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Mazda 1.8l Head tear down-Tech Info

Old 02-08-2013, 10:36 AM
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Wink Mazda 1.8l Head tear down-Tech Info

Mazda 1.8l Head tear down-Tech Info

The basic views

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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 its head and block book, but it still may be listed in the CD rom.

Intake side
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Exhaust side
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Top view

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Combustion chamber
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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

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Exhaust valve head measured 1.103
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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

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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
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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.

Catalog -

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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