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Head's Shaved

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Author Topic: Head's Shaved  (Read 1349 times)
Whiplash_Syndicate
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« on: June 28, 2007, 10:05:06 pm »

Does anyone know how much I can shave the heads on my 19hp briggs 42 ci. I decided to try to build it but dont want to mod heavly YET.Any info would be greatly appericated.Thanks
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rebelracing16
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« Reply #1 on: June 28, 2007, 10:19:36 pm »

What size cam will you be running?
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Larry n Jeannie Favors
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Whiplash_Syndicate
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« Reply #2 on: June 28, 2007, 10:42:24 pm »

Stock for now.
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rebelracing16
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« Reply #3 on: June 29, 2007, 06:34:18 am »

You can go as much as 70 thousndth with a big cam. Stock cam maybe not so much, maybe 30. Help us out George.
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« Reply #4 on: June 29, 2007, 07:50:51 am »

I never built an apposed twin, I would say .035 with no cam.
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George Herrin #6
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« Reply #5 on: June 29, 2007, 07:58:43 am »

Just two flatheads working against each other.
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« Reply #6 on: June 29, 2007, 03:59:46 pm »

But I don't shave my flat heads..... If I were to though no more than .035
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George Herrin #6
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Life should not be a journey to the grave with the intention of arriving safely in a pretty and well preserved body, but rather to skid in broadside, thoroughly used up, totally worn out, and loudly
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« Reply #7 on: June 29, 2007, 06:03:04 pm »

Ya! flat heads are close to values any way. Not much need for more compression.
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Larry n Jeannie Favors
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Whiplash_Syndicate
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« Reply #8 on: June 29, 2007, 06:07:18 pm »

I was thinkin along the lines of 0.030 or so.Thanks guys I will have the motor back from the machine shop in a month.(He is the best around so he is real busy) and I will have it assembled soon after.Hope to have all complete by the end of this season and pratice some for next season.
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flafx274
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« Reply #9 on: June 29, 2007, 10:16:09 pm »

From what I have been told, shaving the head to boost compression on a flatty is not nearly as important as getting the port work right to increase airflow. By getting more air/fuel in you have more to compress therby raising the compression pressure. Hope this makes sense.
Tom Ast
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Tom, Florida
Whiplash_Syndicate
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« Reply #10 on: July 01, 2007, 12:23:09 pm »

Yea I'm Having it port and polished also.I want to do all I can Machine work wise now and wait a while till parts get a little cheaper for the opposed and then do some building.
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« Reply #11 on: July 18, 2007, 08:10:24 pm »

Tom you were told rite,flatheads don't need or like high compression.They like and need fuel and air flow,these will make more power than compression.High compression will restrict both.Only deck the head and block enough to square them up.Another thing is pop up they don't like that either try to keep it .005 or less.A good port job and good flowing carb.will wake one up.
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« Reply #12 on: July 23, 2007, 09:53:08 pm »

Unless your planning on running racing fuel, don't shave the heads. High compession needs high octane or you get preignition or pinging and if that happens, well you might as well take your ballpeen and knock a hole in the pistons, cause that's what you'll end up with. It's all about the flow, aka volumetric efficiency.
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Scott Nelson
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