MM BF restoration-got Hercules engine running



Super Member
Jun 4, 2005
Getting old. Sold the ranch. Sold the tractors. Moved back to the city.
It's been a while since I've had time for this project (now going on 4 years effort). The Hercules IXB3SL engine has been on a run stand (a modified Harbor Freight engine work stand) for nearly a year (4 cyl, 25 hp, L-head similar to a Ford 8N engine). Engine has been completely rebuilt (zero compression on 3 of the cylinders when I got it home after buying it from a local seller).

The rebuilt engine was so tight that the 6 volt/positive ground starter could barely spin the flywheel. So I changed to 12 volt/negative ground, kept the 6 volt starter, replaced the starter solenoid with a 12 volt unit, installed a 12 volt ignition coil.

Here's what happened on the first startup.

Hercules engine run no 1 29jun2012 - YouTube

Notice the lowest of the three gauges. It's reading oil pressure and showing about 45 psi--pretty good.
I used one of those spark plug whistles in cylinder #1 plug hole to find TDC on the compression stroke (really takes the labor out of that task). Lined up the timing mark on the flywheel and made sure that distributor rotor was pointing at spark plug wire #1. I checked all the plugs with one of those in-line neon bulb gizmos to make sure all four plugs had fire. The float on the Marvel Schebler updraft carb was sticking so I had to disassemble and reassemble the carb. That and a few taps on the carb bowl with a cresent wrench cured the sticking problem.

I closed the choke completely and cranked the engine with the kill switch in the "engine off" position for a few seconds to get some fuel moving through the carb. Flipped the kill switch to "run", hit the start switch and bingo--we have lift off.

The specs for the head bolts is 420 in-lb (35 ft-lb) which seems way low to me (Ford 8N is more like 65 ft-lb and my 1945 Oliver 60 is 77 ft-lb on the head bolts). I took a conservative approach and torqued to 45 ft-lb and crossed my fingers. Looks OK. I'll hook up engine cooling next to be sure there are not water leaks in the head or elsewhere in the block.

Need to get that BF reassembled to clear some floorspace in my shop. I need to work on my 1951 Farmall Super A next. And I jonesing for a JD B real bad:confused2:.


Elite Member
Sep 14, 2010
Sounds like it is running great. That looks like a nice setup for testing the engine. Can't wait for pictures once it is complete.