So, just ran across some threads in a different group. Seems there have been at least a few people that had a variation in the head water passages that caused rapid and repeated head gasket failures. Is this just folks grabbing on to a few cases and sensationalizing them, or has it been more prevalent than a first glance indicates?

 

I have an 07 with 351 bore, no issues.

 

@durielk , you've been around these parts for a while. How many of these to you recall hearing about? I don't recall any.

My first head gasket was damaged and BB replaced it. The damage was visibly obvious.

 

I don't recall any. But, maybe some of the passages between the head and block are different a little between years. I'm thinking that may be the issue. I sent my block in and think I got the same one back, so I had no problem other than Napa giving me the wrong size head bolt thread and getting the head bolt stuck 1/2" above the head. But, I should have checked it, it almost worked!

 

Apparently, scattered throughout the different year models, there was a slight difference in how much clearance there is between the bore and the water passages. On those bikes where the clearance is minimal, apparently there have been issues. It can be remedied by having head work done--I just have to decide if I want to do that, or ride the bike as it is for experience, then "upgrade" to something with more HP.

 

The simplist way to HP is with more cc's. Having head work done isn't going to get you anywhere unless your going full race everything, even then I don't think the headwork is going to get you much except at the highest rpm's. Now if you mean having your head modified or planed for the new bore, I could see that.

 

Oh I wasn't thinking of P&P headwork, unless it was just an add on to having the coolant ports corrected (this appears to be the fix for the heads that are cut too close to the bore). But I would likely have valve seats refinished and new valve seals put in if I have to have the ports done, just because I had it off and in the shop. Porting and polishing might be fun, could change the engine acceleration characteristics a bit, but I would not expect a dramatic difference in HP or TQ with this motor.

 

Bill is sending out a head gasket so that I can compare the locations of the cooling passages with where the new bore will be. If I have one of the heads that is "off" with the cooling passages, he has a process to fix them--I'll just have to get the head to him.

 

Here is an interesting article on coolant flow, from Hot Rod magazine. Seems flow should be a bit turbulent, not laminar in flow to draw off heat. Kind of makes you wonder about if it is really bad if a gasket sticks out into the passage a bit, stirring up the flow. May not be a problem after all.

Keep Your Engine “Cool” By Managing Coolant Flow Rate

 

interesting. In the case of the heads that have had gasket issues with Bill's kit, he relays that it is a matter of some of the heads having 3 ports cut too close to the bore, and not getting a good seal. Doesn't like a large percentage of the heads, but there are a few.