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Ap1 to S2000 AP2 Retainer, Valve Spring and S2000 Retainer Keepers
Hello I have a 2001 ap with 85k miles I plan to upgrade the values to ap2 and do a adjustment at the same time. I would like to buy the parts myself
I wanted to make sure these are correct and I would also like to get a good deal on them; Does anyone have a better place
I wanted to make sure I had the right part number: Does anyone have a better place to order them for?
I also wanted to make sure I have the right parts.
You should only need to do the intake side so your quantities needed are only 8 and 16.
Check out www.hondaautomotiveparts.com
You might also want to pick up this too if it’s never been replaced and your in there: Gasket Set, Head Cover - Honda (12040-PCX-305)
Last edited by Birdybog; 06-14-2019 at 03:42 AM.
Reason: Holy huge font.
I just did this upgrade on my AP1. Unless you plan on doing the work yourself, this is one of those jobs where the parts are much cheaper than the labor. I had a local Honda shop (authorized Honda repair shop...only works on Honda’s...but not the stealership) and the head tech did this job for me. Ended up taking him a whole day cause he wanted to get it done right, took his time, think it ended up being $600-700 in labor. I’ll have to check my bill. Worth the peace of mind though and in the long run, cheap insurance.
I know some are saying you only need to do intake side, but if you’re doing this upgrade I would recommend doing both sides since you will already be in there and parts for this upgrade are pretty cheap. But that ultimately is your decision. I did both sides, but I’m also OCD.
^^ yes I would just end up doing both sides piece of mind. I just wanted to make sure I had the right parts and if anyone had a better place to buy the parts
I know some are saying you only need to do intake side, but if you’re doing this upgrade I would recommend doing both sides since you will already be in there and parts for this upgrade are pretty cheap. But that ultimately is your decision. I did both sides, but I’m also OCD.
There is a reason why the intake side only is suggested and largely recommended on the forum and it's not to save time or money. I believe the thought is that the original AP1 exhaust retainers already have a higher rpm tolerance than the AP2 intake retainers. So the intake side will be the first point of failure whether they (exhaust) are upgraded - or not. Therefore why increase the potential for valve float on the exhaust side by swapping them?
When swapping the retainers if there was evidence of a significant over-rev with fractured retainers then it would probably be wise to pay greater attention to the exhaust side, but otherwise you may be in fact deriving no benefit and even limiting performance.
I’m not following your statement. The retainers are the same on both the intake and exhaust side. The F22 retainers were beefed up to prevent cracking/failure, so wouldn’t the F22 retainers be more “tolerant of higher RPMs” than the F20 retainers? Both retainers are still available from Honda and as far as I am aware, Honda never issued a TSB for F20 retainer issues. So apparently Honda feels the F20 retainers are still sufficient, however with the introduction of the F22 engine they beefed up the retainer design and lowered the redline as added insurance from cracking due to mechanical over revs.
If Honda felt the F20 retainer design was flawed or insufficient, then wouldn’t they have discontinued that part? So seems like people who swap to F22 retainers on their F20 engines are people who bought the car secondhand and don’t know the history of the car or people looking for the added insurance of having the beefier F22 retainer (or both).
I know this topic has probably been beat to death, but my opinion is if your swapping in F22 retainers on a F20 head, might as well do both sides. If Honda thought only the intake needed the beefier retainers, wouldn’t they have just upgraded the intake side? Seems like Honda was taking no chances with the F22, but was still confident enough with the F20 retainers that they didn’t pull them off the shelves.
i bought my S2000 with 107,000 miles on the engine. So I decided to replace my retainers as a precaution. I opted for the F22 retainers cause I like over engineered stuff. I also figured that if Honda thought putting the same retainer on both sides for the F22, then it was good enough for me when upgrading my F20 heads.
Ultimately, that’s a personal decision each user has to make.
The F22 retainers were beefed up to prevent cracking/failure, so wouldn’t the F22 retainers be more “tolerant of higher RPMs” than the F20 retainers?
No. Or, more precisely, yes, the *retainers* will be more robust, but it's not the retainers we care about, it's piston-valve contact. Beefier retainer = more mass for the spring to move = lower float rpm.
Basically the F20C "should" survive a mechanical overrev of up to about 10,700 rpm, at which point the exhaust valves float so much that they contact the piston. However, due to the retainer cracking problem, the practical limit is only about 10k rpm, at which point mild intake float causes the retainers to crack when the spring/valve/retainer slams shut. Note that the exhaust side might float too, but with lower overall mass/momentum (exhaust valves are smaller and springs softer than intake) the retainer can withstand the abrupt closure up until at least 10,700 rpm.
Using F22 retainers on the intake raises the rpm at which cracking occurs to at least 10,700. Now, it could also slightly lower the rpm at which float occurs, but the intake float still isn't catastrophic until well beyond the exhaust side's limit.
Putting F22 retainers on the exhaust side just lowers the exhaust side's catastrophic rpm by adding mass and making the exhaust float worse; but it doesn't offer any other improvement since the F20 retainers don't crack on the exhaust side until well after 10,700.
Again, my point is that this is a personal decision that each individual has to make. Both F20 and F22 retainers/cotters are available from Honda so clearly Honda never felt there was a need to pull the F20 retainers/cotters from the shelves. When I read the Honda bulletin, it's warning is NOT to MIX the different parts numbers, as they are NOT interchangeable. It also references that engine numbers are provided so as to ensure ordering the correct parts. However, it never states that the F20 parts are defective and should be removed from inventory. As Billman250 pointed out, Honda made changes with the F22 to help minimize the chances of a retainer failure by increasing mass/strength of the retainers and by making slight changes to the cotters. Honda also lowered redline but increased displacement of the engine, presumably to keep the horsepower at the original number while increasing mid-range torque to make the car feel like it had more oomph under normal driving conditions.
The part I am still not understanding is that when Honda incorporated these changes in the F22, they made these changes to both intake and exhaust sides of the head. If Honda felt that increasing the mass/strength of the exhaust side retainers would somehow compromise the exhaust side of the system, then it seems like Honda would have left the F20 retainers/cotters on the exhaust side while beefing up the intake side with the new parts. But Honda didn't do that, they made these changes to both sides of the head.
So to me, my feeling is that if you are going to upgrade your retainers/cotters to the the F22 parts, then I personally would do both sides as this is what Honda did. Otherwise, you now have a "hybrid system" that Honda never engineered. I'm sure there is plenty of smart folk who can provide theories as to why this is, but I'm following Honda's lead and upgraded the entire retainer/cotter system to the F22 parts. The seats are the same across the board, so Honda didn't feel a need to change the seats. The springs do have different part numbers between F20 and F22, but I'm assuming that's a vendor change rather than a spec change (NHk in the F20 and Nippon in the F22).
Here is a screen shot of the parts I ordered when I did my swap to F22 parts, to show I completely changed out the correct parts and didn't interchange any parts, as per Honda's recommendation.
Last edited by CH53Driver; 06-17-2019 at 02:46 PM.
06-13-2019, 11:56 PM
Ap1 to S2000 AP2 Retainer, Valve Spring and S2000 Retainer Keepers
Retainer, Valve Spring
