Firestone 7.5 & 10hp outboards

[jnjvan]

The ’49 Firestones and Corsairs also had the weak cable shift linkage.

JV

[kevinrude]

quote lotec:

I particularly like the unique one-year only 1953 Gold Pennant 7.5 and 10hp models and have owned several. One of the big design oversights with these is the center strip on the cover, it is a PITA to remove, something you must do to work on anything involving the recoil, magneto or carb. This same design was used, after Scott dropped it, on many of the private brand motors through 1958.

Arghhhhhh!!!!!!! And that’s why my ’53 is a saw horse queen!!!!!

[kevinrude]

Not sure if this problem is chronic, but my 5HP Firestone (with center strip on the cover) had some parts of aluminum casting snap off. The aluminum piece that the fuel connector goes in to and one of the threaded holes that accept a shroud bolt. Oh yeah, and the graphics on one side of the shroud are fairly corroded. But it only cost $15. Usually my aggravations cost WAY more than that 😆

[wiscoboater]

I have worked on a few Scotts, Firestones, and their off branded units. They were fast motors I’ll give them that. The build quality of their stuff In my opinion was in the day…equal to what we see out of China today. They were great when new. A few running hours later and not so much. Let the Scott guy hate mail come my way. They were built cheap and not made to last. That is why the company did not last.

[lotec]

quote :

They were built cheap and not made to last. That is why the company did not last.

While I understand where you are coming from, I don’t feel that is a fair statement for all the Scott motors from 1946 to 1969. The motors were not cheap, most had higher retail costs than their competitors and Scott billed themselves as a superior and innovative product. Even the off-brand Firestone and Corsairs were not "bargain basement" items in the early 1950s such as the contemporary Elgin and Clinton motors were. Scott was a small outfit when compared to OMC and, as this post outlines, clearly missed things in their engineering and designs.

Certainly the case can be made that through 1953 they were on par with all the other makers: OMC, Mercury, Champion in terms of engineering, design and quality. (Even OMC had their duds in the late 40s and early 50s – the 3.3 Sportwin, Zephyr and Johnson SD being three that I don’t feel are representative of the bulk of their products) And the Scott motors through 1953 are just as long lasting as any other maker – just go to any outboard meet today and look at all the 3.6, 5hp and 7.5hp ones you can buy and will still run!

When the Bail-A-Matic was introduced it was a big turning point, both good and bad. While it was heralded as a huge innovation and blessing to the huge number of people with leaky wooden boats, (Which was most everyone!), they also tried to keep things light and stay competitive in pricing and that led to castings that were thin and easily broken, flimsy cowls, etc…. Then people started to have service issues with the BAM and that combination definitely hurt their reputation. And we have not discussed that Scott never spent time or money on corrosion resistance, a major shortcoming for those of us on the coasts – the largest majority of boaters. I guess because they were in Minneapolis salt water wasn’t something they thought much about! (I have one note from the mid 50s that they tested in salt water somewhere in Long Island – my guess is the exec’s wanted a Montauk fishing trip!) No doubt this is the era and products that many feel were cheap and flimsy.

Yet at the same time their 3cyl motors were way ahead of the competition in design, something that took 10 to 20 years for other makers to all eventually emulate. But again, a look at the service bulletins Scott issued in the late 50s and early 60s shows that they often used the customer as their design testing program, issues with the electrics, linkages and fuel systems were very common. Having read through hundreds of pages of service bulletins they do not appear to have been out to cheat anyone, they simply didn’t have the testing resources that OMC and (by the 1960s) Mercury had to work out the bugs. And I won’t get into the low-profile Fishing Scott motors since I personally despise them… However, within a few years both OMC and later Chrysler both came out with low-pro motors to match what Scott did in 1960.

As to why Scott/McCulloch didn’t last, a bit of research will show it didn’t have anything to do with the products. Frankly, the bulk of the early 60s Scott products were no worse than their Mercury or West Bend counterparts in quality or engineering. The fact is that Bob McCulloch (and the company directors) simply lost interest in that part of the company. He ended up making more money in the oil business and with his land development of Lake Havasu, than he ever could dream of making in outboards. It is obvious that by the mid 1960s they simply let Scott die on the vine – moving London Bridge became the focus and not building outboards – even the power equipment line started to fade then. Too bad because there were some interesting and highly innovative outboard products in the wings like the Ox diesel and the unusual R-120 supercharged radial. Seen the info on the new Mercury diesel?

[jeff-register]

Lotec,
First, Thank you for the reply. My first outboard over thirty years ago was a 1953 Firestone 7.5HP. I had no idea how to performan service although I had many hours on other mechanical devices such as the Chevy Corvair & many others. It flooded, jumped out of gear & overheated.
I was pleased beyond belief, a challange for sure!!
Lets see where did I start? Oh yes it leaked more oil than it held.
I will start with the gearcase, That took several tries. The Driveshaft needed filled with brass & polished, the stainless impeller housing was groovey & replaced along with impeller. The stainless housing required heat to loosen from the aluminum casting, but no installation of seals yet! I had a friend double machine the case so I had one seal up & the other down to keep water out & oil in. Then came the aluminum pipe that I pulled from the aluminum casting to discover an old dried out 0-ring for a seal that forgot how to seal moons ago. I replaced the o-ring & aluminum pipe & before I installed the shift rod I cut a 6" piece of blood pressure cuff tubing. This tubing has less density & will fit over the shift rod (aluminum tubing) & the shift rod itself. This made a very nice flexable tubing shift shaft sealing tube. Now for the nice gears & shafts! That took a few parts motors to find a set. Next came the front cover leaking. I cut my own good gasket material & used a small straight edge across the gasket face machining & found them to be pulled up where the threads were. Filed them flat again. I cut the gasket to fit & left it oversize on the outside edge. I replaced the hardware with Allen head capped finish hardware & outside star washers & S.A.E. flat washers & very small o-rings for sealing. The prop shaft needle nose bearings needed replaced the prop shaft prop end bearing as well1 To finish it off a new bearing & seal too. I held it in place & put it all together.
There is more I did to the throttle & magneto but I was tired!!
Jeff

[billw]

Art, thank you very much for the big write-up! I enjoyed it very much, even though the only applicable motor I own is the split-top Firestone 7.5!

Long live American manufacturing!

[gjonz]

I have a Firestone 7.5 hp I’m finishing up, but the lower shroud that the tiller is attached to is cracked in half. My welder said when he tries to weld it…it just melts regardless of what he tries.

But maybe someday I’ll be able to find one and get her on the water. I actually want to do a full cosmetic restore as well, but right now she lays in the garage silently waiting.

Sigh!

Love the look of those early Firestones with the "Buck Rogers " tank.

Greg

[20mercman]

I have a 1956 Corsair Navigator 7.5 hp. with the center strip cover. It is a bit of a pain, but after you spend much time working on MK-25’s, you will think the Scott cover is a snap. This has so far eluded us from having it in a fully serviceable condition. The main problem I have now with it is that it is cutting out when getting warm. I have been convinced it was overheating, but every video I see of these running, I see the same thing….steam coming out the back at times. Perhaps these just run hot! I honestly have not spent enough time lately on it as there has been other projects to finish first. I was going to look into new condensers and try again. This has a lot of power for a 7.5! Other Scotts we have are 50, 55,& 57 3.6hp’s and a 68 14hp "Sears".

Steve

[jeff-register]

I don’t think it will stay in place either. Mine has filled from storage & guessing wear letting the 90 wt gear oil in. Best solution is to remove all 90wt oil & run with 105. It will not seep into the wrong side of the shift piston rod + leave it in gear compressing the shift rod compressed in reverse gear. Once I took it apart & drained out the 90wt inside the prop bore & replaced with grease it functioned much better but not good for the needle bearings I fear. I’m sure when new it shifted easy & didn’t pass lube past the shift rod. Needs grooves cut to accept a hydraulic square o-ring to seal it. I have had problems with o-rings rolling in the bore & pumping the other dead end full or leaking with surgery tables. Just go to a hydraulic shop before buying the size you need.
Anyone have a better idea? I’m listening. The gears & shafts are plenty strong as they look like quicksilver gears with straight cut teeth.

[Author]

Posts