Engine Block Fastener
the steps in properly preparing a block for build-up is to clean/chase the
threads in all the various threaded bosses. While making a list of
bottoming taps required to accomplish this little task, I decided to take
some pictures and write up a short article. Here you go!
Starting at the top... This is the
easiest one to remember. All you have are the head bolt/stud holes.
They are all 12mm x 1.75.
Oil pan bolt holes are 6mm x 1.00.
The oil pump mount bosses are 8mm x 1.25, and the main bearing cap bolt
holes are 12mm x 1.75.
Cylinder cover, aux shaft retention plate,
and aux shaft cover are all 6mm x 1.00.
The water pump bolt holes are 8mm x 1.25.
And the two plugs are 3/8" NPT.
Note the block fill... for a little extra
Sorry for the crappy image, but I didn't
have the time or inclination to remove the block form the stand for one
The 4 tapped bell housing to block holes
are 10mm x 1.50.
And again, the two plugs are 3/8" NPT.
See what leaving your block on the deck
will do for/to you? A whole lot of extra cleanup.
the driver's side of the block.
The fuel pump block off plate holes are 8mm
Alternator/Power Steering, motor mount,
distributor hold down, et al. purple are 10mm x 1.50.
The coolant sensor and ?? yellow one are
What is that lower yellow hole for?
Is it just plugged?
finally, the passenger side...
A/C bracket, motor mount, et al. purple
holes are 10mm x 1.50.
The turbo coolant port is 1/4" NPT. In
my case, this port is blocked off by the block fill. Thus, I will just
plug it with a Loctite covered plug.
The turbo oil return is 1/2" NPT.
that's pretty much it... So the bottoming tap list includes a total of 4
6mm x 1.00
8mm x 1.25
10mm x 1.50
12mm x 1.75
They should all be bottoming taps even
though some of the holes are through holes. You need to make sure
you chase the threads as close to the bottom of those blind holes as
Hope this helps,