Heymow - Lawnmower Racing Forum
Engine Help => Briggs Flathead => Topic started by: Hoonigan on December 28, 2019, 09:01:30 am
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So where Im at we have a new class starting in 2020 with is for Fully built Model 28ci Flat heads!! Obviously I need a Flywheel and Starter.... But what next?!?? Any and all info appreciated!
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The sky is the limit! How far and how much you have to spend is the question.
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Camshaft and a good port job. Get the crankshaft balanced, arc rod. Try to find an 11hp head. Need a worked over carb also.
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I’d stay away from the 11hp(25ci) unless you’re able to re-work it and make it flow as much or as good as the 12hp (28ci)head , but once you think you have enough flow, get more, flatheads don’t need the compression that OHV’s do to make power the need the flow to get the fuel mixture into the cylinder, do some searching on here there’s lots of info on flatheads!
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I’d stay away from the 11hp(25ci) unless you’re able to re-work it and make it flow as much or as good as the 12hp (28ci)head , but once you think you have enough flow, get more, flatheads don’t need the compression that OHV’s do to make power the need the flow to get the fuel mixture into the cylinder, do some searching on here there’s lots of info on flatheads!
I’ll correct myself , get as much flow as possible without opening/hogging out the ports, or you’ll ruin your velocity, there’s a fine line, I’m sure other will know more, and chime in, there is a balance, sometimes less is more 😉
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Word of advice, start with a motor that has the nut on holding the flywheel on that way is is more likely to have the removable eccentrics, to allow brass counterweights, or you’ll have to get a machine shop remove the eccentrics from other cracks, saves some work
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Cost is no Issues, Id like to build it the best way I can, I have no experience building motors always ran stock but know alot of ppl and know I can accomplish what ever is needed, more so looking for someone who may be running a built flathead that could share some infor or tips as well!
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Cost is no Issues, Id like to build it the best way I can, I have no experience building motors always ran stock but know alot of ppl and know I can accomplish what ever is needed, more so looking for someone who may be running a built flathead that could share some infor or tips as well!
Pm me ,i have all the parts you need to build one,and can help you thru the process correctly
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What about valve guides? Is it best to replace them when rebuilding a 28 flathead for racing?
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What about valve guides? Is it best to replace them when rebuilding a 28 flathead for racing?
Certainly not going to hurt to ensure a proper sealing valve , along with measuring the valves for wear