Topic: flathead valves

[daddyracing]

Alright guys I'm trying to get stuff together so I can build my 12hp Briggs and I am trying to decide on valves. How big should I go? What works best? Any info is helpful

[BIG AL 202]

STOCK SIZE

[daddyracing]

So all I need is billet internals and flywheel and I will be good??

[crazycraftsman]

Figure your budget, then phone or check out EC and order what you can buy. Flywheel, billet rod,billet crank,cam,billet lifters,duel springs, billet retainers, ec carb,filter and adapter,etc ect etc. All depends on $$$
Owen

[daddyracing]

Alright thanks for the help guys. And just curious have yall ever used precision cams for parts? Or just ec

[crazycraftsman]

Yes, Mike at Precision Cams and Carol at EC are both great people to deal with. The only two places i,ve dealt with and haven't had any problems. 
Owen

[Huffy044]

My 8 hp intake was 1" from factory, I used a 1 1/2" in place of it, built a cutter to releive the head the valve was so big. Worked pretty good for me, use stock size on exhaust. I also went from 5/16" stems down to 1/4", better flow, less weight,=smaller springs, less hp to move valves.

[Mowerpar]

putting a 1.5 intake valve isn't just a drop in though.  It takes a fair amount of work, but I think it's worth it.

[BIG AL 202]

BUT IS IT REALLY WORTH THE MONEY? STOCK VALVES MODIFIED [REDUCE STEM SIZE] ARE GOOD FOR ALL BUT A NATIONAL POINTS CHASE RACER. YOU REALLY NEED TO DO ALOT MORE TO MAKE BIG VALVES WORK THAN JUST PUTTING THEM IN. YOU CAN'T JUST PUT THEM IN. YOU WILL NEED TO REDO SEATS AND GUIDES AND TO BE HONEST MONEY FOR THAT CAN BE BETTER SPENT ELSEWHERE. TO ADD TO THE BIGGER VALVES IF YOU DO INSTALL THEM YOU MUST UNSHROUD THEM TO GET THE MOST. IF YOU DON'T YOU WILL LOSE FLOW AND IN TURN WILL LOSE POWER.
  USE YOUR ENERGY AND MONEY TO MAKE IT RELIABLE AND HANDLE REAL GOOD! A RELIABLE AND GOOD HANDLING RACER IS A WHOLE LOT MORE FUN THAN ONE YOU WILL FIGHT WITH ALL DAY ON RACE DAY!

[GRUBDIGGER]

BUT IS IT REALLY WORTH THE MONEY? STOCK VALVES MODIFIED [REDUCE STEM SIZE] ARE GOOD FOR ALL BUT A NATIONAL POINTS CHASE RACER. YOU REALLY NEED TO DO ALOT MORE TO MAKE BIG VALVES WORK THAN JUST PUTTING THEM IN. YOU CAN'T JUST PUT THEM IN. YOU WILL NEED TO REDO SEATS AND GUIDES AND TO BE HONEST MONEY FOR THAT CAN BE BETTER SPENT ELSEWHERE. TO ADD TO THE BIGGER VALVES IF YOU DO INSTALL THEM YOU MUST UNSHROUD THEM TO GET THE MOST. IF YOU DON'T YOU WILL LOSE FLOW AND IN TURN WILL LOSE POWER.
  USE YOUR ENERGY AND MONEY TO MAKE IT RELIABLE AND HANDLE REAL GOOD! A RELIABLE AND GOOD HANDLING RACER IS A WHOLE LOT MORE FUN THAN ONE YOU WILL FIGHT WITH ALL DAY ON RACE DAY!

[trbinrat]

Unless you run a Kawi. They already come with the 1 1/2 valve

[GRUBDIGGER]

Unless you run a Kawi. They already come with the 1 1/2 valve

YEP!

[PJG56]

Just remember a small efficent valve is better than a large inefficent valve!   

[Jeff McKelroy]

Just remember a small efficent valve is better than a large inefficent valve!   

It's the port that's inefficient, which requires a larger valve to overcome it.  With some thought put into port flow, you just might do well with the stock size valve, and run a little more valve lift.

[BIG AL 202]