----- Original Message -----
Sent: Tuesday, October 02, 2001 =
12:51
PM
Subject: B. Bobs 2.1 main =
bearings
info
Fellow vanagon types and so forth =
mores
With all the talk =
about main
bearings color codes I think I can clear the air on this subject. =
It has
been suggested that the difference in size of the blue verses red is =
.004 ths.
The measurements I have taken show that the difference is .00025 ths.
that turns out to be a 1/4 of .001ths. Why they would =
bother to
make two different bearings sets with so small a =
clearance change
baffles me. The clearance for the main bearings is important and =
hard to
measure I have spent thousands to be able to do this =
accurately
every time. Plastagauge is nice but not the cure for knowing the
clearances of the main and rod bearings and it has let me =
down to
many times.
I have never found =
the case
measurements or the bearing clearances listed for the1.9 or =
2.1
engines and I am not going to offer them today. what I =
will say is
that I have found the need to align bore most 1.9 blocks. =
the reason is
they loose the crush on the bearing over time In layman's terms =
the hole
is to big.
As for the 2.1 block some are fine =
and
some need to be align bored and there is only one way to tell. =
That one
way is with a top of the line bore gauge and a couple of hours
to get the block clean at the mating surface and bolted together. =
I can
say that if the middle bearing web is out of round then it needs to be =
align
bored the other thing you need to know is that the crush is greater on =
the 2.1
main bearings because they are a thinner walled tri metal design
bearings.
The =
clearance for the
main bearings to the crank on the # 3 and # 4 bearings =
is
.002 to 004 ths. as taken from the type 2 Bentley book yes =
its a
different engine but the basic requirements of main bearing =
clearances
are the same and the journals dimensions are also the same.
the # 2 splitshell bearing is not the same in the =
WBX 2.1
engines as the type 4 or the 1.9 engines. the type 2 book says =
the min
clearance is .0012 ths to .0035 ths. As for the WBX 2.1 I would =
not want
any less than 0015 ths on this split bearing to be safe. The # 1 =
bearing
next to the flywheel calls for .0019 to .004 ths I have found =
most
cases with bearings installed to measure close to the high limit =
of new
spec. the wear limit is .0074 ths. WOW
As for the rod =
bearings I like
my rods to have .0015 ths between the rod bearing and the crank
journals the type 2 book lists .0008ths to .0027 ths as the new =
spec this
is for both the 1.6 and the 2.0 air cooled engines.
I =
have recommended not
reusing the 2.1 rods over without having the bolts changed and =
resizing the
big ends of the rods
I just finished =
and test drove
my 84 westy to the transporterfest in brookline MA.
with a stage 3 2.1 big valve =
engine
I'm really pleased with the =
increase in
power. I had some concerned about the injection system but the exhaust =
gas
tests showed everything is a go. I did have to back off the main =
spring for
the air door in the air flow meter to get the mixture set right. The =
mixture
adjustment was much more sensitive than any I have seen I =
think the
big valves are the reason. The flow bench showed a 20% increase =
in air
flow threw the heads at all valve lifts we
tested.
Because of the past shortage of WBX =
main bearings
I used a set of used main bearings in this engine with no problems the =
clearances where right where I wanted them and no oil light =
at hot
idle
my new web page with lots of updates =
and head
flow chart specs for the big valve engines is almost ready and I will =
keep you
all posted
as always all right reserved =
hope this helps
Bob Donalds
Boston Engine Exchange