BCR CNC MACHINED MAIN CAPS -
For the serious BB Mopar engine builders out there, BCR products billet
machined main caps.
All BB Dodge motors have a serious problem in the main webbing and cap
area if you use cast iron heads and or make 500 plus horsepower. The heads
have a poorly designed quench area and no matter what you do to modify them
they tend to pre-ignite or detonate the air fuel mixture. This in the long
run tends to crack blocks and cranks then it eventually will break the main
caps themselves. BCR have been building BB Mopars for nearly twenty years
and kept running into this problem. What they found out was if they built a
high HP Mopar with aluminium rods it always lived a longer life than a steel
rod motor. What they found is the rod acted as sort of a dead blow hammer
and took up the shock of the detonation and or in the case of aluminium head
motors the combustion shock and did not transfer it to the mains as badly.
Most people especially street strip guys do not want to run an aluminium
rod due to the duty cycle being so short on them. They found if you use an
aluminium main cap that it does the same thing and you can then run the
steel rods and extend the life and the output ability of all BB Mopars.
Since using aluminium caps the percentage of failure of any of the above
mentioned components went down by at least 80%. As a side note they are
using the same caps on their Super Gas motor now for the past 11 seasons
with no re line bore. The other advantage is they almost eliminate what is
called cap walking. The movement of the caps that can be seen on the bottom
of the caps when removed that looks like a rough surface transferred to the
Along with input from many top engine builders from around North America
and of all places Sweden they redesigned their original caps to create what
they and many others feel is the ultimate main cap. There are others who
build main caps, but beware of the inherent design flaws. Problem with their
caps is they were made out of plate aluminium and they didn't fit very well
and were poorly machined. BCR caps are billet 6061 T6 and are fully CNC
machined on all surfaces. They also had recessed holes for the main studs
and you had to use a special ARP stud kit with a twelve point head. So if
you had a Miloden stud kit with six point heads you had to go and buy
another set because you could not get a socket down in the holes to torque
them. Then you had to modify the rear main seal plate to fit the # 5 cap.
BCR addressed all these issues and they feel have came up with a better
system. These are especially suited for those who are now using the new
Edelbrock aluminium heads as it is easy now to make large Horsepower figures
using them. If you are going to make some big numbers with your stock block
you will need these to ensure a long life out of the stock components. These
caps have now been successfully run in motors making in excess of 700 HP.
These will fit all 383, 400, 413 and 440 stock blocks with two bolt mains.
These require line boring of block when installing.