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Want to know if you anyone has opinions or experiences with this issue. I have about 70K miles on my Curt Brown head with a majority of them with R2 cams, which where swapped from S2 cams. When I swapped to the R2's I did not notice any issues with the valve stem tips. Fast forward to now and I am building a 2.15L stroker motor with Curt and I had him freshen up the head while the motor was down. All of the cylinders sealed with no issue, but the tips of all the valve stems are mushroomed from being beaten.
I decided to rebuild the motor because I started getting a loud clacking noise from the MIVEC gear, which I was unable to resolve. I've seen many posts where people have mivec gear issues and it was definitely noise coming from the gear side of the motor. Please take a look at the pics below and let me know your thoughts.
Those pictures are interesting and also alarming. How high did you rev your motor out? And can you provide more info on what the head was built with? Guessing since its a CB head its all GSC parts nimus the springs that are Kigglys, correct?
I have an VIII, non MIVEC CB head in conjunction with a 2.15 ER bottom end and R2's so essentially the same setup you're after minus MIVEC. Fresh motor in my case just over 800 miles and honestly havent pulled the VC to inspect things yet. We know the R2s have a lot of lift and people originally were running into stem seal issues specifically with the dual valve spring setups like Supertech I wanna say they are. Obviously, you don't have those springs but makes me wonder if there is something unique to the GSC 5041 retainers that make them better suited for the R2's?
Valves are GSC, but ditched the GSC springs in favor of Kiggley when a spring broke just cruising down the interstate. I’ve revved to ~9200rpm (2L), but usually 8500rpm.
pull the springs, measure the installed height & then take the springs to a spring tester & see where the springs are sitting @ in closed & full lift pressures.
see where the springs are at relative to the specs.
since the springs are designed for a turbo application, then you have to give a basic pressure # on the back side of the valve.... so if the springs are estimated for 25psi, but you really run 50, there is another factor to consider.
im guessing the rockers are really bad looking too.
GL & please report back with seated & full lift spring pressure per your installed height.
Looks like wear from the rocker. Stuff doesn't last forever, the R2's are a serous cam with lots of lift and fast ramp rates. I'd check the rockers for wear also.
Not sure I'd be alarmed. Replace the valves, and probably the rockers, and go on your way. The level these engines get built to, they're truly a racing engine, everything has a service life. Luckily the lifters have a lot of room to take up the slack from wear like that.
The Kiggly's can handle .500" or 13mm of lift. A lot more than the 12.1mm of lift the R2's, springs aren't the issue here. Really there isn't an "issue" or a "root cause" if you will. It's just the facts of life running racing parts.
If you were having valve float issues due to fatigued/tired springs, the groove in the stem for the keepers will be beat up as well. It will be apparent, no real need to bother measuring spring pressures at that point. Just replace them.
Last edited by letsgetthisdone; Nov 6, 2018 at 08:58 AM.
It's not a setup issue and everything checks out. I have inquired with a few reputable folks and they say this can be normal, but there is also a suspicion that it could be an oil pressure issue potentially related to the HLA. It would almost seem that oil pressure to the head was affected not allowing full pressure to the lifters causing mild float. While my oil pressure gauge showed normal pressure I was also having issues with a sudden appearance of a loud clacking in the head, which I assumed was MIVEC related.
My new Curt Brown stroker 2.15L is done and the head will follow in a few days due to having to replace the guides because of the mushroomed valve stem tips. We'll see if the tips can be cleaned up or if I need new valves, but I will update when the motor is built and running. I now need to source a set of used rocker since mine are toast.
Pressure on the top side of the valve causing spring pressure to lower is a misunderstood myth. It only applies to supercharged engines and turbo engines with extremely choked up exhausts. It doesn't apply to the intake side at all.
Yes parts will wear faster like that when you run more aggressive cams but mushrooming tips is not normal. Mushroomed tips mean the rocker was losing contact with the valve tip, which could be an oil pressure issue with the lifters, or an installed height that's improper. It could also be a manufacturer defect with the valve tips if they weren't hardened right.
Since you're already doing guides, you'll need to have the seats cut as well so as long as the valves aren't mushroomed too bad and don't have any other issues, they can be reused after the tips are ground.
