Oil Pump Pressure Relief Valve Modification
 

Hello All

I am from the OLD School, “I Like Oil Pressure”

On My NEW 1967 Firebird Sprint, I Noticed that the Oil Pressure was Only 35 PSI.

So I did Something about it.

I looked at the Engine Accessory Unit and Noticed a Hexagon Plug on the rear
of the Unit.

Me Being a Mechanic I came to the Conclusion that it was the Pressure Relief Valve for the OIL PUMP.

I installed Some Cardboard Under the Engine to catch any Oil that Leaked Out, then I Removed the Plug and Spring.

Then I put the Plug in a Lathe, Drilled a Pilot Hole in it, then I drilled it with the
Proper drill for a 3/8 inch SAE Fine Thread Bolt, it had an area with LONG THREADS, Since I Really Didn’t Know how long it should Be Initially.

Anyone can find the Center of that Plug, since it is Hexagon, all you have to do
is put a Straight Edge of ANY KIND, lay it across and Align it with any of the Points of Hexagon and Scribe a Line, do that with All the Points of the Hexagon. Where they All Cross is the Center of the Hexagon. Center Punch where they All Cross, then drill with a Small Hole with a SMALL DRILL of Approx. 1/8 of an Inch, then select the Drill for the 3/8 Inch SAE Bolt Threads that you will be Using. Then I take the Bolt and Machine it on the end so that it will go into the Spring about 1/4 Inch Without Binding up when it is Placed inside the End of the Spring it needs to go into the Pressure Relief Valve Spring “Freely”

I Used a Lathe, you could use a Drill Press and a File to Machine the End of the Bolt, Just be Careful and Make it Concentrically Centered, just do it Slowly until you get the Proper Results. I Made my Bolt about 1 ¼ Inch Long since I really did Not Know Just how long it Really Needed To Be.

MAKE SURE THAT YOU DRILL AND TAP THE HEX PLUG VERY STRAIGHT,
For the 3/8X24 Bolt (The 3/8X24 Tap needs a Q Drill) for the Proper Sized Hole
for the 3/8X24 Inch Tap, that is Why I used a Lathe.

Now take a Cut-off Wheel and Cut a Slot in the Other End of the Bolt so that you can Adjust the Oil Pressure while the Engine is Running using a STUBBY Straight
Screwdriver, De-burr the end of the Bolt so that a 3/8X24 Nut can be threaded on the Bolt Easily. Initially install the Bolt into the Hexagon Cap JUST as Far the Larger Diameter of the Bolt gets Flush with the Inside of the Drilled Interior of the Hex Plug as it was Originally, This will assure that the Engine will Have the Same Oil Pressure as Before the Modification when Started.

Remove the Oil Pressure Sender on the Accessory Drive Unit and Install an “Accurate” Mechanical Oil Pressure Gage, you might install a 45 Degree Brass Fitting Before you install the Gage it will make the Gage easily Readable while Adjusting the Oil Pressure.

Now Start the Engine and Observe the Oil Pressure when Cold and then after the Engine Warms Up to Norman Operating Temperature, the pressures readings should be about the Same.

Now for the Adjustment, with the Engine Running, SLOWLY Turn the Bolt to the
“RIGHT/CLOCKWISE” and watch the Oil Pressure, as you turn the Bolt inward you
will notice that the Oil Pressure Is Increasing “SLOWLY”, Continue until you get to
the Oil Pressure that you would Like to have, I think that 60 PSI is Ideal.

Like I said, “I LIKE OIL PRESSURE” I set Mine at “60 PSI” after the Engine was
at Normal Operating Temperature, It may be Slightly Higher when the Oil is Cold in the Mornings.

Like I have said, “I HAVE NEVER HAD A CAM FAILURE”, I Feel in “Retrospect”
that the 60 PSI Pushed So Much OIL thru THE CAM that all that OIL Could Not Help but to KEEP EVERYTHING WELL LUBRICATED. There are Very Large OIL Drain Back Previsions in the Head and Block to Drain All The Oil Out of the Cylinder Head.

After you have set the Oil Pressure you Desire, tighten down the Nut you installed on the Bolt when you have established the Oil Pressure, You will need 2 COPPER WASHERS that Fit Closely to the Bolt Threads and an Acorn Nut, the First Copper washer is Used between the Hex plug and the first Nut to prevent any Oil Leaks from under the NUT, the Second Copper washer is used between the First Nut and the Acorn Nut to prevent any oil from leaking thru the Threads that can come past the Bolt and the First Nut Threads.

Note” After you have adjusted your Oil Pressure, look at the Adjustment Bolt, Put the Acorn Nut along side the First Nut and Mark the Bolt so that it will fit inside the Acorn Nut, cut it Off and re Cut the Slot for the Screwdriver for any further adjustments.

I took my 1967 Firebird “Sprint” to the Drags just to see what it would do, I Just
happened to pair up with a 1967 Mustang with a 289/271 H.P. and a 4 Speed, we took off together, I Launched at 3000 RPM’s, Shifted at 7000 RPM’s, into 2nd gear and crossed the Finish Line at 7000 RPM’s in 2nd Gear, ½ a Car past him, we got back to the Pits and we were talking, he said that He Could Not Believe that I beat him with a 6 Cylinder, so we agreed to try again, I beat him again by ½ a Car, when we got back to the Pits he started to pack up his things, I asked him where he was Going, his answer was “If I can’t win against you I can’t win against Anyone” and left.

That FIREBIRD was a SCREAMER, I had MORE Fun with that Car than any other
Car I Have Ever Owned at that time in My Life.

NOTE: The 1966 and the 1967 Sprints were Red Lined at 6800 RPM’s, the 1968 and
the 1969 Sprints were Red Lined at 5200 RPM’s, the 66 and 67’s Sprints with AC were Genading the AC Compressor Clutches Because they were Activating and De- Activating their Clutches at 6800 Plus RPM’s., so they Dee-Tuned the 68 and 69’s by putting in weaker Valve springs, restricting RPM’s, You Could Not get AC on them unless you ordered a Higher Ratio Differential Gears so that the Engine would Not Rev/Race like it used to.

Sorry that this got SOOO Long for such a Simple Task.

Hope this Helps with keeping the Ol’e OHC 6 Alive for Many More Years.

Take Care,

Dusty / BMFH

Ive been comfortable just shimming the spring a little.
Never heard of anyone running as high a pressure as you have.
No bearing wash out?

No Bearing Wash Out
 

Hello All

I had NO Problems due to the 60 PSI many engines of that Era had 60 PSI, I ran a High Quality Oil
and a CAN of STP on EVERY OIL CHANGE I still do Today, Except the STP is in a BLUE BOTTLE NOW.
I Truly Believe that the 60 PSI kept that Engine Alive for All thous Hard Miles it had.

As far as Bearing Wash out goes, GM installed very Good Bearings in the Sprints, they Knew that they would be Ran Hard.

That Engine ran Like a Scalded Dog as the Saying Goes.

I was in my early 20's then, I raced stop light to stoplight MANY TIMES,
Never Got a Ticket Thou.

It was SO Much Fun Womping on the V8 Powered Cars of the Day, Of course it was only for Short Burst, they would catch me fast on a longer run.

The Only ones that gave me trouble were the cars Like the Firebird's, Camaro's and Mustang's with the Higher H.P. Engines and the 4 Speed's, although I did beat that 67 Mustang at the Drag's He was Flabbergasted.

I put over 135,000 Miles on that car, I Never had to work on it, Except for the
Time when I Blew off the Exhaust Pipe at the Y Pipe, I ran it HARD, Never Had any Problems other than the Exhaust.

I traded it off for a 1970 and 1/2 Firebird 350/3 speed, I was in the Military and Had to travel a lot, it was getting to that point where Most engines of that Day Started having Problems, I could Not have that while my Family I and were traveling.

I Have Been Kicking Myself for 56 Years for trading it off.

Anyhow, Take Care

Dusty /BMFH

Those were The Days of My Youth

Thought I read someplace that the lash adjusters would pump up.
Sometimes, never, depends on oil restricter??

Hello

My 1967 Firebird Sprint NEVER had a Problem with the Increased Oil Pressure.

I think that I heard Somewhere that you had to Modify the Office on the Oil Restriction Tube, I never had to take my engine apart for any REASON FOR THE TOTAL TIME I OWNED IT.

Take Care,

Dusty / BMFH

First of all, I am not disputing Dusty’s experience with his 67 FB. I own Woodland Motorsports. I sell OHC 6 parts and build these engines. I receive about a call a month where an “engine builder” or “mechanic” has increased the oil pressure above the PMD specification. (26 to 36 @ 2800 rpm) At a minimum, the engine will not run well, or at all. At the worst case, the cam and followers are wiped out due to excessive oil pressure. I spend a lot of time on the phone figuring out what caused their failure. I do not recommend increasing the oil pressure above spec unless one blocks off the internal oil passage and run a regulated external line to the top end. PMD set the pressure by design for a reason.

Hello All

All I Can Say is that it worked for Me,

I Never had ANY Engine Problems the Whole time I owned it.

The Only Problem I Had was Blowing Off the Exhaust Pipe.

Take Care,

Dusty / BMFH