Mazda 1.8l Head tear down-Tech Info
04-23-2012, 09:03 PM
#1
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Mazda 1.8l Head tear down-Tech Info
Mazda 1.8l Head tear down-Tech Info
The basic views
Front
Rear
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
Exhaust side
Top view
Combustion chamber
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
Exhaust valve head measured 1.103
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
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
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
Rear
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
Exhaust side
Top view
Combustion chamber
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
Exhaust valve head measured 1.103
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
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
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.
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04-24-2012, 01:40 AM
#6
https://www.miataturbo.net/engine-performance-56/st-ti-retainers-dont-fit-springs-chromoly-options-64087/#7
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04-24-2012, 02:20 AM
#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
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05-11-2012, 10:41 AM
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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?
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05-11-2012, 10:59 AM
#9
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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05-11-2012, 06:32 PM
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BOGUS!
I SWEAR TO THE FSM THAT IF I EVER FIND OUT WHERE YOU LIVE, I'M GOING TO MAIL YOU A NEW CAMERA!!!!
But thanks for the thread, I appreciate the Miata specific stuff
I SWEAR TO THE FSM THAT IF I EVER FIND OUT WHERE YOU LIVE, I'M GOING TO MAIL YOU A NEW CAMERA!!!!
But thanks for the thread, I appreciate the Miata specific stuff
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