As Brian said, the predator engines are cheap and available (from harbor freight).
Also, I have heard quite a bit of positive feedback about them.
So, that is why I bought one.
As Wallace said, they are probably not built to last.
But, what is, these days?
I believe the one I bought was advertised as 13 HP (420cc).
I am hoping that, by de-rating it to about 8 hp on charcoal gas, I will achieve a good lifespan.
We will see.
Nothing that turns at high rpm can be expected to last too long sadly.
Old tractors are a good source for engines like the B43G.
That being said it will cost you more to rebuild one than you can buy a Predator for.
What is a fellow to do?
Look at what this costs.
http://onanparts.com/index.php?main_page=product_info&products_id=137
I am confident it could make 1/2 its rated power or more at a reasonable rpm of 2200 or so.
And do it very reliably for a long time with care.
But the cost, my god what has happened to the world?
Yes these Onan part are crazy expensive I have a commercial 4500 That needs a AC voltage regulator at about $300 Found a newer ohv unit on craigslist that needs a circuit board @$500-$600. CCK pistons $130 each rings sold separately. I have 2 of these but at 5.5 :1 cr and flat head to boot how well can they do on wood? Steve U made reference to someone successfully doing it I will have to see if I can find that. Sure would be nice to hear one of them chugging along rather than that screaming thing I am using now.
I’ve got an old Onan that I tried to patch up a few years ago.
It works OK now.
But that’s about $1,000 in parts later.
And they weren’t major parts.
That’s why mine are setting now and I am collecting all I can find. Thinking I want to run two 120 volt units with a 4cyl car engine. Run 1 for most of my needs and second when I need 240 in the shop, on wood of course. Baby steps, I gather this stuff as I find it for free, trades or next to nothing. Big plans, little money.
I am thinking the ford 2.3 litre used on the Mustang and Pinto might be a reasonable choice.
Its free wheeling if a valve sticks and much cheaper to buy and repair.
But would it be reliable?
It should be good for 20 Hp at 1800 rpm on wood
Wallace I have had them and 2.0 and 2.2 and 2.5 Chevrolets and personally liked the performance, reliability and fuel economy of the Chevrolets much better. the 2.3 I had was in a Ranger, had a timing belt and over head cam, not sure about the older ones. Mine was a 1990
im always surprised when I get a " puff back " that the top of my engine is still there 
That’s great mike. Had no idea you caught all of that on video. Priceless. 
I was saving it for a surprise!
Apparently, the repairs to the gasifier at Argos were successful.
We were standing around the shop tonight, and decided to improvise a fitting to the new Predator engine.
We hadn’t even unloaded the charcoal from the gasifier from Argos.
A brief inspection of the alumina nozzle with the fiber scope leads us to believe that another crack is developing.
But, we thought what the heck.
At first, we couldn’t get it to start.
Then, we realized that, in our excitement, we had failed to disconnect the blower before trying to crank the engine, and the gas was too rich.
We disconnected the blower, and it started right up.
Man. I really like that electric start.
Anyway, will try to post a short video soon.
EDIT - Here it is.
OK. Finally got all the parts and got the generator put together.
It ended up being:
13 HP Electric Start Predator Engine from Harbor Freight $360
Chicago Electric 7.2 kw running 10 kw peak generator head Harbor Freight $300
1/2 inch plate steel to mount everything on $50
2 4" pulleys and belts (around $50 I think).
Total cost approximately $760.
Got everything assembled this weekend and did the first run from charcoal gas yesterday.
Test went extremely well. Haven’t made any changes to the gasifier since Argos. Still has the same charcoal in it. Lit it up, just barely touched the starter, and the generator fired right up. Tried running various loads including an air compressor, a mig welder, angle grinder, shop fan, etc. It handled all the loads with no problem.
Very pleased so far.
I will paste in the video shortly.
EDIT - Here it is:
I decided to go ahead and empty the gasifier out and check the condition of the nozzle. I expected that it was getting eroded because the heat lobe had moved closer to the front. Sure enough, the nozzle was about shot. I will post more about that in the “nozzle” thread.
I would make the following comments about this generator design:
For my intended application, I could have used a smaller gen-head. However, as it turns out, the harbor freight gen head was cheaper than smaller gen heads that I could source elsewhere.
If somebody really wanted to maximize the output of this setup, especially running on woodgas or charcoal gas, the 22HP V-Twin Predator engine would be a better choice. It could probably achieve full output of the gen head even when derated by 30% or more. However, the engine is about twice as expensive ($700).
Nice set up.
Chris offered a good suggestion about finding a Geo Metro engine for the 10k gen head I have. I have looked in Craigslist and found some for about $200.
Did you load this generator down?
No. Haven’t done any kind of scientific load test. Tried a few pretty heavy loads and it worked fine. But my guess is that this setup will make around 4-5 KW on charcoal gas.
The gen head calls for a 16 HP gas engine to make full rated power. That’s why I think the 22 HP Predator would be about right if trying to make full rated power on charcoal gas.
Kyle, nice job…!! I know this sounds crazy but I pulled my head out of storage 
and plan to belt it up to one of my small clones. It should serve two functions, 1 - generator 2 - flywheel… 
HF online or mailer super coupon this month (July) for $599… still a lot of cash!
The puff-back at argos cracked my filter bucket. The stress cracks have been growing, and I have started sucking air. So, I took this opportunity to do a minor re-design on the gasifier.
I cut the end off the old filter bucket, with about 2 inches of sidewall remaining. I stuck this down into a new filter bucket and RTV’d everything in place. This beefs up the bottom of the bucket, giving it more rigidity.
Then, I changed up the plumbing a little bit.
Since several of you guys have said it is not good to having the hot gasses flowing through your bilge blower all the time, I added a valve and some different piping so that gas goes through the blower only for purposes of firing up and flaring. After making good gas, the valve is closed and flows directly from the filter bucket to the engine, bypassing the bilge blower.
While I had the gasifier apart, I also snapped a few pics of the nozzle and some weird white slag that was forming. See the nozzle thread.
After putting everything back together, we did a test run on the new gasifier / generator setup.
Previous to now, we have only placed comparatively light loads on the generator.
But Hoss wanted to try hooking up our Miller 211 MIG welder to it.
Frankly, I was skeptical. We have previously tried to run this welder on a Honewell 5500 watt generator, and on a brand new Generac 6500 watt indistrial grade generator. Neither of these generators would pull the load.
So, we got a big surprise when Hoss plugged the welder into the new generator It welded pretty good. You could tell it was pulling it down a little bit when he was welding a continuous bead, but it was never enough to bog the engine out.
Very surprising. By my calculations, I did not expect to be making more than about 5,000 watts with this setup on charcoal gas (even though the gen is rated at 7,200 continuous and 10K peak).
Anyway, we were very pleased with these results.
After about 35 minutes of welding, the bottom of the gasifier barrel started getting very hot, to the point where it was glowing red and smoking. I also thought I could see a corona of hot gas protruding from the air intake port. At this point, we thought it prudent to shut everything down.
I am assuming that this is because we were pulling on the gasifier and generator much harder than we ever have before, but I am not sure.
Anyway, I will post some video when I get it edited.
