rpg51

When you "inspect" I take it you are looking for valve stems that are ever so slightly lowered or sunken in the retainer compared to normal? Correct?

Billman250

During inspection, you will be looking for keepers that are sunk down inside the retainer. Even the smallest crack will sink the keepers enough that a trained eye can spot it instantly.

There are many threads and pictures about this subject over the last 12 years, it's all here.

andrewdruiz

My F20C is about to hit 200k miles and I'm going to replace ALL the retainers, regardless of their condition, for peace of mind as I begin to track this thing.

As I understand, I can't do AP2 retainers on the exhaust side of my F20C, but why did Honda put AP2 retainers on some non-US F20C's? What changed on those F20C's vs. ours that doesn't allow us to do it? If nothing was changed why would Honda engineers do this if it could potentially cause valve to piston contact?

To not take a risk, I'm going to most likely replace the exhaust retainers with new AP1 retainers, but I really want to know more about these non-US F20C's that have AP2 retainers from the factory.

Billman250

This has all been covered long ago. You can use them, but there are specific reasons not to. Search the subject and you'll find it.

jyeung528

let us know if you're able to search and find it.

i recall reading about the reason why in a thread years ago...something about...the tolerance of how high you can rev it before damage occurs, the ap1 exhaust retainers have a higher rpm tolerance...

Slowcrash_101

AP2 retainers have higher rev tolerance before cracking, and are also slightly heavier. I fail to see how this would cause an issue on the exhaust side and not on the intake side.

If the worry is valve float because of extra weight, to me personally that's nonsense. It takes quite a bit of force to coil bind the valve springs probably over 600 lbs an extra 2 grams on the retainer is like a fly landing on a 15lb cat. The valves themselves have more mass than the retainers, if anything causes valve float it's the mean speed of the valves themselves.

andrewdruiz

From what I understand, the worry is more of what will happen if a miss-shift occurs, not hitting redline during a spirited drive or on the track. The AP1 retainers are too weak to handle a miss-shift on the intake side, but can handle it on the exhaust side no problem. If you put AP2 retainers and never miss a shift during hard driving, you'll never have anything to worry about. If you miss-shift and have AP2 retainers on the exhaust side - who knows exactly how bad of a miss-shift it needs to be to cause piston to valve contact and damage the valve and possibly the motor due to the heavier retainer.

Although it has been documented that the AP1 exhaust retainers crack too, but much less frequently than the intake side. So even though it's generally recommended to do the intake side only, it's cheap insurance to buy brand new AP1retainers and keepers (although you can probably just reuse the old keepers) for the exhaust side and put them in while you have everything disassembled anyways. I just purchased new AP2 retainers and keepers for the intake side and AP1 retainers and keepers for the exhaust side for $135 shipped.

S2K632

I have a 2000 S2K with 76K miles. I have no history on the car but based on aesthetics it was well cared for. The cracked retainers are caused by mis shifts and passing the 9K rpm redline. or just jumping from a lower rpm to a higher one caused by downshifting and letting go of the clutch. Will the dealer know how to replace just the retainers? Does the cylinder head need to be removed? I plan to autocross my car once a month. Thanks

darcyw

caused by a missed UP shift by accidentally putting the gear lever in a lower gear instead of the higher gear you really wanted (for e.g.- wanting to shift from 3 to 4 at high RPM, but accidentally sliding the shifter into 2nd gear and releasing the clutch). Once you release the clutch in that lower gear, it will potentially send the engine above the red line and above the safe limit that the retainers can with stand.

it's not caused by running the car at red line normally. Its not caused by auto crossing specifically, but granted, you could misshift on the street or on the autocross course or on the track.

I imagine most dealers will follow the FSM, which means removing the head…but most dealers don't think with their heads. This can be done with the head on- use your handy friend google to search this.
Whether a car looks to be well maintained, does not mean it has or does not have cracked retainers. YOU NEED TO INSPECT. Do it with your valve adjustment.

​​​​​​​darcy

rpg51

Exactly.

I think some - including myself at one point - are under the incorrect assumption that you should change the retainers in an ap1 even if they are not cracked. My understanding now is NO - you do not need to change out healthy ap1 retainers. You do need to inspect the retainers to determine if they are cracked. You can do this inspection visually when you have the valve cover off to adjust valves. If your retainers are determined to be ok - but you later over-rev your motor - then you need to inspect again. The lesson I take from all the writing on this is this - make sure your ap1 retainers are ok and then DO NOT MECHANICALLY OVER-REV your motor.

Those with more expertise - please correct me if I am wrong! If I'm wrong I'll go back in and change my retainers.