The A-26B/A-26C/JD-1 was equipped with the R-2800-27, R-2800-71 and R-2800-79 and the Hamilton Standard 3 blade 12'6" prop. All three engines were "B" series R-2800s. Visually the most obvious characteristic of the R-2800 "B" series was the one piece magnesium casting used for the nose case (eg, P-47D, F4U-1, F6F, B-26 Marauder, P-61, PV-1.) This was a rounded cone shape single piece casting as opposed to the later "C" series engines which featured a multi-piece round nose casing that was bolted together (eg F4U-4/5/7, F7F, F8F, P-47M/N.) The "B" series can also be identified by the cast cylinder heads, as opposed to the later "C" series that had forged cylinder heads. Visually the "B" series cylinder had cast cooling fins that featured a characteristic "L" shape where the top of the cylinder met the cylinder barrel, whereas the "C" series forged cylinder heads had a large number of tightly machined cooling fins on the cylinder barrel that met separately machined vertical fins at the top of the cylinder. While hard to describe, once you see the two types of cylinders you will not confuse them in the future.
The primary differences between "B" series engines (at least from the front), were the various types of ignition featured.
The R-2800-27 was built by Pratt & Whitney. The magneto for the -27 was a Bendix Scintilla DF18LN mounted at the upper most center drive pad on the nose case. On either side it was flanked by the two round distributors mounted to the top of the nose casing. The -27 used the Scintilla "tubular" ignition harness that was filled with dielectric gel, that connected to the individual spark plug wires...with two plugs per cylinder.
The R-2800-71 was built by Ford Motor Company at the new River Rouge plant and was similar to the -27 except for the GE Tubular ignition harness. The R-2800-79 was also built by FMC and was similar to the -71 but had a different carburetor. The -71 and -79 both featured GE magnetos that were called "turtleback mags" or "mouse ears" magnetos that had distinctively shaped cast covers. The GE system incorporated both functions, the magneto and the distributors, into one self contained assembly, so the center pad on the nose case that was used for the magneto on the Bendix system was redundant so a simple blanking plate was installed. The two magnetos are identical and interchangeable. It appears to me that the majority of A-26B/C Invaders were equipped with the R-2800-71/79.
Be very, VERY careful look at photos of "warbirds". More often than not, they have had their correct R-2800 engine/ignition configuration changed. Most often it was to simplify maintenance and use more common post-war parts from civilian models of the R-2800. I would only use period photos as reference material to identify specific components on the aircraft you are modeling.
Your user name and password will give you full posting privileges to all of HyperScale Forums.
Please note the following conditions of posting:
All contributions are welcome but please refrain from political or abusive comments, racially or religiously offensive remarks, swearing (including the thin disguising of swear words with asterisks and other characters), insulting language and crude metaphors. Please do not use Plane Talking as a public platform to complain about retailers or manufacturers (about issues such as broken or missing parts) before you have followed all normal channels to resolve any greivance. Plane Talking is not the place to conduct personal feuds or for posting personal attacks. Please do not post in capital letters only, as this is considered to be shouting and therefore impolite. Also, please do not post in 'texting message' word format. Any posts breaching these guidelines will promptly be removed from the server and the offender may be excluded from further posting to the HyperScale Forums. Off-topic posts may also be removed from the server.
In addition, Plane Talking is not a forum for the public criticism of the models that appear as Galleries or Articles. Please make any suggestions for improvements or criticism direct to the author via the email link at the bottom of the Article.
Finally, please note that this Discussion Group is privately operated and that I reserve the right to delete any post or cancel any registration for any reason whatsoever.