Getting a ’27 Hupmobile Ready to Tour
It Went 10 MPH…Which Was OK Since the Brakes Didn’t Work. Time for a Tune-Up, Brake Work & Fuel System Check.
THE OWNER COMPLAINED that “it only goes five or 10 miles an hour with no power, and the brakes don’t work.” Yet the car had been “fully restored” mechanically and cosmetically. The engine and the brakes had been “overhauled.”
This collector vehicle is a 1927 Hupmobile equipped with a six-cylinder flathead 196-cubic-inch engine.
Here’s how we “tuned it up,” adjusted the brakes, and otherwise prepared this Hupp for touring.
The tune-up involved servicing the starter system and the ignition system, re-gapping the points, adjusting the timing, testing the fuel supply (vacuum tank) system, and servicing and adjusting the carburetor.
The starting system: The battery was just a year old, had been charged up overnight, and was holding a full charge at 6.5 volts. The battery voltage dropped to 5.5 volts while cranking for five seconds. The ground circuit measured 0.1 volt while cranking.
The 6-volt starting system performs very well for a 1927 Hupp!
(My Web site, Milttheinstructor.com, includes some technical tips on 6-volt system service and voltage measurements.)
Engine condition: Even though the engine was newly overhauled, with only a few miles on it, the oil was changed. We did this to make sure there was no water (coolant) in the crankcase oil.
Coolant found in the oil is an indicator of cracks in the block and/or head gasket leaks.
The cranking compression in PSI measured 75-#1, 80-#2, 80-#3, 80-#4, 80-#5, 86-#6. Again, very good on a newly overhauled engine. This is good enough for a successful engine tune-up.
At this point, the sparkplugs were “read.” The inner porcelain on each plug looked tan to white, indicating a slightly lean air-to-fuel mixture.
Sparkplugs and ignition service: The sparkplugs were replaced and the distributor was serviced.
New sparkplugs were gapped to specification, (0.025 inch) and installed. The new sparkplugs ensured us there would be no “foulers” upon startup. The engine had sat for many years since its overhaul.
New plug wires were installed during the overhaul and measured out at 0 ohms (continuity). This confirmed no open circuits, resulting in good spark right to the spark plugs.
The sparkplug wire firing order was correct (153624).
The distributor location was marked; it was removed and serviced.
Look at the Points…
The first clue to the “no power” condition was that the points had “closed up” to a 0.010-inch gap. This close gap retards the ignition timing advance and burns the points. The point gap specification is 0.015 to 0.018 inch.
There was no cam lube on the cam lobes. This condition leads to early rubbing block failure.
The distributor primary wire is routed through an insulated stationary point contact. The contact point “ground” is in the spring-loaded contact point, rubbing on the distributor cam lobe. (See Photo 1.)
All this checked out electrically. The primary wire insulation measured 0 ohms (continuity) with the points closed, and “infinity” (over 20 million ohms) with the points open. This proved the distributor primary insulation was OK with no “short to ground.”
In order to service the mechanical advance, the distributor plate and the upper cam lobe shaft were removed. There was no oil on the shaft. However, it was rotating freely with respect to the distributor shaft.
The mechanical slots and pins operated smoothly.
All the advance “innards” were lightly oiled with motor oil and reassembled.
(See Photos 2 and 3 for service notes.)
New points were installed, squared up, and gapped to 0.018 inch. The gap was the same on all cam lobes. This results in equal cam dwell on all six cam lobes. Further, the engine will idle smoothly with even compression, correct base timing, and the correct air-fuel mixture.
The distributer was reinstalled with the rotor in the same location. The distributor body was also rotated to the same location and clamped.
After distributor installation, the spark was tested. Using “chicken pliers,” hold the distributor end of the coil wire 1/4- inch from ground, turn on the key, and crank the engine for five seconds. The spark should be crisp and blue with the coil wire 1/4-inch from ground. Our Hupp produced a 1/2-inch blue spark.
Checking Out the Fuel System
The carburetor is a Stromberg model OE-1. It was removed and disassembled. The “innards” were cleaned and the float was tested for leaks by submerging it in hot water and checking for bubbles.
The main jet adjustment was closed up and found to be only 11 ⁄2 turns open from the closed position. The main jet specification on this carburetor is 23 ⁄4 turns open from the closed position. This was our second clue to the “no power” complaint because of the moderately lean mixture adjustment.
There was Teflon tape around the fuel inlet connections. This is a “no-no.”
Teflon tape, if improperly installed, can “creep” inward into the needle valve and will cause carburetor flooding. The Teflon was “picked out” of all the threads.
Upon reinstallation of the carburetor and fuel lines, the threads were sealed with Permatex Thread Sealant, which is item #57214.
How’s It Running?
Startup: The engine was cranked, choked and started. It was “stuttering” at first. The advance lever was advanced and the main jet was adjusted to a slightly leaner position from the specified 23 ⁄4 open position. The RPM increased and the engine began to run smoother.
The idle mixture was adjusted to halfway between lean and rich. This is the best mixture for smooth idle performance.
Generally, in order to establish the best mixture position, open the idle adjustment screw until the engine stumbles due to a very rich mixture. Then turn the mixture screw in slowly, listening for an RPM increase and smooth running. Continue turning the mixture screw inwards towards the lean position until the rpm “drops off.” This is the lean point. Then adjust the mixture to halfway between the rich and lean positions.
About That Steering Box…
Lubrication: The steering linkage had been lubricated with grease at all the grease fittings.
The steering gear box was dry. It was filled with 85-140 weight gear oil but we found that it leaks very slowly. There is no cross shaft seal.
Taking a Test Drive
After the tune-up was completed, the engine started within five seconds when cold. When it was warmed up, it would start within one second from beginning the cranking.
A short test drive was made and the main jet and idle mixture were slightly readjusted as outlined above. The engine surged slightly under load, going uphill.
Some additional tuning checks will be rechecked after adjusting and repairing other systems (the brakes.)
The oil pressure gauge was pegged at 45 psi, the water pump was noisy and leaking, and the generator was charging at over 40 amps! The generator was leaking oil out the front mounting plate. These systems were checked, serviced and adjusted…after the brakes were adjusted.
Adjusting the Mechanical Brakes
During the road test, this Hupp would barely slow down when we applied the service brakes.
The pedal travel was about 2/3 of the way to the floorboard before the brakes would begin to operate. Obviously, a very unsafe condition.
This Hupp is equipped with external brake bands on the rear axle and “3 shoe brakes” on the front. The front brake levers were tilted around 25 degrees toward the rear of lever rotation.
No wonder it took “300 yards to stop.” The front brake lever was way out of adjustment. The rear brake lever angles were OK, but the adjustment of the bands was very loose.
The general procedure on all makes for adjusting mechanical brakes requires disconnecting the brake rods, removing the drums to check for internal linkage binding, checking the brake lining condition, adjusting the brake shoes to fit the drums, checking the operating lever angles, and adjusting the brake rod or cable length to fit the levers.
On this Hupp the brake operating levers, pivot point and adjustment threads were lubricated with WD40. The brake rod clevis threads were cleaned up with dies and taps and lubricated. All this “maintenance” is very necessary to ease the labor effort during major brake adjustment plus all the brakes will operate equally as new.
With the brake rods disconnected, the rear bands were centered and adjusted to 1/64-inch clearance around the drum circumference. The rear brake operating levers were at the correct angle for easy operation and mechanical advantage to lock the drums.
Next, the front wheel drums were removed. The “3 shoe” adjustment and the brake shoe centering bolts were cleaned and lubricated.
The front operating lever cross shafts were cleaned and lubricated. The brake shoe operating cam was cleaned with solvent and lubricated (very light film) with general purpose modern moly grease.
Operating the external lever with the brake rod disconnected resulted in easy and correct operation of all the shoes on the front brakes.
After installing the drums, with new grease in the wheel bearing, adjust the wheel bearings castellation nut to just before minor drag (preload). This is essential so you can “gauge” the brake lining contact drag during adjustment.
With the brake rods temporarily connected follow the brake shoe adjustment procedure in the reference manual listed at the end of this article.
Loosen the upper locknut. Adjust the shoe adjustment pointer downward until the brake shoe locks the drum during hand rotation of the wheel. Back off this adjustment (moving the pointer upward) until the drum turns free. (Around 3/8-inch at the pointer tip.) Lock the adjustment pointer nut.
Then, loosen the bottom two shoe cam adjustment jam nuts so the brake shoes will move to “center up.”
Recheck the upper shoe adjustment by moving the pointer downward until the drum has a heavy drag. Back off this adjustment (raising the brake pointer upward) until there is a light drag on the drum. Lock the pointer jam nut.
Now that the front brake shoes are adjusted properly, it is time to check both front brake lever angles. In all mechanical brake systems, the lever angle must always be positioned ahead of the lever rotation pivot with the brake pedal off.
When pushing the pedal down to apply the brakes, the brake lever must be near vertical for correct braking. The advantage of these requirements is you gain maximum mechanical advantage when applying the brake pedal.
If the mechanical advantage (lever angle) is incorrectly adjusted, mechanical brakes don’t work.
Unfortunately, the Hupp reference manual does not outline the front lever angle specifications.
On our Hupmobile, the front brake operating levers are splined to the brake operating cross shaft.
Loosen the clamp bolt and nut and tap lightly to slide the lever off the cross shaft. Reposition the lever on the spline until the clevis end of the lever tilts forward around 3/8 of an inch forward of the brake lever pivot point.
Then, have a helper push the brake pedal. With a heavy drag of the wheel, the brake lever should be near the vertical position or it should just tilt forward slightly. This lever position on the front brake will provide the best mechanical advantage for effective stopping (like locking up all the wheels in a panic stop at 30 mph).
Perform the same front lever adjustment on the other side. Test the opposite brake and make sure that the lever angles are equal.
The trick is to have the same mechanical advantage on both front wheels.
After getting the front levers adjusted to the same angle, adjust the brake rod clevis length to fit the levers with the brake pedal in the up position (with the foot off the pedal).
We adjusted the brake rod length of all four rods until we achieved the same moderate drag on all four wheels with the brake pedal depressed two inches.
On our Hupp we did not adjust the “rocker shaft.” The rocker shaft is the main cross shaft connected to the brake pedal and all four brake rods.
Results: All four wheels now locked up at 30 mph, and the car stops straight. We’d say that’s at least somewhat better than taking 300 yards to stop at 30 mph.
Minor Brake Adjustment: Subsequent to the above major brake adjustment, I advised the owner to drive the Hupp for 100 miles, and then perform a “minor” adjustment. The brake lining will now (or should) be worn enough and seated.
The minor adjustment will consist of adjusting the front brake upper pointer downward to a heavy drag and then pushing the pointer upward until the front wheels drag lightly (with the foot off the brake pedal).
The rear brakes (external type) may require tightening the adjustment nut a couple of clicks “equally” on both sides.
Then, depress the brake pedal two inches and check for a moderate equal drag on all four wheels.
If there is variation right to left or front to back, adjust the backing plate adjustments for additional drag. Usually, this requires only a slight adjustment.
Do not change the front rod lever angle, the rear brake lever angle, or the brake rod length.
Ancillary Systems Service & Repair
Water Pump: The water pump was leaking at the packing gland. It was removed and professionally rebuilt. A new shaft was machined. A new bearing was installed. New packing was installed for the shaft seal. After installation, the packing gland was tightened just enough to stop the dripping.
Oil pressure: As noted earlier, the oil pressure was pegging the gauge. The relief valve was adjusted in accordance with the Hupp manual. The manual instructs one to remove the relief valve cap and turn the adjusting screw inward (clockwise) in the cap. This relaxes the relief valve spring, resulting in less oil pressure.
On our Hupp we turned the screw inward four turns. This brought the oil pressure down to 20 PSI when revving up the engine in neutral, simulating 20 MPH.
Generator: The generator was charging way too much (around 40 amps at 30 mph). The Hupp manual recommends that the gauge show a slight charge rate with the lights on (bright) at 20 mph. this is around 15 amps.
This generator is a “third brush regulation” generator equipped with a cutout relay. As discussed above, the generator was charging at over 40 amps. Upon disassembly, the armature was purple, indicating it was running very hot.
The generator was professionally reworked. The armature “growled” OK and the fields tested good. The commutator bars were good enough and did not need re-machining. New brushes were installed.
On the car, with the engine off, the third brush plate was rotated opposite generator rotation to reduce the charge rate. After adjustment, the gauge showed 10 amps with the engine revved up and the lights off.
Cooling: Unfortunately, during subsequent test drives, the cooling system was losing lots of coolant (water at this time). During restoration, the radiator was “boiled out” and the flow tested around 90% of full capacity.
I advised the owner to try cleaning the cooling system with “Super Flush.” It still lost water. He had the system evaluated for head gasket and block leaks. There were no combustion leaks.
With an 81-year-old honeycomb radiator, it may be time for a modern replacement. New honeycomb cores are available. Try the Filling Station in Lebanon, Oregon, (fillingstation.com). It carries reproduction parts for vintage Chevrolet cars and Chevy and GMC trucks). A new Chevrolet reproduction honeycomb core will fit this ’27 Hupp with minor modifications.
With the mechanicals in “touring” condition, the owners detailed the Hupp so it would look nice for touring as well.
Trying It Out
The owner drove this Hupp on short trips to “shake it down” for long trips. He now feels more confident for longer trips.
Hupmobile Instruction Manual, six-cylinder—Series A; Maintenance Manual, Hupp Motor Car Corp.
Note: The above tune-up, brake adjustment procedures, and references are generically applicable to all makes of vehicles. I urge you to obtain the owners manual or the service manual for your make and model. Try contacting national marque clubs for your application. Also try used book stores, literature swap meets, and/or Internet search engines.