The following is an email message
that Dave Dodge sent to me explaining the top end oiling problem and the possible
solutions to it.
Nice to meet you and it is my pleasure to help.
Through the many years of working with the Honda V-4 engine, the main problems causing cam
and rocker arm failure is the lack of a good oil supply and also the way the valve
adjustments are done. Since the beginning Honda has made many upgrades to the materials,
hardness, etc., but the problem can still occur at any time.
The stock top-end oiling system is low pressure, low volume and unfiltered. One thing that
most people overlook is that the top-end is getting it's oil supply from the low pressure
side of the oil pump, and to build the pressure to an acceptable level the oil passes
through a nozzle with an .080" hole which equals less than 25% of the ID of the metal
hoses it feeds. If the oil is not changed regularly, debris can be passed through to the
heads which can cause cam journal grooving. Also, when the engine is at idle the pressure
can sometimes drop below 8 psi meaning that sustained idle time can cause wear that
progressively gets worse. Next is valve adjustment. Because the stock oil system feeds no
substantial volume, tight valves can actually wipe the oil from the lobes and rocker
surfaces causing even more wear or cam pitting. This is why Honda increased the clearance
spec from .004" to .006". When the engine is at running temp., valve clearance
is reduced as much as .003" from part expansion. The entire surface of the cam only
gets lubricated at the point on the heel of the cam where you have clearance.
There are even occurrences where an engine and cams will be fine for 30K or more miles
then all of the sudden cams fail. This can be caused by the last valve adjustment, or a
weakened oil pump. An oil system that is barely good enough to begin with can cause
problems as the pump loses it's full pressure from wear.
Now with all that out of the way, the cure would be to install a top-end oil system.
Whether it is an adapter style or main galley tap, you will be using a high pressure, high
volume source of filtered oil. Yes there are many versions of do-it-yourself mods and
other companies that produce kits. I have been making and selling these kits since 1982,
and offer 3 main styles including the ones you mention. My kits are the only ones
available that actually increase idle oil pressure after installation. Even though you do
not race, you benefit from my years of beating on these engines which leads to products
that far exceed your needs.
I offer three styles of kits which are all designed to provide the best function and fit,
at the lowest possible price.do-it-yourselfer.
The kit I am selling the most of right now is my bolt-on filter adapter style oil mod kit.
It is similar to the Holeshot unit, but I have made some important improvements, such as,
adding an o-ring around the center bolt for better pressure retention and no chance of
un-filtered oil entering the main galley. We also use metered feed lines with angled banjo
hose ends to better clear the coolant pipes. This kit sells for $249.00. This kit is
considered a bolt-on, but does require radiator removal to access the top-end hose
Option 2 is my original DRP drill and tap style. This kit requires you to drill and tap an
1/8 NPT hole in your engine cases for the main supply. The feed supply hose is size #4, to
a special made junction block that splits into 2 size #3 hoses and uses the same angled
banjo ends as above. This kit sells for $159.00. This is the least expensive, but the
hardest to install and requires some long tooling to complete the job. The exhaust system
must also be removed in addition to the carbs for full access.
There is also a style known as the "15-Minute" style oil mod. This option uses
the same filter adapter as option 1, but has one line feeding the stock metal lines. I
supply a special double banjo bolt and fitting to replace the stock single bolt at the
transmission. This kit sells for $199.00. This kit is the easiest to install, but there is
one variable to consider, that being the stock metal lines and banjo bolts. One other
design flaw we found long ago was that the banjo bolts that secure the stock metal lines
to the heads have triangular shanks on them. Depending on how these bolts are torqued,
there is a possibility of them blocking the oil passage hole in the oil line where it
enters the head. The cure would be to turn these bolts down (which I do) to ensure that
there is no blockage. Options 1 and 2 use replacement braided feed hoses with recessed
banjos to eliminate the potential problem.
Okay, how confused are you now? I spent some time writing this because my new website will
include all this type of info, so I will use it later.
Here is my complete company info:
Dodge Racing Products
attn: Dave Dodge
16503 Glenfurness Drive
Huntersville, NC 28078
Tel: (704) 892-7961