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Engine Help => Briggs Flathead => Topic started by: offroadwhatever8 on February 01, 2007, 10:24:20 PM

Title: Everything you ever wanted to know about modifying a 3 hp Briggs..here..
Post by: offroadwhatever8 on February 01, 2007, 10:24:20 PM
Are 3 and 5 hp carbs the same? from what i know they are, but i want to make sure before i buy a 5 hp carb kit off ebay and when it gets here its the wrong one. Thanks John
Title: Everything you ever wanted to know about modifying a 3 hp Briggs..here..
Post by: offroadwhatever8 on February 02, 2007, 06:06:13 PM
I would like to port my 3 hp briggs, i do not have a die grinder, but i do have a dremel 400 xpr. I just need to know which is the best grinding wheel for when i do it  :confused: Thanks, John
Title: Re: Best Dremel Grinding Wheel for Porting
Post by: offroadwhatever8 on February 02, 2007, 07:11:21 PM
Randy, Rocky, George Any one  :confused:
Title: Re: Best Dremel Grinding Wheel for Porting
Post by: sr71mopar on February 02, 2007, 07:26:38 PM
For mild blending on aluminum, I like to use cartridge rolls like these:
(http://i11.photobucket.com/albums/a191/sr71mopar/rolls.jpg)
Title: Re: Best Dremel Grinding Wheel for Porting
Post by: mightymowe on February 02, 2007, 07:52:38 PM
The sandpaper is probably the best unless you can find burr's that are for nonferrous metals the burr's that are for ferrous metals like to plug up in aluminum unless you use some lubricant
Title: Re: Best Dremel Grinding Wheel for Porting
Post by: offroadwhatever8 on February 03, 2007, 11:07:18 AM
Thanks  :)
Title: more questions
Post by: offroadwhatever8 on February 04, 2007, 09:27:58 PM
If i shave the head, and port my 3 hp, how much of a power gain would that be? I just dont really wont to spend a hole lot of money on billet fly wheels and such becuase i could just get a 5 hp with that amount of money, so im limited down to just shaving the head and porting.
Title: Tecumseh carb on 3 hp briggs
Post by: offroadwhatever8 on February 04, 2007, 09:46:52 PM
I dunno if this would work and if it did i don't know if it would increase power. If i made a special adapter to fit a 6 or a 8 Tecumseh carb to my 3 hp Briggs, would this work? I came up with this idea literally 2 seconds ago, so tell me if i just made a complete idiot out of my self

I also found this, just look at the adapter and carb, thats kinda what I'm thinking about... Thanks John

(http://i144.photobucket.com/albums/r162/offroadwhatever8/th_bcc80e00.jpg) (http://i144.photobucket.com/albums/r162/offroadwhatever8/bcc80e00.jpg)

NOTE: THIS IS BASED ON THE MOTOR NOT THE MINI BIKE

Title: Re: Tecumseh carb on 3 hp briggs
Post by: money89tractors on February 04, 2007, 10:14:47 PM
ive seen many adaptors to put briggs carbs on tecumseh engines, and vise versa. but the big question to me is why would you want to? tecumseh engines (stock) seem to have many problems with their carbs. if you are wishing to put a bigger carb in  your little 3 hp engine, why go to a different manufacturer?

if the 6 or 7 hp carb will work on t he 3 hp, without flooding it like i would think it would, you could just as easily to adapt a 5, 6, or 7 hp briggs carb onto it.

if you build up the 3hp with a good cam, lighter flywheel, stiffer valve springs, lighter piston, billet rod, offset flywheel key and possibly a bore over then i could see a reason to use something like a 8hp carb, maybe, due to the extremely high rpm's you could/would turn.

if you really just want to but a slightly larger carb on the 3 hp, to see if it helps with power any, get a 5hp carb, and make an adapter.

-Phil
Title: Re: Tecumseh carb on 3 hp briggs
Post by: allen minaker on February 05, 2007, 11:33:29 AM
 .

Offroad - I would think with some mods and a custom intake you should be able to run any type of carb . just make sure it's not overkill .
Title: Re: Tecumseh carb on 3 hp briggs
Post by: crocco58 on February 05, 2007, 11:39:56 AM
Have you ever checked out this place: http://4cycle.com/ ?
Title: Re: Tecumseh carb on 3 hp briggs
Post by: allen minaker on February 05, 2007, 11:52:08 AM
Cool site !!!!!!!! THANKS
Title: Re: Best Dremel Grinding Wheel for Porting
Post by: TheMowinCuban on February 05, 2007, 12:32:22 PM
i didnt even use a dremel on my carb, i just put sand paper on the end of my finger and worked away at it!
Title: Re: more questions
Post by: TheMowinCuban on February 05, 2007, 12:35:05 PM
after porting your carb, you should notice A LOT more power on top end, but to get low end power, you'll have to supercharge it kind of like i did, also grind up 1 moth ball and add it to your gas, it increases your octane in your gas, and you will get even more power, and you'll start to notice some pretty big flames comin from your exhaust!!
Title: Re: more questions
Post by: offroadwhatever8 on February 05, 2007, 12:38:23 PM
cool, thanks dude

Isnt adding moth balls bad for the engine? I herd they can give you more power but they can harm the motor. But ill have to give it a try  :)
Title: Re: Best Dremel Grinding Wheel for Porting
Post by: offroadwhatever8 on February 05, 2007, 12:45:03 PM
How long did that take?
Title: Re: Best Dremel Grinding Wheel for Porting
Post by: mike on February 05, 2007, 04:06:48 PM
are you using a 3hp on a rider  :omg:
Title: Re: Best Dremel Grinding Wheel for Porting
Post by: matt25001149 on February 05, 2007, 04:41:15 PM
i dont think he is but my dad had a front mower rear steer mower with a 5 hp on it and that thing had balls man
Title: Re: Best Dremel Grinding Wheel for Porting
Post by: offroadwhatever8 on February 05, 2007, 04:49:05 PM
lol, they do. People always under estimate those engines but they can haul  :censored:. My huffy has a 5 hp briggs in it and it will pull me around where ever i want.
Title: Re: Best Dremel Grinding Wheel for Porting
Post by: ryf on February 05, 2007, 05:01:37 PM
unless your a big boy (like me) 3-5hp has been powering go carts for as long as I remember. I think the bigger motors really help more with not bogging when mowing grass, and full out racing of course.

with some 4hp weighing in at 32lbs, 3.5hp at 26lbs with a light rider would probably be pretty fun, especially good handling if it found itself on a light well setup mower too.... learn how to weld aluminum, and make the AlumiMower!
Title: Can I do Advanced Timing on My 3 HP Briggs???
Post by: offroadwhatever8 on February 05, 2007, 05:02:58 PM
After a shaved head and porting, how much would advanced timing help? Is it even possible with such a little motor? Im new with advanced timing, so please help. Also, where is a good place to buy the fly wheel keys? Thanks John
Title: Re: Best Dremel Grinding Wheel for Porting
Post by: offroadwhatever8 on February 05, 2007, 05:16:45 PM
well, if its going on any mower is the huffy. The huffy is real light and real small.

(http://i144.photobucket.com/albums/r162/offroadwhatever8/th_Picture005.jpg) (http://i144.photobucket.com/albums/r162/offroadwhatever8/Picture005.jpg)
(http://i144.photobucket.com/albums/r162/offroadwhatever8/th_Picture007-2.jpg) (http://i144.photobucket.com/albums/r162/offroadwhatever8/Picture007-2.jpg)
(http://i144.photobucket.com/albums/r162/offroadwhatever8/th_Picture008-1.jpg) (http://i144.photobucket.com/albums/r162/offroadwhatever8/Picture008-1.jpg)
(http://i144.photobucket.com/albums/r162/offroadwhatever8/th_Picture191.jpg) (http://i144.photobucket.com/albums/r162/offroadwhatever8/Picture191.jpg)



Title: Re: Tecumseh carb on 3 hp briggs
Post by: mowdak1 on February 05, 2007, 05:34:02 PM
I would think there to be an unlimited number of options in the 5hp Briggs carb considering the availability of kart carburetors out there in the world. Might be a better option and you may well be able to find an adapter for this combination out there also.
Title: Re: Tecumseh carb on 3 hp briggs
Post by: offroadwhatever8 on February 05, 2007, 06:07:28 PM
Thanks Rocky  :)
Title: Re: Best Dremel Grinding Wheel for Porting
Post by: DanW on February 05, 2007, 08:11:31 PM
I used a $15 Forney carbide burr on a Honda D block to notch the bottom of the cylinder walls out, when porting the manifold to the exhaust gasket size, and on my turbo exhaust inlet.  That thing is a fricken beast.  Not any aluminum from the block stuck in it, and it zips through cast and steel like it's butter.
Title: Re: Best Dremel Grinding Wheel for Porting
Post by: offroadwhatever8 on February 05, 2007, 08:27:01 PM
hmmmm, i extremely anxious to port it, from what people been saying, it makes a huge difference. I cant wait to get to it this week.
Title: How Far Should I Go
Post by: offroadwhatever8 on February 05, 2007, 09:05:09 PM
When i port the 3 hp, how much should i take off? im just afraid if i go to far that the fuel may start to "puddle" in the intake. Thanks John
Title: Re: How Far Should I Go
Post by: matt25001149 on February 05, 2007, 09:22:23 PM
dont take any off just clean it up a lil on intake side leave it rough dont polish it
Title: Re: How Far Should I Go
Post by: Steven J on February 05, 2007, 09:29:14 PM
Heres an article I found worth reading about porting and polishing its about motorcycles but the concept is there and it all about the ups and downs of porting and polishing http://www.motorcycleproject.com/motorcycle/text/cows-porting.html
Title: Re: Everything you ever wanted to know about modifying a 3 hp Briggs..here..
Post by: mightymowe on February 06, 2007, 06:07:57 AM
Very good article on porting,I believe fuel puddling in the intake has more to do with port velocity,than the finish in the port,and the very best ports are the smallest ports that do the job.
Title: Re: Everything you ever wanted to know about modifying a 3 hp Briggs..here..
Post by: offroadwhatever8 on February 07, 2007, 06:19:13 PM
Quote
dont polish it
How come? what will happen?  :confused: Wont that make it flow more?
Also, Just to make shore,

When i measure the head to figure out how much needs to be taken off, I just simply put model clay on the head and turn the engine over a few times then measure it with a dial caliper? are there any easier ways? I rather not go out and buy a dial caliper. Dose any one know off the top of there head on how much i should take off? Thank's John
Title: Re: Everything you ever wanted to know about modifying a 3 hp Briggs..here..
Post by: Squidd on February 07, 2007, 06:28:56 PM
If you don't have a dial caliper...how will you know how much you started with...or how much you "took" off...???
Title: Re: Everything you ever wanted to know about modifying a 3 hp Briggs..here..
Post by: offroadwhatever8 on February 07, 2007, 07:26:07 PM
to be honest, i really dont know  :doh:
I can probably just barrow by neighbors com to think about it.....
Title: Re: Everything you ever wanted to know about modifying a 3 hp Briggs..here..
Post by: Ethanperez04 on February 21, 2019, 08:45:48 AM
Does anyone know where I can get a custom 3hp Camshaft made for my 3hp briggs and stratton.
Title: Re: Everything you ever wanted to know about modifying a 3 hp Briggs..here..
Post by: BIG AL 202 on February 21, 2019, 05:32:57 PM
Look in the links for cam grinders.