Restoring a 5 HP Hubbard

By Staff
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An old 5 HP Hubbard sat frozen in time for the past 35 years outside our woodshed in Howley, Newfoundland. It survived the worst imaginable Newfoundland weather possible, as well as all the abuse that small kids (big ones, too) could throw at it. This old Hubbard has been in our family for 40 years or more. I remember growing up around this Hubbard. We used it in our 18-foot wooden fishing boat that we used on Grand Lake, Sandy Lake, and Birchy Lake for everything from fishing, hunting, collecting firewood to just going to a beach across the lake for a picnic.

During one of my yearly back-to-Newfie trips in the fall of ’96, I loaded it in the back of my pick-up truck and transported it back to my other home in Ontario for its revival.

Freeing the piston
Getting the Hubbard home was no problem–freeing it up inside was another story. The piston was seized solid because of all the sand and dirt inside as well as 35 years of being exposed to all types of precipitation.

Disconnecting the connecting rod bearing and filling the cylinder with penetrating oil was my first move. Every day for about a month I would go to the garage and poke and prod at the piston and check the oil level. About five weeks later the penetrating oil started leaking past the piston rings. After quite a bit of tapping with a piece of hardwood and a hammer, more pushing and shoving, the piston was free and out it came.

Getting to work
After everything was torn apart it looked in terrible shape–the babbitt bearings were worn out; the crankshaft was rusted, scored and pitted terribly; the wrist pin was sloppy and shimmed with pieces of tin. All the rings but one were broken, and that one had 3/16-inch endgap.

Honing the cylinder was my first chore. I used a rigid hone on my drill press, using a coarse stone to start and finishing up with medium. After all was said and done, I had gone only 0.020 inch over 5.000 inch to clean up the bore diameter. Not bad for 35 years of seizing up.

The crankshaft was sent to a local machine shop to be cleaned up. The throws were ground to 1.569 inches from 1.582 inches and the main was ground to 1.582 inches from 1.622 inches. A machinist friend of mine from a local trucking company volunteered his services to refit the wrist pin. Using the old pin as an example, he fashioned a new one. Then he opened up the old wrist pin holes and bushed them back to the size for the new wrist pin. He did an excellent job.

The piston rings were replaced with 5.000 inches outside diameter hydraulic cylinder rings with step-joint ends. Because of their thickness I had to use two rings per groove. Two rings–5.000 inch inside diameter by 4.625- by 0.156-inch thick were used in each groove.

The new piston rings have step-jointed ends, which gives much better compression than the butt-jointed ones that came out. The rings that came out had half-round grooves in them, which sat over top of pins in the ring grooves to prevent the rings from rotating and catching in the ports. Since I was replacing one ring per groove with two rings per groove, I had to install new locating pins.

The ring gaps were located 180 degrees apart in each groove. New retaining pins were installed in front and back of the piston. The holes were drilled with a 3/32 inch drill bit, and the pins were made of 3/32 inch welding rod.

Material was removed from the step-joint of the piston ring to accommodate locating pin and allow the piston ring to close properly.

The pin holes were drilled from top to bottom for the upper two ring grooves and from the bottom up for the lower ring groove. The pins were driven in whole and cut to proper length afterwards. I found that a 3/32 inch welding rod is a tight fit in a 3/32 inch drilled hole. However, I did center-punch them in place after they were in.

There was about an 0.040-inch clearance in the bearings and the crank-bearing was crumbling and worn out. So needless to say, I melted all this old babbitt out and poured new stuff when the crankshaft came back with its new sizes.

Pouring babbitt
When I poured the babbitt, I installed the crankshaft in both bearing housings and bolted them to the main housing. This maintained a true fit to the housing so that the bearings were poured in line with each other. I had about 0.060 inch lift in each bearing housing, so I shimmed each end of the crankshaft 0.030 inch which centered it at each end. I sealed the ends of the bearing housings with ‘Play-Doh’ (kid’s stuff) instead of real babbitt putty. It worked great! Before I assembled the crankshaft in the bearing housings I coated them with soot from an acetylene flame to prevent adherence of babbitt to shaft surfaces. I melted the babbitt in an old cast- iron frying pan on a Coleman campstove. Rule of thumb for proper pouring temperature was a piece of white pine wood which would start to char and smoke when inserted in the babbitt, but not ignite. The babbitt was poured in through the grease holes which I located to the top for pouring purposes. After the babbitt was poured and everything had cooled, I took everything apart and scraped both bearings to a 0.0015-inch clearance, after which I cut grease grooves in each bearing at the grease hole.

When I took the connecting rod bearing cap apart, I left the old babbitt in the bearing cap and removed what was in the rod half of the bearing. When I was ready to pour the rod bearing babbitt, the old bearing in the bearing cap half assisted in locating and centering the bearing on the crankshaft. Shim stock was placed between both halves to prevent them from sticking together. After the rod half of the bearing was poured 1 removed the old babbitt from the bearing cap, then bolted both halves together on the shaft with the shim stock in between and then poured that half. I used the same procedure for pouring as with the other bearings such as sooting the shaft diameter, sealing the ends with ‘Play-Doh,’ etc. Afterwards I took both halves apart and scraped both halves to obtain 0.002-inch clearance. There is a 0.015 inch shim between both bearing cap halves so that when the bearing wears down, the shims are removed and the bearings are rescraped to obtain desired clearance.

The connecting rod bearing cap bolts were very sloppy and loose-fitting when I took them apart. So I drilled the holes oversize and reamed them to 1/2 inch diameter from 7/16 inch then fitted them with high tensile fine thread bolts. (1/2 inch – 20NF) They were torqued to 55 ft./lbs. and double-nutted.

The connecting rod wrist pin bushing was removed and given 1/4 turn and reinstalled to get rid of sideways movement or ‘slop.’

Finishing touches
The outside of the casting was cleaned up with heavy-duty Brillo pads on an 8000 r.p.m. surface grinder. Some of the smaller nooks and crannies were cleaned up with wire wheel on an electrical drill. After all the old paint was cleaned away it was primer-coated with red primer (brush-on), then painted with red machinery enamel.

I think that every time Mom or Dad did any painting around the house they always cleaned their paint brushes on the old Hubbard out by the woodshed! There was hardly any rust on the outside, but about a 1/32-inch thick layer of paint all over.

All the brass fittings were dipped in CLR Cleaner and buffed with Brasso brass cleaner.

The water pump was packed with rope packing. It was beginning to deteriorate so I replaced it with modern-day 1/8-inch square John Crane packing.

The exhaust manifold was missing so I had to fabricate one. Using stainless steel pipe and plate I fabricated a water-cooled exhaust manifold as shown in the sketch below.

The flywheel was very difficult to remove from the crank shaft. I used my 10-ton hydraulic press and a couple of attempts, using lots of heat from an oxy-acetylene torch, but nothing moved. Before I tried a third time, I drilled a 1/4 inch hole into the3/8 inch square key. This relieved the pressure on all four sides of the key which I later found to be rusted in place. The third attempt with plenty of heat and BOOM!, off it came. After everything had cooled, micrometer readings showed a size-for-size fit between flywheel bore and shaft diameter. It was a square key with a tight fit on all four sides that did all the tightening and locating of the flywheel and shaft fit.

Shaft O. D. 1.501 inches; Flywheel bore I. D. 1.501 inches

The carburetor is an old Schebler that I found in a friend’s woodshed back in Newfoundland. Since the proper check valve was missing and my attempt to locate one was futile, I adapted a 1 inch Crane water check valve. I installed a light spring on the gate so that it would close quickly after the air/fuel mixture was drawn into the crankcase.

It took a lot of trying to get the old Hubbard to run. After adjusting the breaker rod to get the ‘make and break’ at the right time and a couple of shots of ‘Quick Start Fluid’ down the priming cup, lo and behold, it started! It did a dance around the garage floor for a few seconds until I shut it off. I had it mounted on a rubber-tired garden tractor wagon with lots of bounce. After its first ‘dance’ I turnbuckled it down to a couple of steel grids which corrected the bouncing problem.

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