That is a loaded question for me, since everyone knows or most everyone, I tend to be biased towards the 507. Each of the stoves have their pluses and minuses and each have their own set of quirks to running them. So, for right now I will do a very short summary as unbiased as I possibly can. I can write volumes concerning the two stoves and would if someone really really wanted me to.
The quality of material used to make both stoves are good. I have seen stoves from both manufacture that had been beaten over and over again, yet they were still running. They looked like hell, however, they were running. Both stoves can burn a variety of coal sizes. . . pea, nut, and stove coal and egg coal in the Chubby Sr. Burning pea in the 507 is easier than the Chubby. I currently have my 507's burning stove coal. I believe the 507 is more efficient at burning coal than the Chubby especially when burning nut or smaller coal. The Chubby burns the stove coal more efficiently than the smaller stuff. The Chubby Sr performs very well on stove coal, just remember to put a thin layer of nut on top of the stove coal. It is not needed but helps.
The 507 is much easier to control the burn than the Chubby. This is due to a completely sealed stove. Close the air intake and the stove will flame out. On the Chubby the bypass valves, entry point for the shaker handle and air intake leak air. Once you know how your Chubby acts it is pretty controllable and predictable.
The shake down of the 507 is clean and neat with no dust outside the stove and it does not require poking or slicing. The Chubby requires poking and slicing every so often. The Chubby is very quick to shake down with no problems with the grate where the 507 takes longer to shake down due to the slow rotation speed of the grate. The 507 will sometimes have coal lodge under the grate, lifting it up away from the gear. At this point using a screwdriver is required to turn the grate to clear the grate. Removing the ash in the 507 is much better than the Chubby. The ash pan is never hot and can be removed with bare hands while the Chubby is always very hot requiring gloves and then it is still hot.
Obviously the Chubby has a slight lead in the amount of heat the stove can produce and amount of coal the stove can hold. The Chubby is rated for 70,000 BTU while the 507 is rated at 42,400 BTU. The 507 seems to radiate the heat better than the Chubby. The Chubby Sr with factory blower can really produce the heat. The 507 can be ran at a max temp of 932 F (its like a nuclear power plant going critical) while the Chubby is not recommended to be pushed beyond 700F and burning at this temp for extended periods is not recommended.
Repairing the two stoves is the area where the Chubby has some great pluses. First, the owner Larry Trainer is great to work with and a really nice person. He is now producing the stoves again and has parts for the Chubby Sr. If you damage the body of the stove, just weld it, grind it smooth and repaint. The pot is replaceable as are the grate and any other part for the stove. Larry will ship parts almost immediately. The 507 is not in production any longer and getting parts for the stove gets harder every year. Repairing the case of the 507 can be done, however, with the enamel paint you will never have the same look. You can not purchase any of the 507 case parts new, just used if you can find them. The company that produced the fire brick is still in business and will sell you brick for the 507. Some of the 507 internal parts seem to be no longer available.
I can keep going on and on but I will stop here. If anyone has any questions I would be happy to answer them. In summary and closing. For me the 507 is a real bad to the bone performer. I have burned my 507's for many years 24/7/365. One winter I only had the one 507 and, if I remember correctly, pushed the stove to a burn temp of 875 F the entire winter with the only damage being the cast burn plates above the brick. I burned coal against them which ruined them. The Chubby can take a pounding as well. I have pushed a Chubby Sr to 750F for over thirty day straight trying to keep my shop warm in -45F temps. No damage to the stove, however, Larry told me it probably has shortened the life of the grate and burn pot. Both stoves can an do perform very well. I like the looks of the small foot print of the 507 and the nuclear rated heat it produces out of such a small frame. The 507 can hold its own against, in my opinion, any stove on the market. The Chubby stove without the factory installed blower system falls below the performance of the 507 even though it produces more BTU. It just doesn't radiate heat well. The Chubby Sr with the factory installed blower system is another story. It has the ability to out perform the 507 on the coldest days due to its increased capacity to produce larger amount of heat and move that heat out of the stove through its very efficient blower system. I would never purchase a Chubby Sr without the factory installed blower. If you keep in mind what each stove was designed to do and area it was designed to heat, each stove has its place. Both stoves are solid performers in their own respect.
I currently have four Chubby stoves. Two Chubby Sr's with factory installed blowers, one without and a Chubby Jr. I have too many to count 507's which include two currently online (one red and one green) and a large number of other coal stoves I have gathered over the years. I keep four 507's on display in our family room /coal museum and three of the Chubby's I own. One of the Chubby Sr's (blower model) currently is connected and heating my shop when needed. The rest are neatly put away in storage. I now rotate stoves I have in my collection in the shop so I can enjoy them. I made the mistake this spring on passing on purchasing a stove your father produced. It was in like new condition, however, the distance I had to travel to get it made my decision not to purchase it. I should have driven the distance. I will have one just give me some time. I'm going to stop now before this post crashes the system for being too long. Remember think snow.
Last edited by the snowman
on Wed Sep 18, 2013 12:26 am, edited 1 time in total.