The Allis-Chalmers 8070 arrived near the end of the orange era, and the pump that fuels it is a piece of history too. The American Bosch Model 100 brought the single-plunger idea into the 1970s and kept it working through the end of an era.
The Model 100 is a single-plunger distributor pump for medium-horsepower diesels, best known on the Allis-Chalmers 8070. We test it, rebuild it, calibrate it on the bench and send it home ready for field work.
Also Known As
Owners and parts counters call this pump:
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American Bosch Model 100, or AMBAC American Bosch Model 100
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“American Bosch 100 pump”
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“Allis-Chalmers 8070 injection pump” or “Deutz-Allis 8070 injection pump”
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Plate codes starting with 100A, such as 100A9486-6
Did You Know? American Bosch presented the Model 100 to the engineering world in a 1970 SAE technical paper. A decade later it was fueling the Allis-Chalmers 8070, which carried on as the Deutz-Allis 8070 after Allis-Chalmers sold its farm business to Deutz in 1985.
How the American Bosch Model 100 Works
Picture a single bartender serving a crowded counter. One plunger does all the pouring, turning to face each cylinder’s outlet in order and giving each one a measured shot.
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A cam drives the single plunger to pump fuel to injection pressure.
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The plunger rotates, so its distributing port lines up with one outlet at a time.
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A metering control sets how much fuel each stroke delivers.
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The governor adjusts that metering to hold engine speed as the load changes.
The details differ from the older PSB, so a Model 100 needs its own parts and specs.
Shop Talk: “Single-plunger distributor” means one plunger serves every cylinder. An inline pump, by contrast, gives each cylinder its own plunger.
What It Fits
| Make and model | Engine | Years | Notes |
|---|---|---|---|
| Allis-Chalmers 8070 | Allis-Chalmers six, 426 cu in | 1982 to 1985 | Pump code 100A9486-6 |
| Deutz-Allis 8070 | Same engine | 1985 to about 1988 | Built after the Deutz takeover |
| Other Allis-Chalmers tractors | Allis-Chalmers diesels | Check the plate | |
| Other medium-horsepower diesels | Various | Ag and industrial |
Part Numbers We See
Model 100 plates carry a code that starts with 100A, such as 100A9486-6 on the Allis-Chalmers 8070. Tractor makers added their own numbers; one parts supplier cross-references the 8070 pump to 74036809.
Send us a clear photo of the plate and your tractor’s serial number, and we will confirm the calibration.
Owner’s Tip: Before you blame the pump, put a gauge on the fuel supply side and check transfer pressure against your service manual. A tired lift pump or plugged filter starves even a perfect injection pump.
Why Model 100 Pumps Fail and the Symptoms
Most Model 100s have decades on them, and age shows. Water and dirt wear the plunger and its head. Governor parts wear, seals harden and gaskets weep. Tractors that sit between seasons can varnish up inside.
Common symptoms:
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Hard starting, especially cold
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Low power pulling tillage tools
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Black or white smoke
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Hunting or surging at steady throttle
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Fuel leaks around the pump body
Bench Notes: Because one plunger feeds every cylinder, wear in a Model 100 tends to show up everywhere at once. A weak single-plunger pump is weak on all six.
What We Do to Your Model 100
| Service option | Typical evaluation or service scope |
|---|---|
| Test and report | Bench test as received, written results and a service recommendation |
| Rebuild and calibrate | Teardown, cleaning, plunger and head inspection, worn parts and seals replaced, bench calibration |
| Exchange (when available) | Ask whether a compatible exchange unit is available and how the core process works |
What Model-Specific Verification Can Document
Evidence for AMBAC American Bosch Model 100: When an approved procedure exists for this exact component, useful documentation can distinguish identification, visible condition, observed wear or contamination and supported functional test results. Record the assembly number and available engine data before deciding which checks will answer the reported complaint. Bench findings cannot replace the engine-side diagnosis. See how pump testing is evaluated.
Repair Options and Technical Considerations
Repair decisions depend on the exact pump, its condition, the components required and the service approved after evaluation. Ask about any available exchange options and review the service scope before authorization. Plunger and head condition and parts availability determine which service options are technically appropriate.
How to Ship Your Model 100
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Photograph the plate and the pump on the engine.
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Note the tractor model and serial number.
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Drain the fuel and cap every fitting.
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Bag the pump and pack it in at least 2 inches of padding.
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Complete the mail-in form, include a copy and ship to the address provided during intake with tracking.
Ship It Right: Leave the drive gear and linkage as they came off, and tell us on the form if anything was removed. Missing pieces slow everything down.
Related Pumps and Parts
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AMBAC American Bosch PSB, the earlier single-plunger pump on vintage tractors and the M35A2
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AMBAC American Bosch Model 50 for Onan military generators
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All AMBAC American Bosch pumps
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Injector repair
FAQ
Is the Model 100 the same as a PSB?
No. Both are single-plunger pumps from American Bosch, but they are different designs with different parts. Match the plate code.
Can a Model 100 still be rebuilt?
In most cases, yes. We will inspect the plunger and head and confirm the service scope before approved work begins.
Do Deutz-Allis 8070s use the same pump as Allis-Chalmers 8070s?
The tractor carried on with the same engine after the Deutz takeover, but check the plate code to be sure.
Should I send the injectors too?
If the tractor smokes or knocks, yes. A fresh pump cannot fix a dribbling nozzle. See injector repair.
The 8070 was built to pull, and it still can. Share the pump details and find a practical route back to the field. Start a Mail-In Repair or request a repair evaluation.