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Inquiring on racing parts for 12 HP briggs

#1

M

MowerJo19

62868BD4-8A6F-4B14-B8C6-1A5723D563AC.jpegI have a 12 horsepower Briggs and what I believe to be a flat head I was wondering what the model of these engines generally are or how to find the specific model number, because Im trying to upgrade it with aluminum billet flywheel and billet connecting rods etc. Im new so I may not have the best terminology.


#2

M

MParr

Try these folks.

ARC Racing Brands

www.arcracing.com www.arcracing.com


#3

S

slomo

Trying to beat your neighbor in yard cutting? How fast do you want to get back on the couch?


#4

StarTech

StarTech

If he just wanting more top end torque all he got to do is change the camshaft timing by one tooth. I just don't remember which i did it back in he 80's.

Otherwise if the OP got more money than he wants he could always send some my way.


#5

Mower King

Mower King

StarTech said:
If he just wanting more top end torque all he got to do is change the camshaft timing by one tooth. I just don't remember which i did it back in he 80's.

Otherwise if the OP got more money than he wants he could always send some my way.
Click to expand...
You moved the cam, 1 tooth on the crank gear......you actually did this?


#6

StarTech

StarTech

mower king said:
You moved the cam, 1 tooth on the crank gear......you actually did this?
Click to expand...
Yelp I did back then on my personal Ford rider but as I said don't remember if I advance or delayed the timing. I had other things at the time to worry more about in the 80's. I just know I had more torque cutting grass.


#7

M

MowerJo19

StarTech said:
Yelp I did back then on my personal Ford rider but as I said don't remember if I advance or delayed the timing. I had other things at the time to worry more about in the 80's. I just know I had more torque cutting grass.
Click to expand...
Maybe low end torque I’m not sure if I wanna do tractor pulls or not.


#8

M

MowerJo19

MowerJo19 said:
Not sure what I wanna do yet I wanna do tractor pulls but race sometimes.
Click to expand...


#9

Mower King

Mower King

StarTech said:
Yelp I did back then on my personal Ford rider but as I said don't remember if I advance or delayed the timing. I had other things at the time to worry more about in the 80's. I just know I had more torque cutting grass.
Click to expand...
The reason I asked that is, 1 tooth either way, advanced or retarded, is too many degrees to run real good or better than O.E.M. setting.....now a few thousands, yes...but 1 tooth, nope!
The attached pic is how I do it!

Attachments





#10

B

bertsmobile1

For some cams there are vernier adjustable timing, usually about 1/4 degree per pin slot
For pulls you want a small carb and a long inlet tract
For revs you want a big carb, big short valve openings and a short manifold with a long air ram.
Then you need to extensively build up the heads so you have discreet paths for the inlet & exhaust, then grind out the combustion chamber so it is 100% over the piston.
move the spark plug so it is about 1/3 the diameter distance from the closed side of the cylinder to get most of the combustion happening over the piston.
Even then 7000 RPM is the best you can hope for which you can not do with a std piston , conrod or crank.
Serious Hp will require ball & rollers on the crankshaft & steel con rod


#11

M

MowerJo19

I can’t find the engine code anywhere on the engine, but I didn’t look on the carb or on the spark plug could it possibly be under the cover.

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#12

Mower King

Mower King

I'm not sure where they are located on the cover/shroud of a 12 HP but, there are usually 3 lines of #'s stamped on it. You have to look at every square inch of the shroud real good. I guess there could be a tag on the shroud also but, most likely stamped!


#13

M

MowerJo19

mower king said:
I'm not sure where they are located on the cover/shroud of a 12 HP but, there are usually 3 lines of #'s stamped on it. You have to look at every square inch of the shroud real good. I guess there could be a tag on the shroud also but, most likely stamped!
Click to expand...
All I could find Is Model 281707 Type 041501 Code 90032731


#14

StarTech

StarTech

That is what they are needing. 281707-0415-01 Manufactured March 27, 1990 in plant 31


#15

M

MowerJo19

StarTech said:
That is what they are needing. 281707-0415-01 Manufactured March 27, 1990 in plant 31
Click to expand...
Yeah, but I can't figure out the model is it a model 19 or 28?


#16

B

bertsmobile1

Measure the bore & stroke
Big difference between 19 Cu inches and 28 Cu inches
Within engine types most blower housings are interchangable but usually not between OHV & SV engines so you can never believe the numbers on an engine you did not buy new.


#17

StarTech

StarTech

StarTech said:
That is what they are needing. 281707-0415-01 Manufactured March 27, 1990 in plant 31
Click to expand...
The first two digits is the cu in of the engine so this one is 28 cu in.


#18

B

bertsmobile1

StarTech said:
The first two digits is the cu in of the engine so this one is 28 cu in.
Click to expand...
provided the blower housing is the one the engine left the plant with .
Been caught out by swapped housings on more than one occasions


#19

M

MowerJo19

I kinda wonder if a 34mm Mikuni from go power sports would bolt up to it...


#20

Hammermechanicman

Hammermechanicman

Hot rodding a 12hp flat head is essentially the same as the 5hp used for years in WKA racing. Installing a larger carb without a cam change is uselesss. The 5hp can run at 6000 RPM with the stock rod. The 12hp can't. As far as i know there is no AM rods or cams for the 12hp. Things that can be done to the 12hp is:
Using offset key to advance timing
Mill head and relieve for valves
Deck block for zero piston popup
Grind easy spin bump off the cam
Valve lash to .003
Remove the govenor at your own risk.
If the compression is raised by removing the easy spin bump on the cam and the head is milled the electric started probably won't be able to crank the enine iver.


#21

M

MowerJo19

I found one on Eccarburators site but its for non-avs engines whatever that means??


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