B&S 7.0hp vs 6.5hp

Discussion in 'Mechanic and Repair' started by DLausche, Dec 10, 2006.

  1. DLausche

    DLausche LawnSite Member
    Messages: 5

    Just found this site and hoping it is ok for homeowners to post questions here as well.

    My questions are about small B&S lawnmower engines. I have a Snapper walk-behind mower with a 7.0hp B&S engine. My Wife hit a stump with it this fall and mangled the blade and bent the shaft. I had used it about 5 times total and now I need a new crankshaft :angry: Crankshafts are of course available and not too expensive but I do have an older B&S 6.5hp that I am thinking might be a donor for a crank. I am not sure if the cranks are the same or not.

    So, here are the model #'s. From what I've been reading on B&S model/type #'s, these appear to be basically the same engines.

    7.0hp (bent crankshaft) - 128602 0151E1 060215FA
    6.5hp (doesn't run, but straight crankshaft) - 126602 0134E1 000303FA

    It appears that the same B&S owner/operator manual covers both of these engines and there is only one bore (2-11/16") & stroke (2-3/64") listed for all of the engines covered by this manual. I had assumed they would be of different bore and/or stroke and that would account for the different hp #'s.

    So, a few questions I have...
    1) Are the cranks possibly interchangeable on these 2 engines?
    2) If so, then what causes the different hp #'s? Carb and/or governor tuning maybe?
    3) If I decide to swap the crankshaft, do I need an entire gasket set, or can I get by with just a crankcase gasket? I think it might be possible to get the crank out/in by removing the flywheel, engine bottom, and connecting rod cap.

    Thanks much
  2. khouse

    khouse LawnSite Bronze Member
    Messages: 1,465

    I show them as being the same crank. you will need a base gasket and both crank seals to sneak that crank out. also a good flywheel key.
  3. Restrorob

    Restrorob LawnSite Fanatic
    Messages: 11,029

    The Decal....
  4. khouse

    khouse LawnSite Bronze Member
    Messages: 1,465

    Good one Restrorob! I can't wait to put the Hemi. sticker on my 25 Command...........
  5. Jim@MilkyWay

    Jim@MilkyWay LawnSite Senior Member
    Messages: 472

    Welcome to the site.
    You are ahead of the game already since you knew to include model/specs.
    These guys-N-gals can solve most problems thrown their way. One big issue that a lot of folks have trouble with is making a clear statement of symptoms.
  6. Jim@MilkyWay

    Jim@MilkyWay LawnSite Senior Member
    Messages: 472

    When I posted this I was getting called away to actually work; WOW what's up with that?!
    I did not get to finish the post. Specifically this part "One big issue that a lot of folks have trouble with is making a clear statement of symptoms".
    I did not want you to think this was the case with your post, but a lot of the ones I read are not as clear.
    Again, welcome.
  7. DLausche

    DLausche LawnSite Member
    Messages: 5

    Wow, this site is great. Thanks guys for the responses!

    Well, I learned something last night after I posted my questions here. I started working on both engines a bit and found that the newer engine on the Snapper mower (with bent crank) has a larger diameter shaft. It looks like it is about 1" (or 25mm) vs the old engine I have with a 7/8" shaft. I should have checked this before posting, but I asked for help here, received it and now I have to come clean and admit my shortcoming. I guess it looks like I will be looking for a new engine to replace this one. It looks like I can get a new Intek OHV engine for < $200 including shipping so I think that will be the best and easiest route to getting the mower running again. I also learned last night that for the Snapper application I need to make sure I get an engine with 2 keyways on the shaft.
    That's a good one. Maybe I will look for a 6.0 or 6.5, save a few $, and then try to obtain the correct label so I can get the full 7 hp out of it. :D Not trying to be a disbeliever, but is that really true, that a 6.0 and a 7.0 are basically the same? I know that the first 2 numbers of the engine # are the displacement (i.e. 12 c.i.) and if the carb or governor is not different, then how do they get away with marketing them with different hp? Where are the small engine police when we need them? :rolleyes:

    Last question: Is there a way to Wife-proof the mower once I do get it running again?

  8. pugs

    pugs LawnSite Gold Member
    Messages: 3,025

    Actually briggs has new labelling starting now or early next year or whenever. No more HP on them. They will rate them by model series, displacement and torque.

    As for the HP goes...they can rate them at different RPM to obtain different HP numbers for what is basically the same engine.

    For example: That 2 cycle engine briggs builds for Toro...the R-tek is basically available in 3 HP ratings. 2 of them are the exact same engine rated at different RPM. The 3rd one actually has some different parts ;)
  9. khouse

    khouse LawnSite Bronze Member
    Messages: 1,465

    I don't know why I showed the same part number for the crank. Can you use
    the blade adapter off of the good crank? just because the output shaft is a different size doesn't always mean that the main journal is too. Check it out a little closer.
  10. Restrorob

    Restrorob LawnSite Fanatic
    Messages: 11,029

    Well Deon, After doing some checking on this application pugs is right.
    The 128602 high speed RPM is 3400 and the 126602 setting is 3000 that could make the hp difference, The carbs. are the same so they don't apply. Decals have been known to make there way onto the *cough cough* engine.

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