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trowel

reboring 300421 12 hp into 14 hp engine ?

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OkieGT

Besides asking someone I would look at both engine specs to see if it list wall thickness or how big you can bore one. Lets say a 12hp is 3.25 bore and a 14hp is a 3.50 bore, that would be .25 difference. I think when we talk about overborring though were only talking about .010, .020, .030, and maybe .040. Do I have this right?

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trowel
spyder400k

ok in my engines ive redone its in the cam the 16 hp cam is differant than the 12 its in the cam lift thats how the engines timing is done. how long the valve is open this is the differance in hp thats how briggs did the engine sizing the best is a 12 rebore to a 16 stock and use a stock 12 cam much better smoother running engine in my experiance. a 12 rebore with a 16 cam much more vibrations with the higher lift cam. as far as valves all 12 to 16 are the same int and exh. as far as cly heads in 12 all the same in 14 to 16 2 differant heads that ive came across so far hope this helps out.

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RayS

The cams in a 12hp and a 16hp both have the same part numbers. So do the tappets.

The 12hp cams old part number is 211794 and the new number has been changed to 692855.

Tappet numbers are changed to 691594 from 26670 in the 12hp.

They should be the same if the numbers are the same.

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trowel

Thanks, i was thinking of the valves, ran the numbers last night and it matched the 12 hp engine.

Ray, your right, i spent a few hours last night running internal part numbers.

It seems if i retain the original head and bore to 32 cub. in. it makes a 15 hp, with that said, wonder if i mill .005 off the head it would make a 15 1/2 hp or therabouts.

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trowel
quote:Originally posted by spyder400k

yes the tappets are the same but the came lift is differant on the cam lob the 12 is a smaller lift than a 16 the 12 is 1.207 and a 16 is 1.235


id="quote">
id="quote">That make sense, with the piston sucking more air and gas it makes sense it would vib more then the short stroke valves.I'll bet your converted engine revs up fast with the short stroke valves:DJust getting it out there, im not interested in building a hopped up pulling engine, just saving and reusing a 12 hp block to build a worker, i have a bead on a sickle mower and live on a farm, lots of acreage that is overgrowning, lots of yards and long driveways and none of it is on flat land.

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RayS

The 12hp manual states the exhaust valve as part number 261207 which supercedes to part number 394436. The intake was 261206 and is now 394435.

In the old 16hp part manual the exhaust valve was part number 261207 and changed to 261584 before date code 8011130 and changed again to 394436. The old number for the intake valve was 261206 and was changed 261583 at the date code above and then changed to part number 394435.

They both supercede to the same numbers as well. Not sure why they changed the numbers. Could be number updates or types or changes to gas that needed different types of metal used in the valves.

From checking these numbers over the years. The differences I see are bore diameter, cylinder heads and maybe different carb numbers. The rest seem to supercede to the same numbers for the parts. Except the piston of course.

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trowel

This is why i love the old cast iron Briggs so much, for a lot of the walk behind tractors i have interchanged parts between the N, 5, 6 and 8. The 13000 series, 14000 series, vertical shaft, horizontal shaft etc...

On the newer alloy Briggs, very few.

Can't do that with a Winnie pooh engine either.

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trowel

The gov on the 12 hp is no good, looked at the numbers for the 23D parts block and number is different, has anyone interchanged the gov between the 23 cub inch with the 32 cub inch engine ?

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OkieGT

be careful using the abbreviation "cub" for cubic "cu.", it might get a off color comment, lol

quote:Originally posted by trowel

Oh, never mind, my bad, missed the superseded numbers, double checked and it came back the same as the 32 cub engine.


id="quote">
id="quote">

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huffy

Here's another thread that might be of interest to you, Trowel.

The thread above has all the info about parts, etc, needed for the rebuild, but this one has more pics of the tear down and rebuild that I did on one of the motors.

http://www.simpletractors.com/club2/topic.asp?ARCHIVE=true&TOPIC_ID=121043&whichpage=2&SearchTerms=2012

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trowel

Wow, many thanks for taking the time to find all this.

Thinking of shoving this into the round hood Allis.

Just throwing this out there, after i finish stripping the 23D block, if anyone in Ma is looking for a base block with the original piston and rod to rebore and rebuild let me know.

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huffy

Trowel:

They weren't hard to find; they were my posts.

Both the ones I did went into the 2 round hoods pictured. You should know, though, that that's quite a bit of power for these little fdt's. If you're not careful to throttle down before releasing the clutch, and don't have any weight on the front, it'll pop the front wheels off the ground easy. Mine will, in fact, back flip over on top of me if I'm not careful. It's more motor than the tractor needs, frankly.

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trowel

Thanks anyways, still bumbling around this fourm,

Yes, they are, lol, took off the snow thrower but still had the rear weight box, studded tire chains, stinger and doughnut, foot slipped off the clutch/brake pedal and she popped a wheelie on the hill, lol, my heart skipped a beat and that was just with the 9 hp Squire at half speed.

The Sears SS12 was very good power, with the high/low range it was great as a worker.

With the Allis i plan on welding something slip resistant onto the petal.

Im a farm boy use to the old farm tractors from the 50's and 60's if you know what i mean.

I plan on weighted ag tires and front weights to make for a solid work platform for sickle mowing, wood chipping, grading/ditching and snow throwing, the 12 hp needs a rebuild anyways.

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skunkhome
quote:Originally posted by OkieGT

be careful using the abbreviation "cub" for cubic "cu.", it might get a off color comment, lol


id="quote">
id="quote">My exact thought. I had to check to see if I were on the wrong forum. :DHad me making a double take.

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