Machine shops to rebuild AP1 Cylinder Head
#1
Machine shops to rebuild AP1 Cylinder Head
I have a 2002 that ran without water and blew the head gasket. The engine still spins, so it seems I could get away with replacing the head gasket. I would like to know who the best machine shops at rebuilding S2000 cylinder heads? I am in SWFL but I have no qualms of choosing a recommended shop elsewhere.
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GigaSquirt (08-18-2024)
#2
Registered User
As far as I know, LHT Performance is the place to go. No personal experience but I've heard good things.
Wherever you go, make sure they use AP2 retainers/keepers on the intake side only. If they insist on doing both sides, they're wrong, and I would go somewhere else.
How do you know the bottom end is still good?
Wherever you go, make sure they use AP2 retainers/keepers on the intake side only. If they insist on doing both sides, they're wrong, and I would go somewhere else.
How do you know the bottom end is still good?
#3
Can you explain "make sure they use AP2 retainers/keepers on the intake side only." I would like to know when talking with them why I need to do this. Why is this important and why is it different than the exhaust side? Would they use AP1 retainers/keepers for the exhaust?
#4
Registered User
Can you explain "make sure they use AP2 retainers/keepers on the intake side only." I would like to know when talking with them why I need to do this. Why is this important and why is it different than the exhaust side? Would they use AP1 retainers/keepers for the exhaust?
Intake side gets AP2 retainers and keepers. Exhaust side stays 100% stock. NO AP2 springs on either side. In theory, adding weight to the exhaust valves will lower the RPM needed to make piston-to-valve contact.
Over revs go like this on a stock AP1:
-Mild over rev: intake valves float, splitting the retainers (likely around 10k)
-more severe: at about 10,700 rpm, the exhaust valves contact the piston.
The purpose of the AP2 upgrade is to raise the retainer-split-rpm over the exhaust-valve-float rpm. Bottom line, you do not want to lower that number (10,700). So after the upgrade, your engine can withstand 10,600, instead of 10k.
Over revs go like this on a stock AP1:
-Mild over rev: intake valves float, splitting the retainers (likely around 10k)
-more severe: at about 10,700 rpm, the exhaust valves contact the piston.
The purpose of the AP2 upgrade is to raise the retainer-split-rpm over the exhaust-valve-float rpm. Bottom line, you do not want to lower that number (10,700). So after the upgrade, your engine can withstand 10,600, instead of 10k.
I guess my point is, there are some "gotchas" with this engine. And doing a bunch of research on your end is pointless if the shop doesn't know anything and ruins it. So, pick a shop that's known to be successful with the S2000 engine.
Last edited by Save the Manual Wagons!; 08-15-2024 at 01:34 PM.
#5
Join Date: Nov 2007
Location: Illnoise. WAY downtown, jerky.
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Why do you need a machine shop to be involved at all if you're just replacing the head gasket?
Just replace the head gasket. Put some AP2 retainers in it yourself. That's not machining.
You can even toss some new valve seals in there.
There's nothing wrong with using AP2 retainers on both sides. Overkill, but not wrong.
Buy all your parts at a Honda dealer. Don't use any aftermarket parts.
Just replace the head gasket. Put some AP2 retainers in it yourself. That's not machining.
You can even toss some new valve seals in there.
There's nothing wrong with using AP2 retainers on both sides. Overkill, but not wrong.
Buy all your parts at a Honda dealer. Don't use any aftermarket parts.
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.Boston. (08-20-2024),
windhund116 (08-15-2024)
#7
Why do you need a machine shop to be involved at all if you're just replacing the head gasket?
Just replace the head gasket. Put some AP2 retainers in it yourself. That's not machining.
You can even toss some new valve seals in there.
There's nothing wrong with using AP2 retainers on both sides. Overkill, but not wrong.
Buy all your parts at a Honda dealer. Don't use any aftermarket parts.
Just replace the head gasket. Put some AP2 retainers in it yourself. That's not machining.
You can even toss some new valve seals in there.
There's nothing wrong with using AP2 retainers on both sides. Overkill, but not wrong.
Buy all your parts at a Honda dealer. Don't use any aftermarket parts.
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#8
Join Date: Nov 2007
Location: Illnoise. WAY downtown, jerky.
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I'm guessing you've already determined that the head gasket is indeed blown.
Download or buy a copy of the FSM. Follow the directions carefully and take the head off and check it with a straight bar, per the FSM's recommended pattern.
If it needs machining, make sure the shop does not machine it past the FSM limits. If it needs more machining than the FSM allows, you need a new/replacement used head casting...so don't even bother moving forward.
And if it does need machining, do *minimal* other work. The shop needs to follow the FSM on any services...not their instincts.
And as mentioned, buy genuine Honda replacement parts.
The key is to follow the FSM and do only what's necessary, after actually determining its necessary.
I blew my head gasket at like 165K miles, and my head was totally straight. I cleaned up the surfaces very gingerly, with a nylon brush and put the head back on, with a new gasket and new head bolts and nothing else. Worked perfectly when reassembled.
I had tracked my car with a blown HG for probably 2 track events and a few hundred street miles before I realized what was going on.
These engines are quite well built. A lot of them are ruined by shops that fix them without reading the FSM, or try to do too much, or try to use non-genuine parts.
Last edited by B serious; 08-16-2024 at 04:16 AM.
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AtlStuBird (08-16-2024)
#9
FSM?
The Service Manual (SM) is here. Download it but only print what you need as it's about 1,000 pages.
-- Chuck
The Service Manual (SM) is here. Download it but only print what you need as it's about 1,000 pages.
-- Chuck
#10
An example. Our heads have 5 angle valve seats. An unfamiliar shop doing a rebuild would likely grind them at 3 angles, and assume they just gave you an upgrade. Really it was a downgrade, and doing nothing would have been better.
They can press new guides in too far.
They can mill too much from head as already mentioned.
All kinds of reasons for less is better.
There is this knee jerk reaction of new aftermarket parts better than partially worn stock parts, or aftermarket performance parts better than partually worn stock parts, or rebuilding is better than partially worn stock. In most instances none of these notions are true for this platform. It is often true for many other cars, so understandable mistake.
They can press new guides in too far.
They can mill too much from head as already mentioned.
All kinds of reasons for less is better.
There is this knee jerk reaction of new aftermarket parts better than partially worn stock parts, or aftermarket performance parts better than partually worn stock parts, or rebuilding is better than partially worn stock. In most instances none of these notions are true for this platform. It is often true for many other cars, so understandable mistake.
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AtlStuBird (08-16-2024)