5 hp mods

[sayre315]

well if your gonna mod a 5hp what i would sudgest is the following:

high lift cam
billet rod (or a horstman rod)
high compression head
heavier springs
header
govener removal
billet flywheel (optinal)
shaved eyebrows
stainless steel valves
ported, umm ports
and if you want you could throw in a tillotson

to me, doing this to an engine is sorta fun, kinda like restoring a car
but if this list seams too long and expinsive and all you want is more speed than i say you should just:

shave the eyebrows
remove govener
add a 15" or so piece of 3/4" pipe
and port and lapp the valves

 

[jr dragster T]

No need for SS valve's in that kind of motor. A big cam is not alway's a good thing. And if your not good at porting you can actually make the flow worse. And Russ howcome the fuel nipple is on the side of the tank then? Must be a little tube going to the bottom.

 

[Kenny_McCormic]

Isn't one of the mods people do, sticking a 3HP Briggs flywheel on a 5HP?

Good way to die.

 

[jr dragster T]

^I agree. Why wont people spend $100 on a flywheel instead of buying trash like REALY stiff valve springs and a new cam. It's just ASKING for trouble. IMO If I only had like $200 to spend on a motor I'd make a healty box stock motor. Like a flywheel and a header, Filter and a few more little goodies.

 

[kibble]

I'm asking some questions only cuz I have no experience in doing this. So, what about the coil from a 3? Is it better than the one in a 5? I've just seen some stuff about it and I would like to mod one of those 5's just for the heck of it. I know where I can get a 3hp briggs, but I have yet to find a 5.

 

[newrider3]

Nothing wrong with a cast iron 3hp, as long as you stick to the same RPM as a 5. The cast aluminum mower units are what you should worry about.
Stock Briggs flywheels don't just explode if you look at them sideways. They start to explode once you reach Limited or Modified engine caliber and the associated RPM. Stock class racers are required to run a stock 5hp flywheel, and they run 6000-7000 all night long. They will explode, but there is a threshold that has to be broken first. Unless you take pleasure in hammering off, dropping, or using an impact on your flywheel.

 

[oscaryu1]

Good way to die.

?

How? 3HP flywheels have been spun by racers 8500+, they're a simple mod to PREVENT explosions. Less rotating mass, there are plenty of CAST IRON 3HP flywheels that will spin high fine... (though I don't recommend it), it's the ALUMINUM flywheels you want to be watching out for.

And yes it's possible, but you need to get a coil bracked, and modify it if it's not a ARC coil bracket (I've needed to do so)

 

[newrider3]

You don't need to mod the bracket if you get the matching 3hp coil.

 

[jr dragster T]

All this BS I hear is from internet story's Go spin a stock cast iron flywheel at 8500 RPM. I can gurantee you that you may have some probelems!

 

[Kenny_McCormic]

?

How? 3HP flywheels have been spun by racers 8500+, they're a simple mod to PREVENT explosions. Less rotating mass, there are plenty of CAST IRON 3HP flywheels that will spin high fine... (though I don't recommend it), it's the ALUMINUM flywheels you want to be watching out for.

And yes it's possible, but you need to get a coil bracked, and modify it if it's not a ARC coil bracket (I've needed to do so)

I would rather go billet PEACE OF MIND.

 

[oscaryu1]

You don't need to mod the bracket if you get the matching 3hp coil.

Well most auctions and places I see sells the bracket by itself.

All this BS I hear is from internet story's Go spin a stock cast iron flywheel at 8500 RPM. I can gurantee you that you may have some probelems!

Plenty of people who do so. The Clones brought back the OMG's of flywheel explosions.

I would rather go billet PEACE OF MIND.

Got $150?

 

[jr dragster T]

Well I know for sure if you dont have $150 I wouldnt do it. If you had to pay $150 to live would you? Of course you would so dont screw around with cast iron!

 

[Kenny_McCormic]

Costs more than $150 to have the hospital remove cast iron from my back...

 

[newrider3]

Let me know when you build a FUN KART engine that can spin up to the speed it takes to blow a flywheel, without blowing anything else first.

Last time I checked, the only racer here is Mr Tyler. I wouldn't touch a cast iron flywheel to his drag engine with a 10 foot stick. But he is spinning >10,000 RPM from the get go, and I see it unlikely you are doing the same in your back yard or down the street.

 

[oscaryu1]

Let me know when you build a FUN KART engine that can spin up to the speed it takes to blow a flywheel, without blowing anything else first.

Last time I checked, the only racer here is Mr Tyler. I wouldn't touch a cast iron flywheel to his drag engine with a 10 foot stick. But he is spinning >10,000 RPM from the get go, and I see it unlikely you are doing the same in your back yard or down the street.

Doesn't his clutch engage at about 5k?

 

[sayre315]

idk oscar but i remember him telling us it idles at 3k
Mr. Russ told me a few weeks ago that a briggs 5hp engine will only spin 4500 with no govener and a straight pipe and it wont increase unless you add a bigger cam

 

[Russ2251]

idk oscar but i remember him telling us it idles at 3k
Mr. Russ told me a few weeks ago that a briggs 5hp engine will only spin 4500 with no govener and a straight pipe and it wont increase unless you add a bigger cam

I said that?
Please show me!!!

 

[Kenny_McCormic]

They will only spin 4500 because the valve springs arent heavy enough. The rod breaks in the 4000s

 

[oscaryu1]

They will only spin 4500 because the valve springs arent heavy enough. The rod breaks in the 4000s

? I've heard 5000's, but I ain't sacraficing a 5HP block and rod to find out

I have spun a Briggs 2/3HP 4000+ though. No load, bad idea, but I was only 11 lol.

 

[Scorch3]

I have 6.5 hp clone and if i have this right all i would need to do is change the fly wheel and remove the governor to get what an extra 1000 rpm. By the way when the say 6.5hp at 3600 rpm i can assume the governor keeps it form going over 3600rpm? And out of curiosity where abouts would this idle and when would i want my clutch to engage.

Sorry for all the questions but i am a newb after all.