Really need help w/ head gasket thickness/piston to valve clearance & timing chain
06-27-2018, 10:14 PM
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Really need help w/ head gasket thickness/piston to valve clearance & timing chain
Hi, I desperately need some advice...
A month ago I wrote a post on how my 2006 S2K blew a head gasket which warped the block and head. Roughly .002" - .003" were taken off the block, but the machine shop messed up my head. The first machine shop used a freaking belt sander to resurface the head and it didn't come out flat, and they also cut the valve seats using worn valve guides. I then took the head to a different shop who installed new valve guides and recut the valve seats. They also resurfaced the head flat, but didn't pay attention to how much they took off when doing so.
I measured the head height (head gasket surface to valve cover gasket surface) w/ calipers. Honda says you can only take .008" off of the head & the service limit for cylinder head height is 4.124" - 4.128". The intake side of the head measures 4.124" - 4.126", so it's still within the low end of the spec. However, the exhaust side measured around 4.118" so that's .006" below the low end spec. What's worse is the area around the timing chain measured around 4.113" - 4.118". If I take the lowest measurement, that's .011" below the low end spec of 4.124"
It's really hard to get a prefect measurement becasue it's hard to place the caliper jaws perfectly flat when taking measurements, but I think this is the most accurate I can get. It appears the head is thickest in the back (side closest to the firewall), and that it gets thinner/shorter on the exhaust side as it gets closer to the timing chain area - hopefully that makes sense.
For a month I've tried to find a used head (AP1 or AP2), but I can't find any w/o damage and none are local either. I've already lost a ton of money on my original head & don't want to end up buying a used head w/ damage, only to find out I can't use it also and have lost more money. A brand new bare head from Honda costs $1800 w/ shipping (I have my own valve train so all I need is a bare head), but that's a ton of money.
I can't afford a new head, and I can't find a used one that's a safe bet to buy. I was wondering if using a thicker head gasket and Ballade Motorsports adjustable timing chain gear (allows adjustment up to 3 deg) would work. Obviously it's not the best solution, but it might be my only option. What do you guys think?
The OEM gasket is .030", and Cometic makes a .036" and a .040" head gasket. If I use the .040" gasket that gives me an extra .010" of height/thickness. That extra .010" would bring my intake side measurement up to 4.134" (4.124" + .010" = 4.134"), the shorter exhaust side would increase to 4.128" (4.118" + .010" = 4.128"); and the lowest area measurement near the timing chain would come up to 4.123" (4.113" + .010" = 4.123") which is just .001" shy of the lower end service limit of 4.124".
Honda's new cylinder head height ranges from 4.132" - 4.136". Since the .040" thick head gasket brings my head up to 4.134" (intake side), 4.128" (exhaust side), 4.123" (timing chain area); it means the intake and exhaust sides would be within spec and the timing chain area would be just .001" shy of the lower end spec; and I'm guessing the Ballade Motorsports adjustable timing chain gear would help out with any extra timing chain slack.
I figure based on the measurements I got that w/ a .040" thick gasket I wont have any piston to valve clearance issues even w/ vtec and my biggest issue will be some timing chain slack. So what do you guys think? Is what I'm thinking correct and do my calculations make sense? Is the .040" Cometic gasket + adjustable timing chain gear the way to go since I can't find a decent used head and can't afford a new one?
Or is it simply not worth the risk and is it better to just take out a loan and buy a new head from Honda? What would you guys do if you were in my shoes? If I guess wrong, then I'll need a whole new motor instead of a just a head. Any advice is much appreciated.
A month ago I wrote a post on how my 2006 S2K blew a head gasket which warped the block and head. Roughly .002" - .003" were taken off the block, but the machine shop messed up my head. The first machine shop used a freaking belt sander to resurface the head and it didn't come out flat, and they also cut the valve seats using worn valve guides. I then took the head to a different shop who installed new valve guides and recut the valve seats. They also resurfaced the head flat, but didn't pay attention to how much they took off when doing so.
I measured the head height (head gasket surface to valve cover gasket surface) w/ calipers. Honda says you can only take .008" off of the head & the service limit for cylinder head height is 4.124" - 4.128". The intake side of the head measures 4.124" - 4.126", so it's still within the low end of the spec. However, the exhaust side measured around 4.118" so that's .006" below the low end spec. What's worse is the area around the timing chain measured around 4.113" - 4.118". If I take the lowest measurement, that's .011" below the low end spec of 4.124"
It's really hard to get a prefect measurement becasue it's hard to place the caliper jaws perfectly flat when taking measurements, but I think this is the most accurate I can get. It appears the head is thickest in the back (side closest to the firewall), and that it gets thinner/shorter on the exhaust side as it gets closer to the timing chain area - hopefully that makes sense.
For a month I've tried to find a used head (AP1 or AP2), but I can't find any w/o damage and none are local either. I've already lost a ton of money on my original head & don't want to end up buying a used head w/ damage, only to find out I can't use it also and have lost more money. A brand new bare head from Honda costs $1800 w/ shipping (I have my own valve train so all I need is a bare head), but that's a ton of money.
I can't afford a new head, and I can't find a used one that's a safe bet to buy. I was wondering if using a thicker head gasket and Ballade Motorsports adjustable timing chain gear (allows adjustment up to 3 deg) would work. Obviously it's not the best solution, but it might be my only option. What do you guys think?
The OEM gasket is .030", and Cometic makes a .036" and a .040" head gasket. If I use the .040" gasket that gives me an extra .010" of height/thickness. That extra .010" would bring my intake side measurement up to 4.134" (4.124" + .010" = 4.134"), the shorter exhaust side would increase to 4.128" (4.118" + .010" = 4.128"); and the lowest area measurement near the timing chain would come up to 4.123" (4.113" + .010" = 4.123") which is just .001" shy of the lower end service limit of 4.124".
Honda's new cylinder head height ranges from 4.132" - 4.136". Since the .040" thick head gasket brings my head up to 4.134" (intake side), 4.128" (exhaust side), 4.123" (timing chain area); it means the intake and exhaust sides would be within spec and the timing chain area would be just .001" shy of the lower end spec; and I'm guessing the Ballade Motorsports adjustable timing chain gear would help out with any extra timing chain slack.
I figure based on the measurements I got that w/ a .040" thick gasket I wont have any piston to valve clearance issues even w/ vtec and my biggest issue will be some timing chain slack. So what do you guys think? Is what I'm thinking correct and do my calculations make sense? Is the .040" Cometic gasket + adjustable timing chain gear the way to go since I can't find a decent used head and can't afford a new one?
Or is it simply not worth the risk and is it better to just take out a loan and buy a new head from Honda? What would you guys do if you were in my shoes? If I guess wrong, then I'll need a whole new motor instead of a just a head. Any advice is much appreciated.
07-01-2018, 11:21 PM
#3
I think I would try what you are suggesting. Adjustable timing chain gear will be able to put your timing exactly back to spec.
You will also be probably fine regarding p2v clearance since your math makes sense. If you want to be 100% sure, clay the motor.
What I would check for peace of mind though is how reliable people found the .040" hg to be, no idea if it's used commonly and/or any good.
You will also be probably fine regarding p2v clearance since your math makes sense. If you want to be 100% sure, clay the motor.
What I would check for peace of mind though is how reliable people found the .040" hg to be, no idea if it's used commonly and/or any good.
07-02-2018, 05:17 AM
#4
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Do not use a re-timed gear, the entire premise of it is a band-aid to fix an already messed up system. It has no effect on chain tension. If you are, then you are compensating for a lower head height, which means severely skewed chain geometry.
Bottom line, the distance between the crankshaft and camwheel is paramount. When that is correct, so will be your chain geometry.
Bottom line, the distance between the crankshaft and camwheel is paramount. When that is correct, so will be your chain geometry.
07-02-2018, 06:27 PM
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I think I would try what you are suggesting. Adjustable timing chain gear will be able to put your timing exactly back to spec.
You will also be probably fine regarding p2v clearance since your math makes sense. If you want to be 100% sure, clay the motor.
What I would check for peace of mind though is how reliable people found the .040" hg to be, no idea if it's used commonly and/or any good.
You will also be probably fine regarding p2v clearance since your math makes sense. If you want to be 100% sure, clay the motor.
What I would check for peace of mind though is how reliable people found the .040" hg to be, no idea if it's used commonly and/or any good.
07-02-2018, 06:50 PM
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Do not use a re-timed gear, the entire premise of it is a band-aid to fix an already messed up system. It has no effect on chain tension. If you are, then you are compensating for a lower head height, which means severely skewed chain geometry.
Bottom line, the distance between the crankshaft and camwheel is paramount. When that is correct, so will be your chain geometry.
Bottom line, the distance between the crankshaft and camwheel is paramount. When that is correct, so will be your chain geometry.
I figured the thicker .040" Cometic head gasket brings the distance between the cam and crank up enough to have only a little timing chain slack which ballade says their adjustable timing gear can do, but yes this all seems like too much of a bandaid fix with too many variables to go wrong.
It's just that I don't know what else I can do if i'm unable to find a head. Do you have any sources at all for a head? I've called every engine parts dealer I could find and had no luck, I'll even buy a non local head if I can be sure it wasn't machined and it'll work.
What would you do in this situation??? Do I have no option other than to buy a new head if I can't find a used one? Any advice to point me in the right direction is much appreciated.
Thanks much
07-03-2018, 02:32 AM
#7
Thanks for chiming in billman. My first choice is to get a used AP1/AP2 head and trash the one I have, but the only ones i found had damage to the combustion chamber and since they weren't local I wasn't sure if the damage was fixable.
I figured the thicker .040" Cometic head gasket brings the distance between the cam and crank up enough to have only a little timing chain slack which ballade says their adjustable timing gear can do, but yes this all seems like too much of a bandaid fix with too many variables to go wrong.
It's just that I don't know what else I can do if i'm unable to find a head. Do you have any sources at all for a head? I've called every engine parts dealer I could find and had no luck, I'll even buy a non local head if I can be sure it wasn't machined and it'll work.
What would you do in this situation??? Do I have no option other than to buy a new head if I can't find a used one? Any advice to point me in the right direction is much appreciated.
Thanks much
I figured the thicker .040" Cometic head gasket brings the distance between the cam and crank up enough to have only a little timing chain slack which ballade says their adjustable timing gear can do, but yes this all seems like too much of a bandaid fix with too many variables to go wrong.
It's just that I don't know what else I can do if i'm unable to find a head. Do you have any sources at all for a head? I've called every engine parts dealer I could find and had no luck, I'll even buy a non local head if I can be sure it wasn't machined and it'll work.
What would you do in this situation??? Do I have no option other than to buy a new head if I can't find a used one? Any advice to point me in the right direction is much appreciated.
Thanks much
I've got a head that was taken off a 40k f20 engine. Ive been keeping it as a spare, but I'd sell it. It has skunk2 dual valve springs and ti retainers. I had it milled flat with .003" taken off...which is standard for any used head.
Last edited by Charper732; 07-03-2018 at 02:36 AM.
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07-03-2018, 04:10 AM
#8
That'd probably be your best bet OP, just swap back in your oem springs and retainers and you'd be all set.
*edit just realized you have an 06, might have to plug the air injection hole with a pre DBW head, though don't quote me on that. I'm sure someone will point out I'm wrong.
*edit just realized you have an 06, might have to plug the air injection hole with a pre DBW head, though don't quote me on that. I'm sure someone will point out I'm wrong.
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07-04-2018, 09:53 AM
#10