Comments from Paddy's Engine Builder - 1380cc Engine - Torque Gain

From - Bill Gilcrease - Mincomp's Corner (May 1997)

No racing to talk about at the moment, so let me talk a bit about 1380cc motors.

Engine bayI am deluged with “what’s the deal with 1380s?” or “Why?” Well the answer starts out quite simply, “bigger is better,” referring to more cubic centimeters (CCs) or in big car terms cubic inches. The basic fact is that with all things equal except fore bore size a 1380 will have about 15 HP more than a 1275. But the real advantage is the torque gain. (Torque is what pins your head back of the seat when you accelerate.) Once, again, all other things being equal a 1380 can give up to 25ft. lbs. more torque than a 1275. The real significance to the increased torque is that it allows your beloved Mini to become a rather comfortable freeway cruiser by lowering the RPM that are required at any given speed.

Building a successful 1380 is not just as simple as boring it for the larger pistons. In most every instance I have found that a cam designed for the 1275 just does not work very well in a 1380. Now I can sit here and wait for miscellaneous hate mail/Faxes/phone calls about that statement or the next one I’m about to make. In 1991 or 1992 I had one motor on my dyno playing with this cam thing and in the end I came up with a spec. that turned that 1380 to life. Up to that point I must admit that I never could see what all the hype was about but after I was done with this project I was a believer, at least in the 1380’s I was building.

I guess the whole reason I got into writing about the 1380 camshaft thing was because I just finished up a job here at the shop that was a duplicate of several that I do over a year’s span. People call me or bring in their prize 1380 that they or someone else built for them stating “I expected a lot more.” Well I advised them on what I believe the fix to be, and why.

The bottom line here is that every time I have done this cam change the customer has left smiling because he has gotten what he originally expected, and quite often more than he hoped for!


Previous Blog Post: Stages of Tune

Paddy Gets New Whiskers! Classic Mini Mk 1 Trim

 Below are some before and after shots of Paddy's front end trim                                            

           IMG_1039            IMG_1570











Before Whisker Treatment


After Whiskers . . . 



Here are a couple of installation comments from the UK Mini Forum:




The moustache? From memory, it's also secured with a handful of self tapping screws along its bottom/inner edge. The final dress-up are the moustache whiskers. Those are short chrome extensions that go on the ends of the moustache. To secure those is tricky.

The whiskers are secured with clips that are supposed to get screwed to the front panel. Fitting them as the factory intended is a pain. Instead, I modified the clips by soldering a nut to them, marked and drilled through-holes in the front panel and secured the clips by inserting machine screws from the back (inside of the front panel). This allows the clips to stay with the whisker (not on the car) when removed, and it makes it much easier to install the whiskers without damaging the paint.


Next, had to work out how to install whiskers, they took about an hour to put them on, a little fiddly:

1. Take off front flares
2. work out height of whiskers
3. rivet clips to body (tip I put a washer behind the clip so that they were not so hard up against the body)
4. spray silicone spray on clips, body and whiskers
5. slide whiskers on, over the end of the grill surround



Paddy At Classic Minis United (CMU) 54 - Wytheville, AV

Last year the Classic Minis United (CMU) group chose Wytheville, VA as the base for the 3 day driving adventure - Mini 54. It was located in the foothills of the Blue Ridge Mountains.

Wytheville is known as "The Hub of Southwest Virginia" and "the Crossroads of the Blue Ridge". As with all CMU events, we like to drive, and that's what we did. We had drives each of the three days with plenty of stops and things to see. Add in the nighttime activities, scavenger hunt, live Bluegrass band, swap meet, and we had the most amazing classic Mini event in North America!

Below are a few pictures of Paddy during the event -



Paddy - Mini 54 Backroad VA

Paddy - Mini 54 2013


Mini 54 Rear View


Paddy The Snake 2013


Paddy 37 Front


Paddy 37 Profile

Rust and Paint Repair to Classic Mini Door

Paddy is being treated to a week at Bob Zook's Auto Body for some minor rust and paint repair to the driver side door.  From the time that I brought Paddy home, there had been a line of paint "bubble" at the very top edge of the door where the stainless window trim meets the painted surface.  

I originally thought that it might just be a buildup of paint, but after returning from Mini 54 I notice that the bubbles were cracked and there was some rust underneath.  Yikes!  I didn't want THAT to continue.

One body shop thought it might be from improper paint preparation from a prior re-spray and thought I might be opening a can-o-worms if I tried to paint just the affected area.  I didn't agree and decided to take it to Zook's.

Paddy was welcomed into the "Zook Family" of car restorers and they agreed with me that the issue was not paint prep, but rust starting from where the window meets the trim.  We thought we could just pop off the trim, sand, and paint . . . but as the pictures show, all the hardware needed to come off along with the entire door.

I stopped out to check on the progress and the door is sanded and primed.  Looks like I'll probably get him back nest week in time to tuck him in for the Winter.

Photo 2 Photo 1

DIY - Classic Mini Oil Relief Valve - Series A+ Engine - Part 1

My classic Mini [Paddy] is fitted with a  low mileage Series-A+ engine that was modified in California.  (Bill Gilcrease of Mincomp Racing rebuilt the existing engine into a high-performance 1380cc unit.)  

This Spring I took  Paddy up to Vintage Sports Car  for a head gasket replacement and tune-up. Vintage Sports Car Inc. is a division of Historic Race Car, LLC in Woodstock, IL.   In talking with the shop owner, Yves Boode,  I was advised to address the higher than normal oil pressure.     Yves said that running oil pressure at a level higher than necessary only resulted in wasted horsepower as the pump was working harder than it needed to.

OilplungThis post is to record some of my online research into what exactly the Oil Pressure Relief Valve does in a Series-A engine and some basic thoughts on how to correct low and high oil pressure.

The following comments are from Mini owners and online resource materials.  I've tried to link and give credit to each of the comments and graphics.

What Effects Oil Pressure?

The pressure you achieve will depend on several factors:

  • Oil Grade - A Mini should have a good quality 20w50 oil
  • RPM. The higher the RPM the higher the pressure will be
  • Oil Temperature - The higher the oil temp. the lower the pressure. Ideal oil temp is around the 85 deg C to 95 deg C region
  • Condition - The condition of the oil pump and crankshaft bearings.



What Effect Does the Oil Relief Valve Have On Oil Pressure?

The oil pressure increases with RPM, a faster turning pump squeezing oil through the same size gaps. A relief valve bleeds off the excess oil when it gets to a certain pressure, which reduces the back pressure on the pump saving power. An adjustable valve lets you fine tune the relief pressure so you can set it as low as practical to save the most power.



Where IS the Oil Relief Value on a Classic Mini?

The oil pressure relief valve is located under the hexagonal domed nut on the front face of the cylinder block, directly above the starter motor . If the valve plunger is not seating correctly, or the spring is weak, this will prevent the correct oil pressure (60 psi/4.2 kg/cm2) being maintained in the engine lubrication system.  

Image Link -

  • To examine the valve, unscrew the domes nut with its folded copper washer and withdraw the coil spring and valve plunger. 
  • Check the length of the spring. This should be 2.86 in (72.64 mm). 
  • Inspect the face of the valve plunger for pitting, and that the valve is seating correctly.
  • Renew the valve if necessary.

If the valve is only lightly pitted, it can be lapped in on its seating using metal polish. A wooden dowel of appropriate diameter pushed into the open end of the plunger can be used to rotate it while lapping it in. Clean all traces of polish from the valve and seating when this operation is completed. Refit the components of the valve assembly in the reverse order of removing. 


How Does the Oil Relief Valve Work?

Here's a quick and very rough paint sketch to show you what's going on with the Pressure Relief Valve system.


  • The red passages are all unfiltered oil, the diagonal passage at the top leads to the port where oil leaves the block to enter the tube and travels to the filter head. 
  • The green circle is a cross section of the main oil gallery and contains filtered oil. 
  • The insert (shown in black) allows the gallery to cross the PRV tapping without the two parts of the oil system mixing, which it needs to do because the feed from the gallery to the rear main and cam bearings is on the outside of the PRV port. 
  • The ball or thimble then rests against the seat inside the insert, until pressure pushes it open against the spring and allows oil to flow back down to the sump. 


Part 2 of this DIY series will address my specific issue of oil pressure that is TOO HIGH when motoring along at 3000 RPM.   With the help of Yves Boode, Vintage Sports Car, in Woodstock, IL, I've got a step-by-step process to check the pressure relief value components that may be causing the pressure to remain too high.  


Additional Resources: