Getting Started in 2013, Part #5, ‘Allan Able’ short block.


Continuing here, we are going to look at one of the least expensive short blocks that can be built as a flight engine. This takes into account lessons we have learned over the years. Although this is inexpensive, it is far better than a handful of short blocks that I see during a year of Colleges, were some local expert talked a builder into doing it his way, and ended up grinding the crank radiuses off or not threading the crank for a safety shaft. Following the plan here will keep you on track even if you are on a very tight budget. At the end I will cover some options and notes. CC stands for Clarks Corvair parts, SR stands for Summit Racing, ELS stands for Ebay Larry’s Corvair parts, and ECA stands for Ebay California Corvair parts.

Crank group (1000)

1000- Crank Moldex, ($600 typical price for work)

1001- Crank gear (used, from core)

1002- Crank gear key (CC-#5858, $1.50)

1003- Crank gear gasket (CC-786A, $1.88)

1004- Rear keys -2-(CC-#5858, $1.50, $3)

1005- Fuel pump eccentric (used, from core engine)

1006- Spacer (used, from core engine)

1007- Bronze distributor drive gear (used, from core engine)

1008- Oil slinger (used, from core engine)

1009- Main bearings (ELS-$88)

1010- Connecting rod bearings (ELS-$59)


Cam group (1100)

1100- Cam ( CC, part 8800R, $170 )

1101- Thrust washer (used, from core engine)

1102- Key (CC-#5858, $1.50)

1103- Cam gear (ELS- $35)

1104- Hydraulic lifter set -12 total- ( $2.99each, $36)

1105- Cam lubricant (comes with OT-10 cam)

1106- ZDDP oil additive (SR,$16)

Case Group (1200)

1200- Case -2 halves with studs- (used, from core engine)

1201- Main case bolts -8- (used, from core engine)

1202- Pipe plugs for oil galleries -2- (used, from core engine)


Looking at the above prices, the total is $1,011.88, a very reasonable price to get the case closed. Some options: ECA sells an 1103 cam gear for  $54 that is a USA billet item that I have not yet used, but I think this will turn out to be a $19 upgrade well spent. The  1100 cam here is a reground OT-10 from Clark’s. It’s pricey, but good. On an extreme budget, look at a ELS reground Isky 270 at $85. This isn’t as good as an OT-10, but it is far better than stock and better than a once proposed internet idea called using a ‘delta’ cam.

If you want to learn something about picking who has quality control on making cams or regrinding them, Read Harvey Crane’s website about the machines companies use. I have Known Harvey for 20 years, he is an airplane guy, lives at Spruce Creek and most people concede that he is one of the worlds leading experts on cams. OT-10s and Iskys are made on better equipment, and that’s what counts when it comes to reliability.

So a guy with a reground 270 and a gear upgrade is still only at $940 or so. To be fair the one issue here is that the crank gear has to come off before the crank is processed and later be put back on. The GM manual shows how to do this, but few homebuilders want to do this or have a 20 ton press. You can leave the gear on and let Moldex nitride it with the crank, but I am no longer in favor of this because people don’t take enough care to carefully clean the gear teeth later. There are literally more than 150 cranks flying that have had the gear nitrided in place, so there is a long track record of it working, but that shouldn’t prevent anyone from trying to do better today.

This isn’t the least expensive way anyone has gone. If you are lucky enough to find a GM factory nitrided crank that is still Standard size and you are planning on putting a 5th bearing on it, you could skip about $400 of the Moldex price because it would just need to be threaded, polished and Magnafluxed, about $200. I have an engine in the shop just like this right now, but it is a rare chance these days. But a builder with a GM 140/Turbo crank is good shape could get to the case closed stage for $550 or so.

I would not be afraid to fly such an engine, although I am going to work to later convince every ‘Allan Able’ builder to install a retrofit Gen. 1 Dan bearing. 5th bearings make sense for every builder, and the retrofittable nature of Dan’s Gen 1 bearing allows Builders to get started today, make progress, and work the bearing in later. 

From my personal perspective I would rather fly any engine that was carefully built around a GM 8409, even one on a very tight budget, than any engine that was built around a Chinese crankshaft sold on the internet by a guy who advertised them as “great for aircraft” although he has never flown in a light plane himself. Understand that the very first one of these cranks put in a plane failed and revealed a hidden factory repair. They are Made in China, sold by a LLC, that is owned by a Canadian. (I have many friends from the frozen north, America made Jim Beedee, we take a back seat to no country when it comes to marketing rip off artists) That triple condition means that if anything ever goes wrong, no one is going to stand behind it. It is the perfect legal firewall for a guy who knows nothing about planes but wants your money to hide behind. No one would tollerate a person who has no medical training dispensing drugs or telling patients what is the best treatment. Likewise, no one should be tollerant of any person who has no aviation training telling people what is ‘best’ for aircraft builders to put in engines they will fly their family and friends behind. I am firm enough on this point that I will not allow anyone to bring a Chinese crank to a College.  I am not Jack Kevorkian, I do not assist people in ending their lives. -ww

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