The 50/70 is old and slow but it sure packs a punch. Just a little bit stinky though and LOUD.

 

My favorite 45/70 load is a 405 LFN out the muzzle at 1600 fps. My screamer load is a 300 JSP out the muzzle at 2500 fps for almost 4000 ft/lbs of energy. I only shoot Black Powder loads in my 2 "Trapdoors".

 

Just to clarify things for those that are interested. The GAA in my Mustang has been lightened to 960lbs. wet. The 500 HP rating is at the factory governor setting of 2800 rpm. Even bone stock they will make 550-575 with a tweak of the governor.
The Mustang engine was actually built to take lots of boost for use in my pulling tractor, but I decided to keep it naturally aspirated for the Mustang. It's still good for 850+ HP and 1300+ Ft. Lbs. without boost. The factory valve springs are all done by 3200-3400 rpm and are the first thing to replace when modifying a GAA. The stock bottom ends will stay together at 5200 rpm with proper clearances. The intake ports need some modification to really wake the engines up. The Ford GAA engines were really high tech. for 1942. Henry Ford even won a patent for the dual overhead cam's shaft drive system. Working-tuning on these engines is not for the novice mechanic, they take special tools, procedures, and an appreciation of WWII technology.

As for them being slow revving, removing almost 200 lbs. of rotating mass makes a difference. You be the judge.

YouTube - Tank Engine Mustang III

 

locomotivebreath, that's a great setup, and lots of great info

 

Thanks.

By the way Bobsaok has created a small website dedicated to the Ford GAA engine here.
Home

 

My dad drove a tank retriever with that GAA engine, wish I had seen those vids to show him before he passed, but I saw one at the Tank Museum in Danville,VA. with him. BTW how's everyone like that new 572 crate engine Ford has out now? BTW, it's based on the 460

 

You might also want to rethink this statement, the Allison and Merlins ran up above a grand in HP ratings. And a D8 Cat had more than a 300 hp engine, More like 425HP

 

https://www.cat.com/en_ZA/products/n...000001318.html

More like 307hp on the current D8R according to the manufacturer themselves with the 3406. Capable of more? Sure but you're cracking open the governor seal and voiding any warranty.

 

Trucks got the same "Dozer motor" rated at 425HP. I know, I ran with them.

 

D8 does not equal "truck". Cat makes dozens of ratings on the same engine; just depends on the application. I know, been working on them for 27 years.

 

I drove one (3406) turned down to 300 HP for three years. It was a pig. I've been driving for 43 years. Cats, Detroits, Cummins and Macks. Current ride is a 2014 Mack with a 505 motor. It will burn rubber and keep up with cars, red lite to redlite with an empty trailer.