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Discussion Starter #1
Today I was assembling one of my K341 to put on my '69 140. I got the short block done and went to see what the flatness of the heard was. On a 1/2" piece of plate glass, I could get a .006" feeler gauge between two of the bolt holes around the exhaust (common place on Kohler heads). In the past, I've used the plate glass and sand paper, but with so much to remove, I thought I would try milling it on the Bridgeport. The reason I never tried one before was the setup up time, but as I looking at it and did some thickness measuring, I laid it in the vice on 2 parallels (laying flat) and mounted the flycutter.


First pass was ,010" and as you can see, that didn't quite get all of it. (upper left) It's hard to tell but I took the photo while it was still cutting.









Another .004" pass and it looks good as new. Now I know I can do them, I'll never be doing the sanding method again







Now it's off for a overnight stay in the solvent tank.
 

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Discussion Starter #4
That's a very smooth job... I hope the block is just as flat... 🤞 :ROFLMAO: 🍻
Took a machinist straight edge on gasket surface and couldn't get a .001" feeler gauge under it.:)
 

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Parts collector
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Dang nice work and it must be nice to have those kinds of tools at hand. ;)
 
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That is impressive. Nice work!


Sent from my iPad using Tapatalk
 

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Did you run a indicator over the mounting surface before the first cut? The first seems to be a lot to take off if it was only .006 but it looks great👍
 

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Discussion Starter #10
I used the fly cutter and checked to make sure that the head gasket surface was parallel to the cutter by taking a .0005" trial cut first.
The .006" feeler gauge was the only one I tried (as it was open and handy) and it fit somewhat loosely. After it was milled, I took a dial indicator and found the lift on the valves and then checked the head with a depth mic to make sure I had enough clearance. Had .011" clearance without figuring the head gasket thickness. I could of taken another .010" off and still felt comfortable with it. Just didn't want take a chance of having too much compression and have to run high octane gas or octane booster. I only use 87 octane ethanol-free gas in my tractors. After using methanol for 20+ years of kart racing, I know what it does to to carburetors if they arn't flushed with pure gas.

I worked part time for a kart/jr dragster engine builder for 5 or 6 years. All of the engines I built were kart engines, built to IKF and KART specs. All parts were stock Briggs parts but the camshafts, tappets and valve retainers. The camshafts had to stay within a few degrees of the stock profile including the EZspin (Briggs compression release). The way the aftermarket cams worked was by controlled intake valve float. The intake ramp would throw the intake open to coil bind. The block decks were cut so the piston would pop out of the cylinder about .003" (.005" was spec max). The head had 3 minimum measurement and we milled them down enough just to stay within specs. Most would be around 12hp on the dyno, but a few got over 13hp and I still have 3 of them (13hp) out in the shed, even though I haven't raced in 16 years. We ran these engine between 6,000 and 6,300 rpm and they lived for 15 races before they were refreshed.
I've seen a all out race 5hp jr dragster engine, pull 29hp on the dyno. It was scary in the dyno room when I fired that one up.
 
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I’ve seen these small motors make serious HP,Kirk engines builds pulling motors,he is a guru on Kohler motors
 
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