Special thanks to Rick, Roland, Dave, Ed Key, David Godfrey, Alan Slocum at the Merkurencyclopedia.com, Ryan Mattson at the Merkurdesktop.com and all the Merkur Owners out there who gave me most of this information.
(These people are known for driving sleepers.)
Porting a head is a lot of work and is very hard on the wrists. You need a good electric drill. I use a 1.5 HP drill that broke the wrist of the former user. I also use a die grinder for the finish work. Carbide burr's @$18.00 each, grinding stones @$6.00 each and emery cloth. Some people prefer Dremel type tools. This will make the job take a lot longer.
A lot of these parts fall into the category of "Well while you're at it you might as well put in a new one of these too." For porting you'll need a spare head gasket, spare intake and exhaust gasket and spare valves. To recondition the head you'll need a new cam seal, cam bearings, valve seals, valve keepers, valve springs, new lifters, valve cover gasket, new timing belt, new heavy duty tensioner, new valves or recondition the old ones, and the tool for installing new cam bearings. (And while the top end is off you might as well do the rings and main bearings.) You might as well rebuild the bottom end when you do the head, really easy once you have the head off.
The best way to clean the head is to have it baked. The head is taken to 600 degrees which burns away any deposits. This also helps to relieves any stress in the metal. Have the machine shop do the rough cuts for the valve seat inserts and the rough cut in the exhaust ports outlined below. Make sure they measure the original seat height and match it when putting in the new inserts so that you can set up the valve lash later on. They will need to deck the head and both manifold faces to get them perfectly flat. Remember that you will be retarding the cam as you take surface material off of it. Each .100 of an inch cut will equal about 2.5 degrees. I use Automotive Engineering Technologies. They cleaned, magnafluxed and decked the head. They also unshrouded and reconditioned the valves and did the inserts and a three angle valve job. They also dressed the valve tips perfectly. Have them put the inserts in after you are done all your porting. It is almost as cheap to buy a head from Esslinger,Powerheads.com or one of the other companies after you add it all up.
This is the combustion chamber before any porting has been done. The chamber is very rough. The valves have been unshrouded. I had them cut the head to enlarge the area next to the valves. Make sure they do not go too far and contact the loading area of the head gasket. The head has been decked flat with a minimum of the head surface removed. As you remove the head surface you increase the compression ratio. This is not what you want on a turbo engine.
Notice the difference in size between the combustion chamber in the first and second pictures. This is before and after porting.
The combustion chamber after porting. I unshrouded the valves as much as possible. I am using the stock valves. The exhausts are made of inconel from the factory. I like these better than stainless aftermarket valves. I removed the ridge in the valve face to help the flow and to avoid hot spots that cause detonation. The exhaust valve required a lot of grinding to remove this ridge. Also remove the sharp edge in the head itself. You can see how close the spare cylinder head gasket (Detroit) is to the the combustion chamber near the valves. This will lead to higher velocities than with the big valves and unshrouding. I removed the most material in the area that goes from the spark plug to the exhaust port. I want the easiest path for the exhaust to leave. I removed any bumps in the chamber. I ported the chamber trying to center the spark plug by removing material from behind it. I also removed any ridges in the valve seating area. I tried to remove any obstruction to flow. I tried for 65cc chambers to get a 7.64:1 compression ratio. I am using the Motorsport cam with .420 lift and roller followers. I know that I will be going to a bigger than stock turbo because of this increased flow requirement.
More combustion chamber pictures:
This is the exhaust side with the original size ports. Compare this to the next pictures which show the rough porting.
In this picture you can see the rough cuts in the exhaust ports that takes the outlet from 1.25 to 1.375 by raising the roof of the port and not by lowering the floor. This was done with an end mill. I had to remove the ridge that you see in the port by grinding. You can see the imprint of an exhaust manifold gasket. The 2.3 turbo did not come with a gasket from the factory.
A wider view of the above picture.
The exhaust side after cleaning up the rough cuts to make a smooth port.
This is the Intake ports before they have been ported.
This is the intake after porting. I just tried to smooth them out evenly. I did not try to match the gasket which is way oversized. However the venturi effect is improved by this bell shape.
Notice the copper color between the lobes of the cam. This is the A237 cam. I was told that this was done to the aftermarket cams as a protective coating. The head must be completely cleaned. Use bore brushes to clean all the passages. I filled up a 5 gallon pail with tranny fluid and put the head into it. This works well because of all the detergent in the trans fluid. Make sure to clean the lifter bores perfectly. Use a tap to clean out all the threads in the head or your torque readings will be incorrect and the head gasket will fail due to uneven torquing. After you have the cam and bearings installed squeeze the lifters to remove any oil if you are using the old ones and put in the lifter and assemble the valve and rocker to set the cold valve lash. Cold valve lash should be .035 to .055 inches between cam base circle and roller follower. When installing the head be very careful not to nick the gasket or the head. Replace the dowels with new ones from Ford if necessary. To remove the dowels put a bolt of the same inner diameter in the dowel and grab with a pair of pliers and twist them out.There are two dowels on the right side of the block for alignment.
This is the gutted upper intake.
This is the knife edged lower intake with a modified gasket. I forgot to flip the picture when I scanned it.
When I pulled the original head off there was a lot of oil in the number four cylinder. The block was leaking oil out of the left side of the head gasket. The Fel-Pro gasket was delaminated and cracked in the rear area. I have seen this on two other Fel-Pro gaskets. I assume that the gasket failed in this area because of the higher temperatures between cylinders number 3 and 4. The head bolts came out fine but the left rear bolt was a little looser than the rest. This would explain the oil leak since this is where the oil comes from the pump up into the head. The valves were all good. One thing I have noticed when doing heads is that the auxillary shaft pulley can be turned around and it has a mark on it like the cam pulley and aligning the pulleys is easier. This pulley is the same part as the cam pulley. All three heads I have seen had the pulley on backwards so that you couldn't see the mark on it.
This car is fast. Fast as in Autobahn fast. The power is still good at the bottom end but the top end is much improved. It will break the tires loose when I am in second gear, if I keep it floored like in a low speed passing situation. It keeps pushing you back in your seat when you have it at WOT. At 110 it feels like it used to at 80. The mods really increased the top end which was my intention.
Complete Mod's list:
88 auto XR, ram air fed K+N filter in fenderwell, Big VAM insulated from engine heat, ram air fed TC intercooler, brass cap and rotor, 8.5 Magnecors, Motorcrafts@.030, 10@BTDC, No KS, SVO PE, TPS @ .91, Ric Gillis boost valve @ 22 PSI, matched 35 lb. injectors, Sunoco 94, Motorsport roller cam, ported exhaust only in the head, ported lower intake, gutted upper intake, ported exhaust manifold, Mazda brake booster check valve in line with the PCV, 180 thermostat, 3 inch downpipe, hollow cat, Turbo Timer, stock 137K block.