Allison V1710 E verses F type

[MIflyer]

The C series is different in other ways besides the long gearcase. My friend Ward Duncan, who was the maintenance chief of the 9th PRS in India, said that among their equipment was a V-1710 with a different liquid cooling connection. He suspected they took a C series, put a short gearcase on it and shipped it to them.

 

[ThomasP]

I may be wrong, but I do not think a E or F series reduction gear case can be swapped for the long-nose C series reduction gear case. The pictures I have do not show the bolt patterns without the gear case in place - but the bolt patterns, number of bolts, and the bolt sizes all appear different to me.

Maybe someone has some good photos or diagrams?

 

[MiTasol]

I do not know if the long nose case will fit but the engine starter must be changed for opposite rotation engines

 

[Piper106]

I may be wrong, but I do not think a E or F series reduction gear case can be swapped for the long-nose C series reduction gear case. The pictures I have do not show the bolt patterns without the gear case in place - but the bolt patterns, number of bolts, and the bolt sizes all appear different to me.

Maybe someone has some good photos or diagrams?

Look at the drawing on page 235 of "Vee's for Victory!" by Dan Whitney. On the C series engines the 'accessory' drive shaft comes off the propeller drive gear. Replace a C series nose case with a E series adapter, and there is no drive to the camshafts, distributors, and supercharger, a totally non-functional engine.

The drawing on page 345 of the same book shows how the E and F engines get the drive to the cams, distributors, and supercharger off the other end of the engine.

 

[GregP]

But still, only one part has to be changed in the engine. Which is what Ward Duncan said.

In contrast, when they rebuilt that XP-82 they were very lucky to find a suitable left turning Merlin engine. I rankled some people I guess when I pointed out that for the Merlin you needed a Completely Different Engine for the left turning installation. In aircraft maintenance terms a V-1650 that turns the other way is a different part number and nothing can be done in the field to change that. The fact that it has a lot of parts in common with the other more common engine does not matter.

Actually not true. I worked in an Allison shop for 3 years. In that time, we built up 13 Allisons. A couple were left-hand turn engines, one for a P-38 and one for a Russian aircraft. I say "we," but the main guy was Joe Yancey; his shop and his expertise. Joe DID build a LH engine for a Russian Il-2. It is in Paul Allen's museum in Everett, WA.

There is an idler gear that has to be added. It makes the camshafts turn in the same direction as a right hand engine when the crankshaft is turning the other way. So you did NOT have to change magnetos because the camshafts turn the same direction for LH and RH engines. In the LH prop rotation drawing above, it is labeled "K." That is one part that is different between LH and RH engines.

You have to flip the crankshaft, but nothing on or in the crankshaft changes ... it is the same for LH and RH engines.

You need a starter that turns the other way. That is the second part that must be different. The starter also requires a starter slip gear that goes the other way. That's the third part that is different.

You need a completely new wiring harness because the crankshaft was flipped, so the middle two throws go the other way and the two inside cylinders (cylinders 3 and 4) swap ignition wires. That is part number 4 that is different. If you don't change ignition harnesses, the engine will spit and sputter when you start it, and you will NOT be able to make it run smoothly because the center two crank throws will not be timed correctly.

In point of fact, it is trivially easy to make either a right or left hand turn engine if you are starting from parts and building an Allison up. But, if you have an operating right hand engine, you have to disassemble it and flip the crankshaft to start to CHANGE from right to left turn, and add the parts above. Not especially difficult, but it is time-consuming. Takes probably 2 - 3 days with 2 people doing the work in a clean room. You COULD do it all mostly in one day in an emergency, but it is far better to have spare left-hand engines than to build them up as you need them. The P-38 is the only airplane that normally uses a left-hand Allison, so if you have spare right-turn engines for your P-38(s), you SHOULD have the same number of spare left-hand engines.

I'm not guessing this, I have participated in building them up from parts, borke them in, and saw them fly.

 

[BarnOwlLover]

Actually for a "handed" Merlin, you need an idler gear in the reduction gear arrangement to get the prop to turn the other way. Problem is though the engine's crank turns the same way, you need a new reduction gear casing and associated parts (engine block and crankcase) to fit the new reduction gearbox assembly.

Even though the engines are mostly (key word mostly) the same, the USAAF/USAF did identify handed Allisons or Merlins with different code numbers. The F-82E/F/G/H's engines were -143 and -145. The XP-82/F-82B's Merlins were I believe -21 and -23.

Interestingly, Rolls-Royce did make handed Peregrines for the Westland Whirlwind, but forwent that with the Merlin until the de Havilland Hornet and, though Packard, the F-82.