WESMANTECH
New member
Can someone tell me what are manufacturing upgrades from Model A to a Model B engine. If there is a website or a article out there I haven't found it yet, or I'm looking inn the wrong places.
Model A vs Model B
- Thread starter WESMANTECH
- Start date
There are many minor differences, and a few major ones.
The B crank and crank journals are much larger diameter, making the crank stronger. That also makes the bearings larger (more surface area). The exposed oil return tube on the side of the A engine is replaced by a groove in the side of the casting, and a larger valve side cover. The intake manifold has a larger inside diameter, and the carburetor has larger diameter throat. The distributor is different, the head is slightly higher compression, the water pump has 3 instead of 4 bolts, the water neck is on the water pump itself, etc.
The B crank and crank journals are much larger diameter, making the crank stronger. That also makes the bearings larger (more surface area). The exposed oil return tube on the side of the A engine is replaced by a groove in the side of the casting, and a larger valve side cover. The intake manifold has a larger inside diameter, and the carburetor has larger diameter throat. The distributor is different, the head is slightly higher compression, the water pump has 3 instead of 4 bolts, the water neck is on the water pump itself, etc.
Joe K
Well-known member
The Model A engine was nominally 40hp. The Model B engine was nominally 50hp.
The biggest reason for this improvement was in the exhaust/inlet ports, primarily the inlet manifold, which was increased from about an inch to 1-1/4 inch diameter. You can tell a Model B inlet manifold by the "flat top" on the manifold.
Many will take a Model A inlet manifold (rounded top) and "ream" the passage immediately above the flange. The two branches to the cylinders are similar in diameter between Model A and Model B.
The cam shaft for the B had it's own improved grind.
Model B distributor had a "centrifugal advance."
Other differences include the "C" counterweighted crank which was not immediately available, and steps taken around the oil pan tray details (including the shield) to limit oil consumption.
I see others are taking advantage of this warm summer day by seeking refuge in front of the air conditioner and responding to queries of interest.
Joe K
The biggest reason for this improvement was in the exhaust/inlet ports, primarily the inlet manifold, which was increased from about an inch to 1-1/4 inch diameter. You can tell a Model B inlet manifold by the "flat top" on the manifold.
Many will take a Model A inlet manifold (rounded top) and "ream" the passage immediately above the flange. The two branches to the cylinders are similar in diameter between Model A and Model B.
The cam shaft for the B had it's own improved grind.
Model B distributor had a "centrifugal advance."
Other differences include the "C" counterweighted crank which was not immediately available, and steps taken around the oil pan tray details (including the shield) to limit oil consumption.
I see others are taking advantage of this warm summer day by seeking refuge in front of the air conditioner and responding to queries of interest.
Joe K
rotorwrench
Well-known member
The 1932 model B introduced the early partially synchronized transmission which had a new clutch housing. The serial number is stamped on that clutch housing. The cooling system was internally enlarged a bit around the valve pockets to aid in cooling. These engine castings tend to crack more easily due to the thinner jacket walls in there. Crankshafts were larger in journal and eventually counterweights were added so they could run smoother. The fuel tank was moved to the rear on model B cars so it had to have a fuel pump added to block casting on the front right.
Most changes were subtle but there were more than can be seen externally so they still resemble the model A. Oil pans have to be modified to work in the model A application but plenty of folks run them in their A vehicles.
Most improvements were small
Most changes were subtle but there were more than can be seen externally so they still resemble the model A. Oil pans have to be modified to work in the model A application but plenty of folks run them in their A vehicles.
Most improvements were small
Marshall V. Daut
Well-known member
Other than performance upgrades that differentiate the two engines, there are a couple obvious additions and deletions externally. There is a provision on the passenger's side behind the timing gear side cover for a mechanical fuel pump, which is driven by the camshaft. A Model B has no oil return pipe on that side of the engine that a Model A does have. The valve cover on a Model B engine is much taller than a Model A valve cover. The three-bolt water pump has already been mentioned versus the Model A's four bolt pattern. The Model B oil filler pipe is much bigger than a Model A's with a matching larger oil cap. Also, the exhaust manifold has a 45 degree angle bend towards the rear, whereas a Model A exhaust manifold dips straight down. A raised, embossed letter "C" often appears on a Model B cylinder head, NOT a letter "B", which was found on the 1931 so-called "Police Head".
These are the external differences I can think of off the top of my head. Oh, yes - the distributor is different between the two engines.
Marshall
These are the external differences I can think of off the top of my head. Oh, yes - the distributor is different between the two engines.
Marshall
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Marshall V. Daut
Well-known member
Another difference is more subtle and has caused many a Model A guy nightmares if the two timing gear front covers are switched. The timing gear pin hole is located in a different place on a Model B cover. As I recall, it is about 1/2 inch higher. The purpose of that hole is still to find TDC of #1 piston, but I believe the upgrade to a centrifical force Model B distributor necessitated this move. If you put a Model B timing gear cover on a Model A engine and use the reversed pin to set the initial timing, it will be off a few degrees. This, of course, can be compensated for by moving the distributor cam a little and allowing your ear to tell you if the timing is correct. You can also feel if the engine is too retarded or advanced. The pin method merely gives you a good ball park initial TDC setting. It's up to you to fine tune the distributor cam to make the engine happy.
Marshall
Marshall
Marshall V. Daut
Well-known member
Too bad they didn't produce more of them.
Also too bad Ford didn't make the Model B block STRONGER! They are crack monsters, especially in the valve area on top of the block. Some guys have had good luck with Model B blocks. My luck with three or four has been horrendous in terms of money spent and frustration incurred. They ALL cracked, even a low mileage one I bought and had rebuilt. The last "B" block I had developed a crack in a cylinder 6" long that couldn't be repaired by re-sleeving the block. I paid $600 thirty years ago to have the block heated in a special oven for that purpose and then welded. A local shop in the Phoenix area did this. Of course, it cracked again and I was finished with "B" blocks forever. Three strikes and you're out! The Model B bolt on-components are nice (crankshaft with larger bearing journals, camshaft, cylinder head, intake manifold, carb), but other than an increased oil pressure, a Model A block is better to beef up. Trim the main journals fit the Model A bearing saddles and leave the rod journals as is and you'll have a stronger bottom end engine than the stock Model A. You really have to work at cracking a Model A block. I've only seen a couple and they were mostly freeze cracks, some of which could be repaired externally.
Marshall
Also too bad Ford didn't make the Model B block STRONGER! They are crack monsters, especially in the valve area on top of the block. Some guys have had good luck with Model B blocks. My luck with three or four has been horrendous in terms of money spent and frustration incurred. They ALL cracked, even a low mileage one I bought and had rebuilt. The last "B" block I had developed a crack in a cylinder 6" long that couldn't be repaired by re-sleeving the block. I paid $600 thirty years ago to have the block heated in a special oven for that purpose and then welded. A local shop in the Phoenix area did this. Of course, it cracked again and I was finished with "B" blocks forever. Three strikes and you're out! The Model B bolt on-components are nice (crankshaft with larger bearing journals, camshaft, cylinder head, intake manifold, carb), but other than an increased oil pressure, a Model A block is better to beef up. Trim the main journals fit the Model A bearing saddles and leave the rod journals as is and you'll have a stronger bottom end engine than the stock Model A. You really have to work at cracking a Model A block. I've only seen a couple and they were mostly freeze cracks, some of which could be repaired externally.
Marshall
The exposed oil return tube on the A engine was actually replaced with two 0.75 inch holes in the floor of the valve chamber that drain directly into the dipper tray at a point between the 1 & 2 and 3 &4 dipper reservoirs. The "groove in the side of the casting" on the B engine is the oil feed channel leading to the pressurized main bearings.
I know that. My super-power is helping newbies. When someone asks me how to BBQ a steak, I tell them to hold it over a fire, I don't first describe how to fabricate a grill. So I keep it simple.
Charlie Stephens
Well-known member
To illustrate some of the earlier posts. First the cut off oil pan being used with my Model A transmission and flywheel housing. I left a strap of metal rather than trying to remove the rivets and risk a leak Second the Model B timing cover with the timing pin located at the top of the oval boss instead of in the center of a round boss like a Model A. I have heard there were a few post production covers with oval bosses and the pin located at the bottom so they could be used on a Model A but I have never seen one. Finally the Model B engine has two additional water holes shown circled in the attached photo. You need to address these if you start mixing heads and blocks.
Charie Stephens
Charie Stephens
Attachments
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Charlie Stephens
Well-known member
If you are calling a 1933-34 engine a Model B note that the crankshaft pulley is shorter, the water pump is shorter and the generator mount on the timing cover is moved
back slightly towards the rear of the car to accommodate the sloped radiator in those years.
Charlie Stephens
back slightly towards the rear of the car to accommodate the sloped radiator in those years.
Charlie Stephens
WESMANTECH
New member
Well I bought one of these nightmares. It came in my 30 coupe, I have an A model distributor but I found out that the front timing cover was not changed to an A model cover hence the timing pin sets at 19 BTDC with the A distributor makes it kinda difficult to set the timing. The original thought behind my first post was to change the front timing cover. after finding out that the crank journals were larger I was wondering about swapping the covers, is the "snout" on the front of the crank the same size A vs B, will the A cover require machining? The other thought I would like to add an oil filter. what would be my best optionone mounted behind the timing cover?
WESMANTECH
New member
Gentlemen I am taken back I didn't think there was that many differences.
WOW!! I need to take some serious notes THANKS A BUNCH! GUYS!!
WOW!! I need to take some serious notes THANKS A BUNCH! GUYS!!
Joe K
Well-known member
My Gordon-Smith air compressor is built on a former "B" block. Of course the compressor flips between "idle" status and "compressing" status depending on the tank pressure at the moment.
Normally this change would require one to adjust the timing of the distributor - but using a B block brings the advantage of a centrifugal advance for the B distributor. So it can change between speed states and do so "automatically."
I also found in a brush-boring that the block has a crack between the No. 2 exhaust valve and not quite into the cylinder bore. The block may have been specifically chosen for conversion to an air compressor: on the Gordon Smith, cylinders 2 and 3 are converted to air compressor - and the special head has gasket "filler pieces" to cover over the intake and exhaust valves on 2 and 3. So while this block has the classic Model B cracks - it's perfectly suited for use as a compressor.
Well, I think. I'm hoping to have the block "pinned" and eliminate with certainty any possibility of a leak.
Joe K
Normally this change would require one to adjust the timing of the distributor - but using a B block brings the advantage of a centrifugal advance for the B distributor. So it can change between speed states and do so "automatically."
I also found in a brush-boring that the block has a crack between the No. 2 exhaust valve and not quite into the cylinder bore. The block may have been specifically chosen for conversion to an air compressor: on the Gordon Smith, cylinders 2 and 3 are converted to air compressor - and the special head has gasket "filler pieces" to cover over the intake and exhaust valves on 2 and 3. So while this block has the classic Model B cracks - it's perfectly suited for use as a compressor.
Well, I think. I'm hoping to have the block "pinned" and eliminate with certainty any possibility of a leak.
Joe K