MGB Alloy Cylinder Head

The MGB has spent too much of the year in some sort of triage.  I can't complain too much.  Other than the usual small quirks, tune-ups and maintenance, there has been minimal amount of work done on the car in the last several years.  It was due for a good once over on a few key systems.

The actual issues started in late 2012.  After the car was parked for the year in the fall, I noticed a small amount of fluid from near the left rear tire.  A quick investigation revealed brake fluid and a subsequent closer look on a rare warm winter day showed that the wheel cylinder was leaking prolifically.
I have rebuilt the rear brake cylinders a few times and there was some pitting.  Generally, pitting outside of the immediate area of the rubber seal is OK, but I decided not to rebuild again this time.  While one rear steel line had been replaced several years ago, the other had not and while removing the brake cylinder, it broke.
After ordering everything needed from Moss Motors, the car was on the road in time for good weather in the spring.  Unfortunately, it wasn't as ready as I had hoped.  The rear brakes were running hot.  Since I tend to snug up adjusters too much, I backed them off figuring that was the end of the issue.  After a few more drives, it was obvious something else was wrong.  At first I was afraid it was the silly little thin pin inside the master cylinder that is designed to draw the rear master cylinder piston forward but because I was able to get some fluid out of the bleeders, I ruled that out.
I never did get the satisfaction of finding out what was the root cause of the sticking rear brakes, but either gunk in the system or internal break-down of the rear flexible brake hose (between the body and rear axle) was impeding the flow of fluid.  Foot force on the brake pedal was sufficient to send pressure to the rear brakes, but there was insufficient force from the springs to push it back and the brakes stayed slightly engaged.  Unfortunately, the heat degraded the rubber seals in the brakes and I ended up rebuilding the almost new cylinders.
Because every issue required troubleshooting, ordering and waiting for parts followed by finding time to repair, this took much of the spring and early summer season to sort out.

The title of the post has nothing to do with brakes...don't worry, I'm getting to that.

With the brakes sorted out, the car decided to run poorly.
MGB cylinder heads crack.  They crack a lot.  I have about 6 B-series cylinder heads and they are all cracked.  The only saving grace for the poor design around the #2 and #3 overheated exhaust valves sitting next to each other is that MGBs can also run rather well with moderately cracked heads.  As long as the cracks don't cause valves to get pulled into the cylinders or valves to burn, small cracks can be tolerated.
On the current MGB, I knew the head was cracked and the engine tended to run on three cylinders for a few seconds after a cold start.  I knew this was likely due to the crack extended between the combustion chamber and the water jacket, but after those few seconds, the car ran well, there was no white smoke and all four cylinders had decent compression.

Around the time the brakes were sorted out, the cylinder head gave up the ghost.  The car ran on 3 cylinders intermittently regardless of running temperature.  And other telltale signs of water mixing with combustion were present.
What to do?  I had four options:

1. Put on another cracked head from my stash.  I really didn't want to do this.  To be honest, my current stash of MGB parts needs a going through and the ones I know I'll never use need to go to the scrap yard.  This probably should include most of my cylinder heads.
2. Look for a buy a decent used head.  Let me say this again, MGB cylinder heads cracked.  As these cars continue to age, the cast iron is becoming more brittle.  The later heads are capable of handling non-leaded gas, but they also tend to be weaker.
3. Buy a new cast iron head.  MGB cylinder heads crack.  One would hope that newer castings are going to last longer.  And, new castings typically have hardened seats and bronze silicon valve guides.
4. Buy one of the new fangled alloy cylinder heads.

3 and 4 were both viable options.  While an alloy head won't crack, there is the real issue of corrosion from dissimilar metals and the fact that aluminum cylinder heads are known to have to potential to warp.  

New cast iron heads can be found from around $800 to around $1200.  Researching suggests there are a few manufacturers and they are often sold replaceably with each other.  Message boards and blog posting suggest these are pretty good heads, although still prone to cracking on overheating.  Surprisingly, I was having a hard time finding good rebuilt used cylinder heads for less from reputable sources.

New alloy cylinder heads can be purchased from about $900 to a whopping $2500.  Research suggests that there are two manufacturers of these heads.  The units sourced form the UK are crazy expensive but there is a lot of bragging about the few horse power they give.  I wasn't interested in horse power as the MGB is just a daily nice summer day driver.  The other source is Pierce Manifolds in California.  Pierce using offshore castings for the heads.  As with any supplier, offshore castings can be great or mediocre.  Message board postings from a few years ago suggest a bad lot of castings, or possibly it was just people being pickier than can be justified.  It appears Pierce supplies cylinder heads for third party sales by several very reputable British car parts companies lending credibility to the product.  As an aside, the 5-speed conversion also appears be made by Pierce.  The third party suppliers tend to mark up from Pierce's advertised price by 40% - that says something as well.

Ultimately, I decided to try something new and go with the alloy cylinder head directly from Pierce.  The most prolific complaints about the alloy cylinder heads seem to be that they are not ported and polished to race specifications.  I just wanted a head that was reliable and the alloy will definitely transmit heat more efficiently than cast iron.

I ordered the head as well as a Payen head gasket kit.  It arrived well packaged and I was surprised how light it actually was.  There was some residue and metal shavings in the head, but generous use of solvent and compressed air cleaned the head quickly.  

The old head was removed form the engine.  Surprisingly, given the level of water contamination I could not see the water jacket crack.  Usually, a bit of cleaning can work to show MGB cylinder head cracks in the usual spots.  Not unsurprisingly, the #3 cylinder was "steam-cleaned" due to the water introduction from the crack.

The new alloy cylinder head was installed after generously lubing the cylinder head studs to help stop corrosion.  Although, the MGB engine probably oozes enough oil to make this superfluous.  Everything bolted up as it should except the manifold.  Since the alloy is a little weaker than the cast iron, all threads are tapped coarse where as the cast iron has fine threads for the intake/exhaust studs.  New coarse/fine studs were sourced and the installation completed.  Everything bolted up as it should have.  One nice benefit was that the exhaust which had loosed considerably of the years was retightened with new exhaust donuts resulting in a much quieter drive.

Initial driving was good.  Seat of the pants driving suggests power level was similar enough to the old head to be ignored.  There were not issues with valve clearance with the alloy head and retorqueing (without first loosening the head nuts) resulted in minimal movement.  Sometime next spring, I'll slightly loosen each nut and retorque, one at a time.  Payen doesn't recommend this, but Pierce says heads should be retorqued cold.  

One scary thing is the spark plug holes are very tight.  Judicious use of antisieze on the spark plug threads and around the base of the plug body will hopefully allow removal.  I suspect after a few times, removal will get easier.

The only issue I had was engine heat.  The car ran warmer than it used to.  Checking, double checking and triple checking the timing and carbs could find no driveability cause.  I've always had questions on the radiator on this car, I know the baffle in the upper tank is loose and I've always suspected it was restricting flow.  I also question whether all the down tubes were free and clear.

As I didn't want to ruin the head or test any theories on the aluminum alloy warping, I decided to invest in a new radiator.  The local reputable radiator shop wanted $400 to recore the existing radiator with a very high quality core.  This was probably the best option, but for that price, I could get one of the wizz bang Wizard Cooling horizontal-flow aluminum racing radiators.  I was able to find another radiator from a semi-local shop for less than $200.  For that price, I was willing to try - especially since it was listed as "made as the original in the UK."  Apparently that does not mean made in the UK since the sticker on the unit once it arrived proudly announced made it Turkey.  

In my experience, Turkish manufacturing is all or nothing.  Either it is great, or terrible with very little inbetween.  The radiator seemed well-made despite having a slight reduction in cooling fins.  

I held on to my existing radiator since I may have it recored some day, but the new Turkish radiator dropped right in and installed quickly.  Initially, the car still ran warm, but after a few drives, it is now running at a normal temperature.  I suspect a combination of removing all the air pockets as well as having the new head wear in has helped.

(Note the patented Faygo coolant recovery system - it works better than you might think and is cheaply replaced when it gets dirty)

There has been several hundred miles on the car so far since this adventure was completed.  The car runs as good as it has since I got it.  The temperature gauge will continue to be carefully monitored but I hope that the considerable investment this year will result in many more years with minimal work.

In calculus, there is a principle of indefinite integrals where one can take a line from a mathematical formula and spin it around an axis and then calculate the surface area and volume of the resultant solid.  For some equations, it is possible to have infinite surface area but a finite volume.  I often see older cars as comparable.  A car has a finite volume, a box can be drawn around the car where the car is completely inside.  However, the ability for things to break within that finite volume seems to be infinite.  

Should the Car-ma dictate, I will be back at work with greasy hands soon.

Update 8-June-2014:
After many miles on the car now with the new head and radiator, the car runs as good as it has in the last 20 years and there does not seem to be any tendency to run hot or overheat.  I'm very pleased with the performance of both the aluminum alloy cylinder head and the new Turkish radiator.
As an aside, I also had to change the water pump.  No doubt the (albeit small) leak from the existing pump was due to gunk getting stirred up by the head and radiator swap.  Two bolts were severely rusted in place and broke during the swap - this required the housing to need to be cracked around the bolts to get the old pump off.  The only hiccup here was that new bolts purchased form Moss Motors were coarse threaded - for a company that does so many things well, these little continuing problems from Moss are absolutely infuriating when staring at a disassembled car.  Luckily I was able to locate two bolts in my stash to replace these.
Safety Fast!