Ah yes, Mary Mac's head. We're not referring to a town in Newfoundland in this story, we are talking about a very strange crack in the head of Mary MacIsaac's great looking 1979 MGB. Mary and Mike are very new to the MGB experience and they are slowly learning of all the pitfalls that comes with these cars. Unless your paying thousands of dollars for a perfect car, one has to submit to the little gremlins these cars possess. After Mary purchased this car, she had taken it to a local mechanic to have it fixed to the point of being safe and he did a great job. Bushings, brakes and all the little things that were required to pass a safety inspection was done. Reliability and dependability will come later. This is where the British Car Club of Cape Breton comes in. Donnie Peters and I are notorious for saying things like... You must change this or that, you have to check this and that and keep an eye on this or that. Now if members chose to drive on hoping for the best, then good luck. In the case of Mary's head, it was purchase, unknowing, that it had a crack in the head, once discovered, it was time to be fixed.
Before our journey to the British Car Days in Cymbria Prince Edward Island I mentioned to Mary that perhaps it would be a good idea to take the car to my place for a once over to make sure all is well for the long Journey. The car arrived and I went to work. I checked and filled the rearend and transmission, made sure the kingpins were greased, cleaned and adjusted the points and set in a new rotor button. From there I checked the timing, Vacuum advance and finally adjusted a noisy valve. The last thing I did was replace the valve cover gasket because of the oil running down the side of the engine, as you can see.
I checked the dipstick and there was only a smidgen of oil in the crank case..... hummm. As you all know, a little oil can make a big mess so you can just imagine what a mess a lot of oil would be like. Well there was a lot of oil and I sprayed the engine with cleaner and took it for a drive. This car works amazingly well and when I returned, all still appeared to be dry. Great! Off to P.E.I. we all went. For Mary and Mike's car, it was an uneventful trip. Again, Great! In P.E.I. Mike did mention he was down a litre and a half of oil and after he got home he said he was down two and a half litres.... wow! Something is wrong. These cars all leak a little, well most of them anyways so Mike took the little car to a local mechanic for another check up. Head cracked he said but he didn't want the job of changing it. Donnie and I are lucky enough to have a few heads in our possession and we sent one off to our local engine guy for a check and a valve job. All was perfect and we sold it to Mary and as it turns our, Donnie and I installed it as well. Lets get started shall we. Lets replace Mary Mac's Head.
Replacing the head isn't difficult but it is time consuming, so we had to put good ole Mike to work as well, cleaning the liquid gasket off the valve cover. This has to be the strongest gasket maker I have ever seen, we had to use a pry bar under the flimsy valve cover to get it off. Mike spent 3/4 of and hour getting that crap off the valve cover. A little tweaking from pliers and a hammer and the valve cover was back to it's original shape. Slowly and surely everything was remover from the head. No seized nuts or bolts, you gotta love that.
Manifold away from the head, thermostat housing removed, head bolts/nuts off and the valve trail removed. Valve train..... we'll dig in a little deeper into that later but for now the push rods were removed and placed in there proper order in perforated cardboard for accurate replacement later. Last to come off is the pesky heater valve. Usually I disconnect the hose and take this off after the head is off but the bloody clamp was stubborn so we removed the valve while the head was still in place. We told Mike to replace this hose in the near future and he'll replace the clamps as well. The day was warm and sunny and working in Mike's driveway was nice, the abundance of natural light sure helps.
Now for the crack! What an abnormal spot. I have been dealing with these cars for almost 20 years and have never seen a crake here. I have seen a few times a crack between valve seats and even a crack where a head stud runs through the head but never a crack from the sparkplug hole upwards to the valve cove gasket, must be a manufactures flaw. You can see where the mechanic plastered sealant over the crack to stop the leak. Head now removed, time for endless cleaning. The car had a composite head gasket and these tend to leave a fair amount of residue on the contact surfaces, all has to be cleaned before even considering placing the new head on. Here a gasket scraper and a utility knife comes in very handy, as well as a scotch bright pad and some brake cleaner.
The old cracked head is now sitting on the driveway and the new refurbished head is ready to go on. It always pays to do a little homework before putting another head on like cleaning or replacing the thermostat housing studs, chasing the spark plug threads with a tap, plugging the air passages with the proper plugs and most of all..... making sure that the rocker set is the correct one for that particular head. There are two types, inline oil feed rocker block and an offset type. See below.
The head we sold Mary was the offset type and the head we removed was the inline type. Had we not matched the correct rocker set I am sure that there would be oil issues at the tappets and over time there would be a lot of wear on the rocker shaft. Now if you look closely at the second picture at the lower right corner you'll see that someone drilled and tapped a port for the coolant that is used for the choke on the old zenith carbs. So this being a 79, this head isn't the original for the car, someone's been here before. The old zenith crab is gone off this car and I am not sure what the carb that is on this car is from but it works and there is no need for the coolant port on the back of the head but the replacement head had the correct port and the choke bypass hose is there so rather then spent the time correcting and replacing the metal pipe that runs under the carb we just reattached the choke bypass hose.
All new gaskets, fresh antifreeze, head torqued 25 ft lbs first then to 50 ft lbs, the rocker set torqued to 25 ft lbs. The manifold is reconnected and finally the temperature sending unit (that we know is working) was set into place. Mike jumped into the old B and fired it up. A little tweaking and she was ready to hit the road. Well after a good washing that is, as we had the nice white paint covered with greasy finger prints.
The next day Mike, Mary as well as Bob and Judy stopped by my place in their Bs to drop off a fuel pump I had loan Bob. I asked Mike to pop the bonnet for a look and wouldn't you know, dry as a bone. Mary's little car may still need a little attention here and there but I would take this car anywhere.
So there you go. Being a club member does have it's perks. We may not always be available to tackle jobs such as this but the technical support is always there if someone wishes to try this themselves. Never be shy to ask questions, if a regular mechanic mismatched the valve train, the end result could have been bad. Mike and Mary were very generous by paying us for our time and Donnie and I enjoyed a great supper at the Cedar House thanks to them. Thank you.
The number of outings are down this summer as are the stories but rest assured the BCCCB is very active behind the scenes. The planning of the Bert Miller Memorial Fall Colors Tour is finished and the run is only days away and I for one can't wait. Spending a weekend in these great cars with great friends seeing the sight is what being a member of this great little club is all about. Stay tuned... whatever will we be doing next.