1UZFE Main Studs Vs. 3UZFE Main Bolts
When I was doing GS430 Block Vs.
LS400 Block (3UZ vs. 1UZ) I totally over looked the
differences between the two engines. My initial thought
was they are all the same. However, assume they are the
same between the two engines is an understatement. In fact
the two blocks have major differences. In this article I
will focus on the 6 bolt main. Although the thread and
pitch are the same, but that is as far as it goes. The 1UZ
has 4 main studs and two side bolts in each main cap.
There are a total of 5 main caps. The 3UZFE on the other
hand have all main bolts. The main bolts are the same size
in the 3UZ. However, in 1UZ, the length is different
between the outer and the inner studs. Lets look at some
The first picture is the overview of the two main fasteners.
On the left are the 1UZ and on the right are the 3UZ. You
notice the different in stud length on the left. On the
right, the bolts are the same length. The only thing both
engines share one common bolt is the side bolt.
Here is a close up of the 1UZFE studs. They are both 10mm
with 1.25 pitch. The inner stud is about .455" longer then
the outer stud.
Here are some pictures of the 3UZ Main bolts. The main bolts
are all the same length. The exact length 3UZ bolts are
Here is an interesting picture. On the left is the standard
1UZ head studs, in the center is an ARP Main Stud and on the
right is the 3UZ main bolt. You can see the size
difference between the two fasteners. I would prefer the
middle fastener if you a strong bottom.
Here is a closer look at those fasteners. The diameter of
both standard 1UZ and 3UZ fasteners is .293" and the ARP Main
Stud is .393". The ARP Main Stud shaft is about 34.1% larger
Here is something very interesting and you might not find this on
the net about our engine block. If you look at the picture
below you will noticed the two holes for the studs have
different depth. The inner hole is about .145" deeper then
the out hole.
Here is a picture of the 4 bolt main from a GS430
Here is a picture of the oem side bolt and the stainless steel ARP
Here is a picture of the oem side bolt.
Here is a picture of the ARP Side bolt
The picture below is a comparison between stock and upgraded side
The pictures below are a close up of the arp main studs.
|Bolt/Stud Length (Outer)
|Bolt/Stud Length (Inner)
|Thread Length (Outer)
|Thread Length (Inner)
|Thread and Pitch
||10mm @ 1.50
||10mm @ 1.50
|Engine Hole - Sink (Outer)
|Engine Hole - Sink (Inner)
What does all these mean? Stock Vs. Stock, the 1UZ has
better fasteners. Its is know by high performance arena
that studs are stronger then bolts. Therefore, its wise to
upgrade your main bolts to main studs. I have cross
referenced some ARP Main Studs for the Lexus V8. The ARP
Main Studs are far superior than the standard 1UZFE main studs.
contact me for more information.
Other articles of interest:
Lexus 3UZFE rod vs. Lexus 1UZFE rod
GS430 Piston Vs. LS400 Piston (3UZ vs.
GS430 Block Vs. LS400 Block (3UZ vs.
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