99/00 1.8 BP Head inspection
33 Attachment(s)
I was shipped a head to inspect and go through.
Not a super fancy build, but just a solid rebuild. The head was packaged well for shipping. This is the inner box Wrapped in plastic https://www.miataturbo.net/attachmen...ine=1356139762 I did not need the cam gears, but they will be cleaned and returned. Out of the plastic. 2 layers of cardboard. https://www.miataturbo.net/attachmen...ine=1356138501 The head looks good to the eyeball, oily, but no sludge build up https://www.miataturbo.net/attachmen...ine=1356138501 The HG surface looks ok, no pitting or heavy rot https://www.miataturbo.net/attachmen...ine=1356138501 Removing the cams https://www.miataturbo.net/attachmen...ine=1356138501 The cam towers look good, no scratches or scoring https://www.miataturbo.net/attachmen...ine=1356138501 Stock springs https://www.miataturbo.net/attachmen...ine=1356138501 Valve springs removed https://www.miataturbo.net/attachmen...ine=1356138501 Pulling the valve stem seals https://www.miataturbo.net/attachmen...ine=1356138501 The old seals https://www.miataturbo.net/attachmen...ine=1356138501 Removing the spring shims https://www.miataturbo.net/attachmen...ine=1356138501 Removing the oil galley plugs https://www.miataturbo.net/attachmen...ine=1356138501 Cleaning the HG surface https://www.miataturbo.net/attachmen...ine=1356138501 The long board barely scratches the surface https://www.miataturbo.net/attachmen...ine=1356138501 The Machinist round edge and the feeler gauge https://www.miataturbo.net/attachmen...ine=1356138501 You can see the gap, This head is warped a fair amount. https://www.miataturbo.net/attachmen...ine=1356138501 A .012 is sticky under the round bar When the head is thremal cleaned, I will straighten at the same time. I would like to see less than .005 once done. https://www.miataturbo.net/attachmen...ine=1356138501 Checking the cam towers for distortion https://www.miataturbo.net/attachmen...ine=1356138501 No nocticable rock in the intake towers, minimal in the exhaust. Ill check it again after it is straigten More to come..... |
Thanks. I'm about to have this done. :cry:
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Originally Posted by hustler
(Post 961678)
Thanks. I'm about to have this done. :cry:
Its not all that bad. It is rather simple. |
I have a head sitting in the shop that's warped .012" that's labeled "Junk" and "Parts head". Hopefully the buyer knew it was that bad before he bought it.
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Originally Posted by BogusSVO
(Post 961677)
[snip]
A .012 is sticky under the round bar When the head is thremal cleaned, I will straighten at the same time. I would like to see less than .005 once done. [snip] No nocticable rock in the intake towers, minimal in the exhaust. Ill check it again after it is straigten [snip] Glad you're back Bogus :bigtu: |
Yes if you mill a head .012 it will close up the combustion chambers.
The general rule of thumb is for every .007 milled the combustion chamber looses 1cc So time this head is milled .012 -.014 it would be 2cc smaller. When the head is set to be straightened, Ill post up. I have salvaged heads that have had as much as .030-.035 warp across the bottom and had .005 or so cam tower warp. Alot shops will not straighten a head, either they do not know how, or they just do not want to. It takes some time, and sometimes you will not get all the warp out the first time. Just a little more machine shop voodoo to show you all is why Ill straighten this one, instead of just grabbing a core to do. |
Gotcha, makes more sense now. I could see why most shops would not want to touch a DOHC head with a twist in it. I know my guy took a hell of a cut on the FE D2TE heads in my truck, but that thing needs all the compression it can get so I wasn't really worried about it.
Out of curiosity, what's the factory max recommended cut on one of these heads, and how much does it take before you start screwing with timing? |
Originally Posted by EO2K
(Post 961693)
Glad you're back Bogus :bigtu:
and decent quality pictures makes it even better :) |
Originally Posted by EO2K
(Post 961702)
Gotcha, makes more sense now. I could see why most shops would not want to touch a DOHC head with a twist in it. I know my guy took a hell of a cut on the FE D2TE heads in my truck, but that thing needs all the compression it can get so I wasn't really worried about it.
Out of curiosity, what's the factory max recommended cut on one of these heads, and how much does it take before you start screwing with timing? The min thickness on a BP engine? Humm Ill have to check my AREA spec book. But most the time it is about .015. When will the timing be effected, That starts the first time the head is milled, but on a DOHC it is not as noticable as a SOHC Anytime the C2C of cams to crank is changed the mechicanical timing is changed.
Originally Posted by NiklasFalk
(Post 961752)
+1
and decent quality pictures makes it even better :) |
2 Attachment(s)
Thanks again Dale. I just finished torquing down the rods when you called.
https://www.miataturbo.net/attachmen...ine=1356195442 Going to try to get engine buttoned back up and in car by tonight. |
Did you balance the rotating assembly? or at the at least the new rods and pistons?
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I would like to know more about the head fix. I have a warped 94 1.8L head and figured it was junk.
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I would like to see your method for removing the valves on a miata head. That's one of the few things I'm unable to do in my own garage.
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2 Attachment(s)
Originally Posted by BogusSVO
(Post 961842)
Did you balance the rotating assembly? or at the at least the new rods and pistons?
https://www.miataturbo.net/attachmen...ine=1356240045 |
Originally Posted by EO2K
(Post 961702)
Out of curiosity, what's the factory max recommended cut on one of these heads, and how much does it take before you start screwing with timing?
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I think I have a man-crush on BogusSVO. This gives me more motivation to get enrolled at The Most Respected Name in Motorsports Education - School of Automotive Machinists.
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Hmm, I'll be interested to see if you use a variation of the oven bake method or the torch method to straighten the head.
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Originally Posted by slmhofy
(Post 961923)
Yes. I made a ghetto make shift fixture of the tool you have and got everything within a gram with my on sale $12 Harbor Freight scale. Highspeed grinder and belt sander took care of the rest.
Originally Posted by Savington
(Post 961937)
IIRC, the FSM says max cut on the head is .012 but people exceed that all the time. EP motors are cut .050", IIRC. You start screwing with the timing immediately, but you can correct for that with cam gears (or one cam gear and VVT tuning).
Adjustable cam gears... what a great invention!
Originally Posted by czubaka
(Post 961940)
I think I have a man-crush on BogusSVO. This gives me more motivation to get enrolled at The Most Respected Name in Motorsports Education - School of Automotive Machinists.
Originally Posted by kaisersoze
(Post 961948)
Hmm, I'll be interested to see if you use a variation of the oven bake method or the torch method to straighten the head.
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Head straighting set up
10 Attachment(s)
Well a few have shown intrest on how this will be done.
What is needed. A steel plate, with properly placed holes. A torque wrench, and socket Pull bolts Head bolt washers Body washers Anti-sieze Shim stock Attachment 62841 Place head bolt washers on the pull pins Attachment 62842 Place the pull pins through the head bolt holes and through the steel plate. Attachment 62845 Now coat the shim stock with anti-sieze and place under the head. The anti-size will give the head some lube to slip on as the head straightens out. Attachment 62843 Now place the washers on the pull pins, and snug the nuts down. Roll the head and fixture over and torque the pull pins. Attachment 62844 The head and plate fixture will be placed in an oven for several hours, the temp will be watched closely, to bring it up to temp slowly, then stablized for a couple hours, then temp will be dropped slowly untill back to room temp. |
Just curious and I'm assuming the answer is no. But would it make much of a difference to to have the cams torqued in when the head is cooked?
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