Is your Bantam in need of a new heart?

$4,000 is a lot of money, there is no question about that.  So when confronted with a price tag calling for that much money, it’s best to be an intelligent buyer.  This engine has been listed for auction by a seller who has been listing a lot of Bantam and Austin parts over the past few months.  This engine is probably one of the greatest finds in the collection because of the potential it may offer.

I don’t have an awful lot to say about this engine, as people have their different views on rebuilt engines and engines that are rebuilt but lay dormant.  While some may recommend tearing it down to go through the engine, others may be willing to run it as is.  If you’re willing to accept this as being equal to a modern rebuild where all of the parts have been wet magnafluxed, rebabitted, and assembled with the highest quality materials; this could be a bargain.

In theory, I believe it should be torn down and inspected before being run; but then again I am usually a “get the ether and a jumper pack” kind of guy because I just want to hear the engine come to life (which is a terrible idea).  I’ll let you be the judge, but I’ll give you a few things to consider:

  1. In the 1980’s, parts may have not been magnafluxed or at least not wet magnafluxed (which is a far superior method of crack detection).
  2. Original Bantam rod bolts are notoriously weak, we do not see a bill of materials indicating what was used.
  3. New main bearings were cited in the ad. Does that mean the rebuilder used NOS front and rear bearing retainers with their original poured babbit, were original retainers rebabbitted, or were some sort of inserts used?
  4. We don’t know if the new rods were the NOS 38 style rods which were available with original babbit or something else.  In any event, how were they modified to accommodate the undersized crankshaft?
  5. The engine does not appear to have any of its openings sealed.
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This is what a NEW or never run rebuilt Brennan IMP looked like in the exhaust ports after laying dormant for years.

 

 

 

This engine could be great or it could be a very expensive (but pretty) collection of parts.

What are your thoughts? (A few people have already chimed in and have inspired some additions to this post).

 

Click here to see the American Bantam Engine

 

Autopsy of an American Bantam Engine: Part III

Welcome to the final installment of the disassembly.  Could the engine come apart a little more?  Yes.  In fact, the oiling system will probably need to be taken out of this engine, but everything is at a stand still until I know what condition the crankshaft and rods are in.

Remember that rear main bearing carrier I showed you a photo of the other day?  That is the last obstacle between us and the crankshaft.  Although the piece is cast iron, it has been wedged into an aluminum crankcase for decades, and beside being shrink fit into the crankcase, it also may have some corrosion between the two parts.  This is why you need a heat source to expand the aluminum to make it easier to pull out the main carrier.

First, take the two bolts you bought and thread them into the to holes in your bearing carrier.  DO NOT thread them all the way down or attempt to pull the carrier out without heat.  If you do, you will probably be experiencing extreme anger and frustration, as the carrier ear snaps off and the carrier remains steadfast in its hole.  Threading the bolts in now will prepare you for when the engine is up to temperature so you wont waste valuable time and expansion while searching for parts.

The last time I did this, I consulted the ABS’s engine manual which encouraged using an oven to expand the aluminum.  Not wanting to put anything Bantam in my oven, I spoke to a club member who suggested the idea of a space heater.  He recommended one of those radiant heaters,  however, they have gotten very hard to find.  I instead bought a stanley unit from Lowes.  Then I made a little heat corral of cardboard boxes surrounding the engine in the middle of my garage to ensure that as much heat as possible soaked into the engine before being stolen by my frigid garage.  This time, I had something better, a metal crate with wooden sides to corral the heat.  Either way, don’t get reckless, and please make sure that your heat corral is not on the verge of becoming a heat source itself.

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Aiming the heater at the back of the engine and closing it in, I set my timer for 20 minutes.  Set to high heat and high fan, I began my wait.  As I said, keep your eyes on your set up.  Here is my observation station and view:

Once the first twenty minutes has passed, check to see how warm your crankcase feels.  More than likely, you’ll need to run the heater for at least another 20 minutes at full blast.  After 40 minutes, I turned off the heater as the aluminum was feeling quite warm and began to tighten the upper bolt.  Immediately, I was able to see the carrier pulling away from the top.

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You should only crank each bolt a little bit before moving to the next, hoping to remove this as evenly as possible.  The lower bolt however did not turn without a lot of resistance and the lower part of the carrier showed that it wasn’t ready to budge yet.  So I turned the heater on and set the timer for another 15 minutes.

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At the end of the 15 minutes, I tested the lower bolt and as it threaded deeper into the carrier I saw it separate from the block at the seam where they are joined.  Moving between the two bolts at even increments, the carrier came out very easily and exposed the crank entirely at the rear.

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Reaching in through the bottom of the block with one hand, I carefully slid it out to my other hand.

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Here is the bounty of our efforts:

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The next step is to take this crank and the connecting rods to the machine shop to see what I’m dealing with.  Although you can have the crank hot tanked, I’ve heard that you don’t want the rods hot tanked as it can adversely affect your babbit.  You should hand clean the rods with good detergents like brake parts cleaner, etc.

I will be taking this crank in and asking them to check it for cracks, straightness, and size of the journals.  I’ll also be asking them to check the rods for cracks and the size of the bearing material.  It’ll take a few days until I know for certain what the results are, but it’s always important to know that the most important parts in your engine are in good shape.  As the old adage goes, without a crank, there can be no Bantam engine.

Autopsy of an American Bantam Engine, Part II

This is the second installment in the tear down procedure.  I left off with needing pullers to get the rest of the engine ready in order for me to pull the crank out.

If you do not have a three jaw puller, you can usually borrow them from Autozone or Advanced Auto Parts.  They charge you the full price of the tool, and refund it upon return.  It’s a great service, however the tools are generally about the same quality you would find at a Harbor Freight.  So, if you decide you’re in love with the tool or it is something you will need repeatedly, it would be cheaper to buy it almost anywhere else than to keep the one from the auto parts store.

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I left off with the crank pulley still attached to the crank.  Since the cover behind it is aluminum, there is no way I want to pry against it, even though it’s already broken.  The piece that is broken is very repairable.  The pulley however, is already broken, with a large chip out of it.  I believe they make special pulley pullers, but I didn’t really think about it at the time I was renting this one.

Keeping the crank engagement bolt in place, I attached the puller as you can see below.  When you do this, make sure to thread the bolt into the crank so you don’t foul up the threads, but leave room so you have where to move the pulley.  Removing the washer will help.  If you don’t provide ample room, you may not realize that the pulley is infact moving, but you are just pulling against the bolt.  This will result in breaking the cast pulley even more.  I’ll let you guess how I found that one out.

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The pulley is kept in place with a key, but it pulls off nicely.  Once it is off, removing the perimeter bolts of the cover allow it to free itself and you are then faced with the next challenge, the timing gears.  At first glance, it looks as though the right way to do this is to remove the nut from the cam to take those gears off.  This nut has been marred in an effort to keep the assembly attached.  Attempting to take the nut off ended up yielding the entire cam assembly.  This is okay for me for now.

The last challenge on the front end of the crank case is the timing gear attached to the front of the crank.  The puller and the crank engagement bolt will come in handy here.  Make sure you have the jaws engaged so you don’t damage the teeth.  (This one I didn’t learn the hard way).  You may want to soak this in your favorite penetrating fluid.  Now all of the front end impediments to pulling the crankshaft out have been dealt with.  If you look carefully, you can see more damage to this crank case, the lower two bolt holes are broken.

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The next challenge will be dealt with tomorrow.  This final step in pulling the crank out is by far the most important.  Once you pull off the flywheel, you will see 6 fasteners holding in the rear bearing carrier.  You will also see two holes that have nothing in them.  These holes are threaded and are going to be very important in getting the crank out.

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For part three, make sure you have two bolts that thread into those holes that are over an inch long and a space heater.  In part III, you see what to do with them.  Don’t touch your engine until you read the rest.

Also, this is the perfect time to say, if you haven’t joined the clubs, DO IT.  If you’re not interested in the club scene or the great people you’ll meet, at least do it for the tech information. The Austin Bantam society has a wonderful CD indexing all of the tech articles that both clubs have put out during their existence.  Among those articles is most of a great engine rebuilding manual.  The guidance of that manual and the club members have helped me greatly in this process.

Remember, when it comes to Bantam parts; don’t break them, please.

 

 

Autopsy of an American Bantam Engine, Part I:

The odometer only shows 37,000 miles or so.  The frame looks like new.  The sheet metal isn’t even that beaten up.  So what happened to this car?

I had the chance to pick up some parts from an early 1938 coupe this weekend and with it was an engine.  I had known about this car when it had first hit craigslist and ebay about a year ago.  In the interim, a person bought it to build a hotrod from the body and was looking to sell the rest of the parts to make room for his project.

As you know, Bantam engines have a reputations for crankshaft problems, and I was thinking that with everything presenting as it was, perhaps crankshaft failure was the reason for this car’s premature parking.  Looking at the crank case, I saw it was obliterated, but wasn’t sure what else was wrong with the engine. I got the engine home to find the flywheel turned, but not all of the way around.  Even though it was late, disassembly began.

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Finally home and waiting for disassembly

As you can see, the entire back of the crank case is destroyed where the cast in bell housing meets up with the cast iron bellhousing adapter on the transmission.  Even more strange is that a large ring is entirely missing from the flywheel just aft of the ring gear.  Without this ring, there is no way to mount a Bantam clutch assembly to this engine.  If you look at the corner of the oil pan, you can look right into the engine.

 

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With the pan opened up, the crankshaft became visible as did one of the reasons the engine wouldn’t turn.  The rod bolt for piston 4 was interfering with the bracket for the oil jet.  Also visible are signs of welding on the oil dippers integral with the caps and shims, possibly indicating a rebabbitted engine.

Further inspection shows that this engine had blown up at one point as there is a lot of damage to the crank case which has been welded up.  Presumptively, someone was hoping to bring this engine back to life, and forgot to tighten one screw all the way.  The flywheel that came with the engine was rubbing on the back of the block as a spacer was missing, but placing a different flywheel assembly on the rear alleviated that issue.  If you look, you can see the difference between a correct flywheel and one that has been heavily damaged.

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Every aluminum part on this engine, except for the intake and carb are damaged.  There is no doubt that this engine had a hard life.  It’s actually amazing that the intake and carb have survived as they are most often broken off while all of the other pieces are fine.

In order to take the crankshaft out, which is the ultimate goal, I need to take quite a few parts off of the engine.  Taking the pistons out revealed a crankshaft with very nice looking journals and an odd assembly of rods.  This engine has two rods marked number 1 and no number 4.  Each rod has had a number of lines filed into the beam indicating which cylinder it corresponds to and attempts to cover up the original markings are present.  Two of the rods are part number:  A -3677 while the other two are A -3677 X which markings are quite different from the others.

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The cylinder block looks quite nice upon closer inspection.  Here are a few miscellaneous photos highlighting the condition of this engine.

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Although I was hopeful that this engine would have shown itself to be in better condition when I picked it up, all is not lost.  There are some really great parts on this engine that may either allow an entire other engine to be rebuilt (if the crank comes back good), or a bunch of parts that may help several other engines get back together.

The next installment will show the removal of the crankshaft and further disassembly.