ/94HP, even on the reformulated summer fuel until the summer heat kicked in and she started to ping. Not real bad and not all the time but I could hear it from time to time. Any ping is bad and I had to do something. We pulled timing out and eliminated the ping but lost too much performance; changing cams was the only fix. If you don't have to deal with summer heat like that, you might get by with the higher compression but I think it's a crap shoot.

And yes, you should install compression releases and use them. Good luck, whatever path you take; keep us posted on your progress.