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.

 

Sooo much good happening.

 

Would be even better using MACRO mode in the camera, with ISO set to 800, and a steady hand!

 

FYI this is stock 99 head

 

Looks like Michael J Fox took the pics

 

ST do use thick extra spring seats.
https://www.miataturbo.net/engine-performance-56/st-ti-retainers-dont-fit-springs-chromoly-options-64087/#7

 

Yep, Supertech singles ship with fatty spring seats.

 

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?

 

The bore size is nothing to worry about, but the valve/lifter/shim combination are unique on all 16.
You have some work ahead of you if you want to puzzle together the same valve lash as before without getting any new shims.

 

i love all of these threads, but lol everytime I see the photos. Keep up the good work. I think the information is great for this site.

 

Haha we need a BogusSVO section of the forum.. just for posting detailed bonerrific pics.

 

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

 

bogus takes pics the way i take videos: :(