Author Topic: Porting questions  (Read 36329 times)

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Offline kohler guy

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Re: Porting questions
« Reply #45 on: May 30, 2008, 09:17:22 pm »
Flatheadpuller,
No it is not on the govenor. I am having the carb bored and the had shaved and the block "trued" up along with a three angle valve job.
So about the porting question should I take out the taper?

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Kohler Guy
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Wheelhorseracer

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Re: Porting questions
« Reply #46 on: May 30, 2008, 10:21:33 pm »
I did on my k181 Kohler... I smoothed anything that was rough... I didn't play with the short side, as these engines don't have much..

I also did what you did...but I zero decked the block, three angle valve job, 0.010 cut on the crank, 0.010 bore and new over size rod ...









These pictures were taken well before the machine work was done...

Offline kohler guy

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Re: Porting questions
« Reply #47 on: May 31, 2008, 08:25:30 pm »
I did on my k181 Kohler... I smoothed anything that was rough... I didn't play with the short side, as these engines don't have much..

I also did what you did...but I zero decked the block, three angle valve job, 0.010 cut on the crank, 0.010 bore and new over size rod ...









These pictures were taken well before the machine work was done...

Cool.... Good to know I was on thr right direction!

Thanks,
Kohler Guy
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Offline outlawmower

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Re: Porting questions
« Reply #48 on: June 01, 2008, 05:12:10 pm »
Flatheadpuller,
No it is not on the govenor. I am having the carb bored and the had shaved and the block "trued" up along with a three angle valve job.
So about the porting question should I take out the taper?

Thanks,
Kohler Guy

Yeah Take out the taper even though it is just for heavy load/ hauling stuff...

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Offline Big daddy

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Re: Porting questions
« Reply #49 on: June 02, 2008, 07:20:44 am »
 If you are going to be using stock valves then the first thing you need to do is match port the intake to the carb. unless you are going to make an intake manifold for it. If you do that then it becomes a different animal. The other thing is to remove more material on the short side radius, but don't get greedy in this area, too large a bowl area with stock valves will make the air stream do funky things. If you are wanting the strongest rod Kohler made then use one out of a K361 18 hp. single it will be stamped "ALCOA" and be fairly shiny on the top end of the rod, "IF" you can find one from Kohler, not Stenz or some other aftermarket peddler. The bearing is a Federal Mogul 9885 CP std. 0.010", 0.020" u.s. Removing the flashing might help a little, but if you are going to be turning this motor very hard then you will also need to shorten the dipper on the rod or it will break off. If you are wanting to spend the money on an aftermarket rod then I would recommend one of Chuck Vogel's.
Bruce Litton

Offline kohler guy

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Re: Porting questions
« Reply #50 on: June 02, 2008, 08:20:58 am »
Bigdaddy,
Thanks for the info....
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Offline Tuffy

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Re: Porting questions
« Reply #51 on: September 01, 2008, 11:26:23 pm »
Hi, I  run a K341 in a class almost like you are, stock stroke, .060 over max, 1.2" venturi carb, can be a recast. flat head, no aftermarket blocks. From what I have seen the bottom port in your first post is on the right track but the turn by the guide needs to be filled in so its not such a sharp turn. In my opinion a 2.1 intake is overkill but I am not a expert on what others are running.

I am running a 1.84 intake and a 1.65 exhaust. I did my intake the best I could without any epoxy or welding, it runs OK but I am down on power to the top guys in my class. I am going to a 1.94 intake this winter and  building up the port to do some reshaping. Also you want to get a GOOD steel crank, in our club we have had more than of our share of stock stroke steel cranks snapping off right behind the flywheel, seems to be much more common for the stock strokes to snap the crank than the big motors, I think it has to do with the small motors run a heavier flywheel than the big motors. The flywheel on mine is about 25lbs with the ring gear on it. I was told that if starting with a stock block to get the offset guides and move the valves closer to the piston, I didn't do this on mine so I am sort of stuck with the valves in the stock location unless I can find another block and start over. I also do all my own work because I can't afford to have others do it.

One engine I run against they basically cut the intake port off under the deck and some how welded/epoxied on a whole new lower port and the carb mounts much lower than stock. I was told it is basically the same port they run on 50 cube pro stock engines with aftermarket blocks. The engine is pretty peaky though and has to wound up big time.

Offline Big daddy

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Re: Porting questions
« Reply #52 on: September 02, 2008, 06:35:48 am »
I would'nt go quite that big with your valve, I would go with a 1.880" intake and stay with the exhaust size you have. The offset valve guide trick will still require welding up on the backside of both ports just under the deck to the valve guide plane. As far as filling up the area around the valve guide, unless you are trying to increase your torque at idle you will not see a big increase. Remember this, on a K series Kohler, most of the flow that counts is from the centerline of the flange bolt holes and up, I too have seen the epoxied motors and they do run well, but when you remove that much mass from the block then your block is not as rigid, the deck thickness on the K series varies greatly across the entire surface, and if the valve seats cannot be supported properly then you will just have heartache after heartache. If yu want to reshape the port then I highly recommend either cast welding or braze welding on top of the flange clear to the deck, build it up to the same heaght as the deck from the flange back through the center section of the port. This will allow you to reshape it correctly while remaining strong enough to hold the carb. and intake manifold. The crank issue is simple, Kohler cranks are made of cast iron, they will hold up about 35 hp/ 30 -35ft. lbs, much more than that and it will snap! I built one for a guy several years back that snapped between the counterweight and the cam gear on the inside, this happened while I was tuning the carb. face to face with it. If you do decide to start over, then stay with the K series motor and do not mess with the magnum blocks (M16). I would stay with the valves you have, get the newer piston from Vogel manufacturing, you will have to change rod length though. Keep your cam lift around 0.533" stay with the flywheel you have, don't use the offset guides, if you are going to move the valves, offset bore the guides to a bigger guide, and use a guide liner. Then it is not such a pain to have the guides changed when they go bad, but you will have to cast weld the back side of both ports if you move the valves very much. You started on the right path, just stay the path and you will do fine!!
Bruce Litton

Offline Tuffy

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Re: Porting questions
« Reply #53 on: September 02, 2008, 09:38:56 am »
Hi, Thanks for the input on mine. I should have said STEEL cranks are breaking in our club, from what I am hearing its the older Midwest cranks that have the most problems. I got a new Midwest 3.250" crank for mine when I built it, a friend had a older Midwest crank so we compared them side by side, the crank I got is much beefier than his old style one.

I am running Midwest's .025 over stock altered {JE} piston in mine, The one with the lower pin and a 5.937" rod. I have the aluminum intake support on my engine also because the port in mine is pretty thin by the time I got done with it. The port is round yet where the carb bolts on and matches the 1.5 bore of the recast carb I have, the port is about 1.4" or maybe a little less in the turn and up to where it blended into the seat. The head I have on mine is pretty old and out of date, I think a new head would help mine allot by itself.

On some tracks I can run with the better tractors in my class but on a longer nice sticky clay track I am short on power. I run a 23 gear and Lawntec tires most of the time. I do have one 1st and one 3rd this summer.


 The guy who built the engine with the intake port replaced is the same guy who built the pro-stock/super stock engines that won the engine builders cup in NQS last season, I have known him for years from local pulls years back, he still pulls with us sometimes to try out new ideas. He is the one who said to go to the 1.94 intake. I have a 11/32 valve guides in mine so I run shortened small block Chevy intake valves.

Offline Big daddy

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Re: Porting questions
« Reply #54 on: September 02, 2008, 12:37:46 pm »
The one who won the engine builders cup was MVP engines (Julian Stahl), nothing against Julian and his parts, but we only use Vogels internals. There was a rash of his cranks breaking some years back. I think he got it lined out though, I have seen some of Chuck's cranks break also, but these were really old cranks.The guy I normally run with has one of the strongest stock stroke 0.060" motors in the nation, there are some things that work in the 50 ci' engines that do not work well in the stock stroke engines, you do not need a 1.94" valve. I used a 1.950" intake with the 47 ci. engine I built and it worked well for that size engine, would have been a little overkill in the stock stroke engine. If you go back to 5/16" stem Manley valves this will help your valve weight and also make it easier to get valves for your engine with the correct geometry.That port support is just something else that may put several things in a bind once all the bolts are tightened up. The last Kohler motor I built ran with the 50 ci. aftermarket blocks, I build up the top of the port so I could reshape the port, and hung a 9" two piece manifold with a 44mm mikuni carb on it and never broke it. I know of some guys that did not weld theirs up and were ported in a similar fashion did break. Proper planning on the front end will save you money in the long run. Remember when you make your vavles bigger in a stock stroke motor you will decompress it somewhat, same goes for really high lift cams in that same size engine.
Chuck's new pistons will save you some weight over the J&E pistons and with the new coating will help keep the engine heat in the combustion chamber where it belongs.
Bruce Litton

Offline Tuffy

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Re: Porting questions
« Reply #55 on: September 02, 2008, 11:48:22 pm »
Sounds like you know much more than I do about this stuff. I have run the later Midwest crank for 2 years now without a problem. I wish I had my own dyno to play with, I think my learning curve would speed up a whole bunch. We had my engine on anothers guy dyno 2 years ago, but I have changed alot in the engine since then. I do have a Vogel cam in mine by the way.

Offline Big daddy

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Re: Porting questions
« Reply #56 on: September 03, 2008, 09:44:46 am »
You and me both on the dyno situation. I keep playing my $5 on lottery each week so that someday I might be able to buy one, There are some people with good dynos that will rent them out by the hour, $50-100/hour sounds like a chunk, but if you price driving time and fuel to each pull to test stuff out you will definately come out money ahead on renting dyno time!!
   Just curious, how much mallory metal did it take to get your MSC crank balanced? I like the shape of the MSC counterweights, but I believe the counterweights are too small. A friend of mine used a 3.875 crank some years back and I think it took one more slug per counterweight than the Vogel crank.
Bruce Litton

Offline Tuffy

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Re: Porting questions
« Reply #57 on: September 03, 2008, 10:10:25 am »
I didn't have to do anything to the crank, when I got it Julian wanted to know which rod and piston I was using and he said he had the right weights for that setup because it is so common. I ran the crank the way it came out of the box. My stock class OHV Tecumseh vibrates worse at 3800 rpm than my Kohler does. The guy with the dyno was impressed also how smooth it was for not having it balanced. When we compared my crank to the older version that was one of the big differences, the weights on mine were huge compared to the older crank. in fact I was worried because the Vogel rod I had at first just barely cleared the inside of the weights, I think there was about .027" clearance between the rod and the weight on each side, but they never touched each other.

I got lucky on the dyno thing, he was a friend of a friend of mine who built my friends .060 over engine, we spent most of a day with mine on the dyno and made 12 pulls and it cost me a little over $100 for the whole day. I was about 5 or 6 hp down from his engines back then but I think I am closer now but still hurting on a good long power track.

 

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