Before anyone says it, I did search and read several threads. I just wanted to clear a few things up re AP2.

Background:
- AP2 motor with 50k miles
- Mechanical overrev (4->3 instead of 4->5, iirc 9900+ RPM recorded )
- Car runs perfect, no performance difference, idle same, etc.

My predicament is what is the next step. I have received some suggestions re at least having retainers checked out. Also to perhaps considering upgrading the head (this is my first money shift in 15 years of driving a manual, but I do tend to bounce off the rev limiter ).

But then thread searching turns up comments like the following from Billman:

https://www.s2ki.com/s2000/topic/805...pectionstests/


However, I have met people with dropped valves on AP2 motors, so I am not entirely clear as to the accuracy of that statement (though I fully admit I have 0.01% of Billman's knowledge). Perhaps people that have had AP2 head failure could weigh in?



To be clear, this is a track car. It sits in the garage 95% of the time unless it is going to/from the track. It has 11 track days within the last 3.5 months (when I bought it) and will continue to accumulate 1-3 days a month for (hopefully) years. If upgrading the head is a solid investment in extending the life of the motor (I am not interested in a 9k redline or any performance benefits), I am fine with that -- just don't want to toss money around for no reason. If I should look into upgrading, recommendations? There seem to be plenty of high mileage track motors and I would prefer to not fiddle with Honda's work if possible, but don't want to be penny wise, pound foolish either.

 

I would pull the head and have checked....also a great time to upgrade valves, retainers, and springs
if its race stripped its like a few hour job

I have a new supertech valvetrain in my engine with a mild port and the steel retainers from supertech

 

I just had my head rebuilt on my AP2 from the previous owners over-rev (presumably). I had no symptoms otherwise, until I started getting random misfire codes.

If i were in your shoes I would do a warm compression and leak-down test to check for bent valves. If compression numbers are good I would be inclined to agree with billmans assessment. Of course if you find yourself with a few grand that you need to spend and cant find a way, then you absolutely can pull it apart in the name of paranoia. I have requested shops rebuild something they think is just peachy dozens of times only to find later there was a hidden problem, but if your idle is absolutely perfect (not a single hiccup) and the compression numbers are solid, I suspect you are OK.

 

A compression test will help you identify if the head needs to be removed. If compression loss is found, verify where the leak is coming from with a leak down test. If compression is good, there is no good reason to remove the head. Replacing the retainers / keepers may be a good preventative step regardless if the head is removed or not.

 

Hopefully i'm not running on borrowed time here, but in my first season of the S2K challenge (2011), i did a few money shifts - bad ones too, 3->2 and 2->1 (wtf, who does that one?!?!?) on the same day/same event too, at SOWS running CCW.

I've since had a compression test - 235 across all cyclinders and had the supertech retainers and springs put in. I've also put in around 10 to 12 track days since then and another 20K+ miles. The car is an '06 AP2 and is my daily driver.

Goodluck. My recommendation is inspect with compress/leak down and drop in the supertech retainers/springs while you're in there - and get a valve adjustment.

I could be completely wrong though, which if I am, i'm hoping i'm super lucky and that it continues.

 

Having done a retainer swap before, I can vouch that you can inspect almost all of the retainers for cracks (at the top surface only obviously) with the cover off. There were a couple that we're very hard to see, but I think you could get a look with some better lighting and small mirror.

Easier than that is looking at the height of the end of the valve above the retainer. This is a better check because the cracks start at the bottom of the retainer and take time and mileage before you can see them at the top exposed side. Right away, a cracked retainer should allow the valve to sit lower, so this might be the best check. (other than pulling the head or retainers off).

I would take any data like "AP2: If engine runs fine, retainers are ok." to be extremely anecdotal. If it were me, I'd take the cover off inspect closely... if it looked OK, drive the car and reinspect several thousand miles later to make sure a small crack hasn't gone undetected and grown into a bigger one.

 

Thanks for the feedback. I'll do a compression test ASAP and think of where to go from there. Edit: and likely do a visual inspection pulling the valve cover too.

Car did just have a valve adjustment <10k miles ago, but worth checking again if taking things apart. Again, I'd prefer not to pull the head but if I am replacing retainers, might as well do springs at the same time.

Which supertech retainers/springs did you go with? Again, I'm more worried about long-term longevity/durability.

 

I would take the cover off and inspect retainers at least.

 

I would definitely pull the cover and inspect them myself, compression/leakdown test as well. If you feel that it is okay I would check again 5-10k later.

 

People scared me into believing a used ap1 = valves about to drop. So I swapped out the ap1 retainers for ap2 and...none of the ap1 retainers had cracks. Get under the valve cover, check the valve adjustment gap between the rocker and top of the retainer, and take note if any valves fit an OVERLY big feeler gauge.
A tracked car should have frequent valve adjustments anyway. An upgrade to titanium retainers or springs also comes with replacing those every 2 years or so from the nature of titanium.

AND come to the extremespeed event in 2 weeks!