From H4H4 (HOT FOR HOT FOURS) #3-0 with Permission of Author

Following are some options that will give more power, better fuel mileage and still not hurt bearing life.  I am assuming a couple of things, 1) We are building a Model A engine (as opposed to a B engine)  and 2) that we want it to idle nicely and have good “driveability”.  These are big assumptions as it is kind of like asking how fast is fast?  Keep in mind that if you ask 10 Model A ‘experts’ you will most likely get 12 different answers, most will be good, so you just take it all in and decide for yourself what is best for you.

 Block:  The early 1928 blocks were not as strong in the rear main bearing web area as the later blocks.  The earliest ones had no reinforcement ribs and used thinner bearing caps.  Later versions of the 5-cam bearing block were reinforced with 2 ribs, at some time later Ford dropped the 5-cam bearing block and added a third reinforcement rib.  The latest of the A blocks had thicker material in several areas.  The later the block, the better, as far as strength goes.

Crankshaft and rods:  The crankshafts in the Model A are dimensionally all the same but the early cranks were shaped differently between the rod bearing throws, some people refer to these as “beaver-tail” cranks.  These early cranks were slightly lighter so could result in quicker acceleration but there is no actual horsepower advantage or disadvantage.  A few early engines had X shaped rods.  I know little about these rods, they may be lighter but I do not recommend using them as they are an unknown entity to me.  If using original rods be sure that the bolt areas are in good shape, not stretched or thin threads.  Also try and find rods that have not been filed or hack-sawed to mark them for the cylinder that they belong in, this can weaken them.

Pistons:  Any new piston made for the Model A will work very satisfactorily and have long life.  If you can get pistons with narrower than stock rings, the ring life will be longer and have better sealing so less blow-by.  Forged pistons are not needed in a touring engine, or even in a hot street engine.  I have run cast aluminum pistons in an engine that I ran in a dragster and turned that engine 6,000 RPM on a regular basis.  I also ran those same pistons at Bonneville and had no problem with them.  Cast pistons actually have some advantages over forged for street engines.  Allow adequate piston-to-wall clearance.  Ford said use a maximum of .002” clearance.  This is not adequate for today’s pistons and is even worse if you drive a lot and use an overdrive.  I recommend a minimum of .003”, I usually set my street engines at .004”.  Too tight in this area will result in scored pistons and cylinder walls.

Bearing life:  The most important thing is to use good quality, high-speed babbitt and have it done by someone with a good reputation.  Secondly use modern oils and a full-flow filter.  Use a crank that is as near standard as you can find and have it counter weighted.  Counter weighting won’t add horsepower nor necessarily make the engine feel any smoother but it will help bearing life.  Have the entire engine balanced.  It is best to not use a crank that is more than .030" undersize but I have seen Model A cranks that are as much as .060" undersize.  I recommend a 3/16” line directly from the oil pump to the center main bearing cap, the center main takes the most beating and extra oil will help.  Remove weight from the flywheel.  This will not only help bearing life but will make your gear-shifts faster (as higher compression will also).  Converting the engine to full pressure oiling is not necessary unless you are going to race it or use very high compression or turn the engine high RPM, 4000 or better.  Stock oiling has some advantages over a pressure system for guys that don’t drive their A’s every day, the main one being that no matter how long it has been since last run, the rods, cam, etc. will have oil to them at the first revolution (because oil is always ready in the dipper tray) without having to wait for oil to be pumped thru all the lines, crank, etc. to get to the rods.  Check the dipper tray for rust-out by cleaning it thoroughly and holding up to sunlight, if porous you will see pinholes which need welding or brazing.  Insert bearings are a good way to go but certainly not a necessity.

First start-up: When you are ready to start the engine for the first time after the rebuild, do two things immediately before starting the engine.  1) Pour 4 quarts of oil in the pan via the oil filler tube. This fills the dipper tray that oils the rods.  2) With water in the engine and everything ready to go, remove the distributor and its drive shaft, then pour one quart of oil down the distributor hole, this will fill the valve chamber with oil and start oiling the main bearings.  It just takes a minute or two to re-install the dist. which gives the oil time to get to the mains.  Do not use non-detergent oil.

The above pertains to the Model A block.  The Model B block has a better oiling system with pressure to the mains and bigger main & rod bearings.  The bigger bearings also make for a more rigid crank.  The downside to Model B blocks is that they are thinner on the top deck and therefore are more apt to crack, they are also much more expensive to buy if you can find one.

I recommend all the standard rebuild items now in common use, i.e. one-piece valve guides, hard exhaust seats (no harm in putting them in the intakes too but not as important), GM valves etc.  I always use an aluminum timing gear for longevity. 

Now the fun part, or hard part, depending on how you look at it.  Higher compression and a bigger carburetor are the two easiest and most important paths to more power and speed.

Cylinder head:  Use 6:1 compression ratio or higher, 7 is not too high but would not go higher than 7:1.  If you want to stay with the stock look, the Snyder (my preference) or Brumfield heads work very well.  If you want to go higher I would recommend someone else’s head at around 7:1.  I don’t think the Snyder or Brumfield combustion chamber design is good enough for more than 6:1, they even used to advertise that you shouldn’t go over 6:1.  Specialty Ford Parts / 9109 Garvey Ave. /  Rosemead, CA 91770 / 626-288-2121 makes Winfield heads that, in my opinion, have the best combustion chamber.

Carb & Manifold:  At the very least use a Model B carb and manifold.  I think the ideal carb is a Winfield Model S but they are hard to find.  The next option is a Stromberg ‘97' or other, more modern, downdraft carb such as the Weber 32/36.  You might get by without a fuel pump on some downdrafts, I ran a’ 97' on my ‘30 Tudor with no problems. ‘28 & ‘29 Model A’s have a lower gas tank and it gets a little iffy.  I recommend a single carb rather than two because of the simplicity.  (OHV heads will probably require a fuel pump as the carb sits higher.)  If using a Stromberg carb with an electric fuel pump a regulator will be needed, regulate to no more than 3 PSI.

Cam:   Of course a Brierley cam is the best choice that you can make!  For most mild performance engines I recommend a Model B cam or a B grind on a Model A cam.  There are a lot of other options but everything is a compromise and the B grind works well all around, you still get the smooth idle and low-end torque with good mid-range power.  If you go to a larger carb than the B you can utilize a slightly hotter cam such as my “C” grind or Winfield IR.  If you don’t have a local source for cam grinding I can regrind your cam. 

Valves:  Some engine builders use larger intake valves but unless you go to a hot cam and a large or dual carbs, there is little advantage to this and it is a lot of trouble.  The exhaust valves and ports are very adequate in size and shape but I recommend one-piece guides and good valves such as the exhaust valve from an early 60’s GMC 305 V6 engine.  These valves can be used as both intake and exhausts.  If you decide to go to larger intake valves the easiest valve to install is the 216 Chevy intake valve.  It has a 1&11/16” head diameter and a 30 degree seat angle.  The 30 degree angle allows for better flow towards the piston.  The valve guides from the 215 Buick V8 (Egge part # G-880) will press right in the A block with no modification needed although I shorten them to stock A length for easier valve spring installation.  These are 11/32” I.D. and fit both of the above valves.  Stock valve springs work well but should be installed with a shim for more seat pressure, this insures good valve cooling and is necessary for a performance cam so the valve follows the cam at higher RPM’s.  I recommend seat pressure of 40 PSI on a B grind cam and 60 on a performance cam.  Keep in mind that when you change to one-piece guides you have lessened the installed height as the stock guides have a shoulder on them that the spring sits on, so a spacer is necessary.

Ports:  Both the intake and the exhaust ports should be ground smooth with a die-grinder.  The intakes can be enlarged slightly at the valve for increased flow.  Do not polish the intake ports, this will cause fuel to separate from the air/fuel mixture on the way into the cylinder.  The exhaust ports can be smoothed and polished.  Match the port to the hard valve seats.  The intake seats should be narrower than the exhausts, the exhausts need some width for cooling, narrow seats seal better on the intakes.  The intake valve should seat near its outer diameter, the exhaust in the center of the seat area.

Exhaust:  The Model A exhaust manifold is quite good, Aries makes a high-flow stock-looking muffler that works great.  Headers are even better but are not permitted in our hill climb stock or touring classes.

Ignition:  Probably most break-downs and poor performance in Model A’s are caused by the ignition system.  I highly recommend a good electronic ignition, either a conversion such as the FS ignition or a good aftermarket distributor such as a Mallory.  Do not use too much spark advance.  Most flathead engines can use only about 26 to 28 degrees total advance.  Detonation will ruin bearings quicker than anything.  That is what I don’t like about the Brumfield high compression head, the chamber is not suited for high compression.

Cooling:  The Model A radiator will usually be more than adequate to cool your engine, if in good condition.  Do not scrimp in this area, spend a few bucks and have your radiator cleaned by a professional  shop.  The Model A water pump will also work well, use a leakless pump or one that will not leak.  I use the early V8 pump (an adapter is needed) and Cling’s serpentine belt.  The V8 pump has a modern carbon seal.

Gears:  That about covers the engine, but there are other things to consider too, such as a V8 or other transmissions and an overdrive.  3.54:1 rear end gears are an option but an overdrive is best as they give you the best of both worlds, a low gear for acceleration away from the stop light and a high gear for freeway cruising.  Too high a gear is not good, as the power needed to push a barn (a Model A) thru the wind goes up quite fast in relation to speed.  A final drive ratio of about 3:1 is as high as most Model A’s can effectively use.  A heavy fordor cannot pull as tall a gear as a lighter body style or speedsters which are lighter and generally have a smaller frontal area.  Too high a gear will result in poor performance, poor gas mileage and could damage the engine, especially the rod bearings as the engine will be “lugging” all the time.

Brakes:  Now that you are running good it’s time to think about stopping.  At the very least install cast iron drums and have everything in as good of condition as possible, floaters are a plus too.  I prefer hydraulic brakes as they are far superior in stopping ability and ease of maintenance.  1935 Ford mechanicals are another option that is superior to Model A brakes, they are usually used only on the front axle but I installed them on the rear of my speedster and they really help.  They are the same width and diameter as the hydraulic brakes.

With the above modifications you will be able to drive comfortably over any terrain, at safe highway speeds and still have as good or better fuel mileage as when the car was new.  ENJOY!

That about covers it unless you want to talk about overhead valves and speedster bodies!

Keep tuned for the Hot Four Banger Article. (Gearhead)