Mazda 1.8l Head tear down-Tech Info
#1
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Mazda 1.8l Head tear down-Tech Info
The basic views
Front
![](https://www.miataturbo.net/attachments/engine-performance-56/41559-mazda-1-8l-head-tear-down-tech-info-dscf6150.jpg?dateline=1335229407)
Rear
![](https://www.miataturbo.net/attachments/engine-performance-56/41560-mazda-1-8l-head-tear-down-tech-info-dscf6149.jpg?dateline=1335229407)
Notice the casting number in the middle to right corner of the casting.
BP4W 2-1
AREA dose not have this head casting listed for in it’s head and block book, but it still may be listed in the CD rom.
Intake side
![](https://www.miataturbo.net/attachments/engine-performance-56/41561-mazda-1-8l-head-tear-down-tech-info-dscf6145.jpg?dateline=1335229407)
Exhaust side
![](https://www.miataturbo.net/attachments/engine-performance-56/41562-mazda-1-8l-head-tear-down-tech-info-dscf6148.jpg?dateline=1335229407)
Top view
![](https://www.miataturbo.net/attachments/engine-performance-56/41563-mazda-1-8l-head-tear-down-tech-info-dscf6147.jpg?dateline=1335229407)
Combustion chamber
![](https://www.miataturbo.net/attachments/engine-performance-56/41564-mazda-1-8l-head-tear-down-tech-info-dscf6144.jpg?dateline=1335229407)
Head thickness Measured from VC rail to head gasket surface is Between 5.270 and 5.272 at four corner points around the head.
Intake valve head measured 1.300
![](https://www.miataturbo.net/attachments/engine-performance-56/41565-mazda-1-8l-head-tear-down-tech-info-dscf6152.jpg?dateline=1335229407)
Exhaust valve head measured 1.103
![](https://www.miataturbo.net/attachments/engine-performance-56/41566-mazda-1-8l-head-tear-down-tech-info-dscf6153.jpg?dateline=1335229407)
The valves were slipped back into the head, and valve tip height was checked.
Intake range 1.792 – 1.799
Exhaust range 1.791 – 1.798
![](https://www.miataturbo.net/attachments/engine-performance-56/41567-mazda-1-8l-head-tear-down-tech-info-dscf6151.jpg?dateline=1335229407)
Next I checked spring installed height on one Intake valve
Measured 1.565 w/out spring seat shim installed
Spring seat shim measures .020 thick
Now to figure out what my seat pressure is.
1.565 - .020 = 1.545 +/- .004
Now setting up the spring tester to 1.545
![](https://www.miataturbo.net/attachments/engine-performance-56/41568-mazda-1-8l-head-tear-down-tech-info-dscf6154.jpg?dateline=1335229407)
Most springs were 35-37 lbs @ 1.545
A low was 33 lbs and a high of 39 lbs
Spring specs.
1.027 OD
1.800 free length
Looking at my SBI Catalog (2007)
Pg 545 Block 12
1.8l 16v “BP”
Spring part number 160-1250 (90-97)
SBI spring spec (Pg 760)
1.831 Free length
46 lbs @ 1.600
But due to the difference in years and no listing for the 99/00 head I am working with.
These springs, are asking for taller installed heights from what I measured by .055
Looking at the supertech springs they as for a much shorter installed height.
http://supertechperformance.com/cata...ection=ivalves
SPRK-MM16D1 56 lbs @ 34.2mm /1.346
That is the loan single spring they list.
It makes me what to think there is miss listings in both SBI and Supertech.
.200 is a lot of shims to be used and no good way to locate it with out the use of special thick spring seats.
The basic views
Front
![](https://www.miataturbo.net/attachments/engine-performance-56/41559-mazda-1-8l-head-tear-down-tech-info-dscf6150.jpg?dateline=1335229407)
Rear
![](https://www.miataturbo.net/attachments/engine-performance-56/41560-mazda-1-8l-head-tear-down-tech-info-dscf6149.jpg?dateline=1335229407)
Notice the casting number in the middle to right corner of the casting.
BP4W 2-1
AREA dose not have this head casting listed for in it’s head and block book, but it still may be listed in the CD rom.
Intake side
![](https://www.miataturbo.net/attachments/engine-performance-56/41561-mazda-1-8l-head-tear-down-tech-info-dscf6145.jpg?dateline=1335229407)
Exhaust side
![](https://www.miataturbo.net/attachments/engine-performance-56/41562-mazda-1-8l-head-tear-down-tech-info-dscf6148.jpg?dateline=1335229407)
Top view
![](https://www.miataturbo.net/attachments/engine-performance-56/41563-mazda-1-8l-head-tear-down-tech-info-dscf6147.jpg?dateline=1335229407)
Combustion chamber
![](https://www.miataturbo.net/attachments/engine-performance-56/41564-mazda-1-8l-head-tear-down-tech-info-dscf6144.jpg?dateline=1335229407)
Head thickness Measured from VC rail to head gasket surface is Between 5.270 and 5.272 at four corner points around the head.
Intake valve head measured 1.300
![](https://www.miataturbo.net/attachments/engine-performance-56/41565-mazda-1-8l-head-tear-down-tech-info-dscf6152.jpg?dateline=1335229407)
Exhaust valve head measured 1.103
![](https://www.miataturbo.net/attachments/engine-performance-56/41566-mazda-1-8l-head-tear-down-tech-info-dscf6153.jpg?dateline=1335229407)
The valves were slipped back into the head, and valve tip height was checked.
Intake range 1.792 – 1.799
Exhaust range 1.791 – 1.798
![](https://www.miataturbo.net/attachments/engine-performance-56/41567-mazda-1-8l-head-tear-down-tech-info-dscf6151.jpg?dateline=1335229407)
Next I checked spring installed height on one Intake valve
Measured 1.565 w/out spring seat shim installed
Spring seat shim measures .020 thick
Now to figure out what my seat pressure is.
1.565 - .020 = 1.545 +/- .004
Now setting up the spring tester to 1.545
![](https://www.miataturbo.net/attachments/engine-performance-56/41568-mazda-1-8l-head-tear-down-tech-info-dscf6154.jpg?dateline=1335229407)
Most springs were 35-37 lbs @ 1.545
A low was 33 lbs and a high of 39 lbs
Spring specs.
1.027 OD
1.800 free length
Looking at my SBI Catalog (2007)
Pg 545 Block 12
1.8l 16v “BP”
Spring part number 160-1250 (90-97)
SBI spring spec (Pg 760)
1.831 Free length
46 lbs @ 1.600
But due to the difference in years and no listing for the 99/00 head I am working with.
These springs, are asking for taller installed heights from what I measured by .055
Looking at the supertech springs they as for a much shorter installed height.
http://supertechperformance.com/cata...ection=ivalves
SPRK-MM16D1 56 lbs @ 34.2mm /1.346
That is the loan single spring they list.
It makes me what to think there is miss listings in both SBI and Supertech.
.200 is a lot of shims to be used and no good way to locate it with out the use of special thick spring seats.
#6
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https://www.miataturbo.net/engine-performance-56/st-ti-retainers-dont-fit-springs-chromoly-options-64087/#7
#7
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ST do use thick extra spring seats.
https://www.miataturbo.net/showthread.php?t=64087#7
https://www.miataturbo.net/showthread.php?t=64087#7
#8
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Join Date: Sep 2009
Location: Edmonton, AB, Canada
Posts: 1,193
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Noob question. So I removed the head and was careful to mark the cam caps. Then I was looking at the head (rotated it) and my lifters fell out, but I did not record from where? Are they specific to each lifter bore because of differing shim size? I would assume they are?
#9
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Noob question. So I removed the head and was careful to mark the cam caps. Then I was looking at the head (rotated it) and my lifters fell out, but I did not record from where? Are they specific to each lifter bore because of differing shim size? I would assume they are?
You have some work ahead of you if you want to puzzle together the same valve lash as before without getting any new shims.
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Zaphod
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