Engine rebuild

Mike Kelley

Junior Member
Theory question. I am working on a replacement engine for my tudor.
I will be using a nos model B cam and an originial Ford "police" head.
What could I expect as far as an increase in horse power with these two mods? Thanks for any help
 
Theory question. I am working on a replacement engine for my tudor.
I will be using a nos model B cam and an originial Ford "police" head.
What could I expect as far as an increase in horse power with these two mods? Thanks for any help
This is only a guess, 50 -52 horsepower if you are lucky. You will need at least a reamed out model A manifold and model B carb to realize the potential of the cam and head. The stock B eingine was, I think, 52 horsepower. The B engine had the larger manifold and carb plus the nos cam. The stock B engine only had a compression ratio of 4.6 .The police head has a ratio of 5.2 and this should give a little edge. Remember it is not a nos B engine and my guess that if you made the carb and manifold changes mentioned I wouldn't expect much over 55. Good luck, I think it will be worth the effort.
 
Yes Purdy Swoft hit that on the money you will be looking at aprox 55 HP from dyno test I have done. I build 2 A engines the same a few years ago with Touring cams and 5.5 heads A carb and they both turned 50 HP. B carb gain about 3 HP.
 
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Mike,

Also consider lightening your A flywheel; the B flywheel was 10 lbs lighter than the A . Be sure to have the flywheel and pressure plate balanced if you decide to cut one down.

With the two changes you mentioned I would expect you will have around 52 HP plus or minus.

Ron
 
Consider larger intake valves

FWIW: If I were building the engine for myself, even with the B cam, I would install 1.7" intake valves and do a bit of blending in the intake ports. Along with all the other things mentioned.
I dyno'd an engine with similar mods and the result was 62 hp.
Good Day!
Dave in MN
 
What's ment by reamming the carb. and the manifold. I've never seen or done that. Tell me how.
I don't ream the carb. I ream the runner of the model A intake manifold to model B size. Some have problems setting up the manifolf for boring. If the manifold is not properly set up, some have ran out the side and ruined the manifold. I use adjustable reamers and ream by hand. Hand reaming is a slow process but It has worked well for me.
 
Mike,

Also consider lightening your A flywheel; the B flywheel was 10 lbs lighter than the A . Be sure to have the flywheel and pressure plate balanced if you decide to cut one down.

With the two changes you mentioned I would expect you will have around 52 HP plus or minus.

Ron
I installed a stock model B flywheel on our roadster. I weighed both flywheels, the one that I used was 16 or 18 lbs. lighter . It really made a big difference in throttle response and acceleration. A dual updraft manifold with good B carbs will probably add another 10 horsepower if used with a higher compression head and better cam
 
Its my understanding the additional weight of the B crankshaft, due to the increase in the size of the main and rod journals, resulted in the B flywheel weight being reduced by the same amount ?

Ron
 
Drilling out an A manifold to B size

What's ment by reamming the carb. and the manifold. I've never seen or done that. Tell me how.


Greetings,
You don't ream the carb but you can open up the intake manifold.
I have some pictures on my website (address below) of the process with the drills sizes I use. It is a real simple process. The drill size is noted on one of the pictures.

Look for:
Intake manifold enlargement under the Other Model A services area...click the link.
There are a number of pictures so it may take a little time to load. (1.78mb)

My website: www.durableperformance.net


Good Day!
Dave in MN
http://m.www.durableperformance.net/Intake_manifold_enlargement_website_doc.8.19.10.pdf




http://www.durableperformance.net
 
Its my understanding the additional weight of the B crankshaft, due to the increase in the size of the main and rod journals, resulted in the B flywheel weight being reduced by the same amount ?

Ron
I'm not sure of exact crankshaft weights. There was three different crankshafts used with the B engines. The B engines produced in 1932 did not use the counterbalanced crankshaft. The early crankshafts were heavier than the model A crankshafts because of larger bearing journals. The forged counterbalanced shaft was heavier and the BB shaft with pressed on counterweights was the heaviest.

If using a heavier counterbalanced crankshaft you will need to remove more weight from the flywheel than the weight of the counter weights to realize any gains in throttle responce and acceleration. otherwise the rotating weight will remain the same.
 
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