K91 Non-Threaded Exhaust Port

[RJ Hamner 992]

The good news:  Finally found a K91 for my Suburban

The not so good news:  The exhaust port is not threaded

The parts book lists a "spacer" part # 220819. I thought about getting one and get it threaded.

I thought the idea had merit but.......discontinued part.

Has anyone found a "fix" ie connector welded to a flange????????

I am open to ideas

Thanks

Bob

[ACman 7,504]

You could go the flange route or tap it with a 1/2" N.P.T . 

 

If if your not comfortable with this a good machine shop could do this and even open it up to 3/4" like the original blocks had .

 

Use the search box ... try pipe tap exhaust port .

 

Good luck  !

 

[Achto 26,454]

Some have tapped the hole to 1/2"npt then used a bell adapter to go to 3/4"npt. The restriction of the 1/2"npt threads will not hamper the performance of the engine.

[WHX?? 46,633]

Put up a pic of that exhaust port I have a couple of ideas to  run by you but would need to see if it would work.

Measure the id of it too.  

Edited May 15, 2017 by WHX11

[Racinbob 10,256]

The id on my K91 was spot on for a 1/2: NPT. It actually taps very easily. I ran a taper tap in as far as I could then followed up with a bottom tap to remove some of the taper allowing the the threads to run in deeper. I immediately went to 3/4". As Achto said, the little bit of restriction won't hurt a thing.

 

BTW, make sure you stuff a oily rag in the port first. It will help keep the chips out and drag some with it when you pull it out. Make sure every chip is cleaned out.

[RJ Hamner 992]

I was having my afternoon cup of coffee and ran across a Briggs and Stratton "muffler adapter" part # 690776  (amazon/Jacks Small Engine)

Anybody ever tried one of these on the non-Wheel Horse Kohler K91???

Granted its not too expensive and probably returnable, but thought I'd ask before I hit the "add to cart" button

[Racinbob 10,256]

It would be interesting to see if it would work. I'm wondering about the hole spacing and also if it would extend out a bit far for the support at the steering tower.

[RJ Hamner 992]

I guess if the elbow didn't tighten down far enough a fella could always shorten the nipple

[953 nut 51,407]

1 hour ago, RJ Hamner said:

I guess if the elbow didn't tighten down far enough a fella could always shorten the nipple

You could use a steel electrical conduit lock nut to tighten the elbow in place. Buy it at an electrical supply house, not the bog box junk.

https://www.mscdirect.com/browse/tnpla/54061304?cid=ppc-google-New+-+Lighting+%26+Electrical+-+PLA_sk69grBlc___164124449207_c_S&mkwid=sk69grBlc|dc&pcrid=1641244

[Walleye 28]

@RJ Hamner - I am looking for a flange to NPT adapter, for the same scenario. I decided to grab a piece of plate, cut to fit, and weld a pipe nipple to it. Maybe I'll make one for you. 

 

On 5/15/2017 at 11:30 AM, ACman said:

You could go the flange route or tap it with a 1/2" N.P.T . 

 

If if your not comfortable with this a good machine shop could do this and even open it up to 3/4" like the original blocks had .

In the research I have done, there is not sufficient material around the exhaust port to tap a flanged K90/K91 block to 3/4" NPT. The blocks are different castings and there is not enough material around the exhaust port for a 3/4" NPT to be drilled and tapped on a flanged block. Highly recommended to NOT go 3/4" NPT, and instead go 1/2" NPT. 

 

[Racinbob 10,256]

At least that's what it looked like on my block. Going to 3/4" would have gotten into the stud holes. I fretted over the exhaust port for some time. I had never tapped one out and was hesitant fearing I would ruin the block.. I pondered flanges, searched the internet and paced to and fro the garage looking at it. Once I got the nerve up I had to chuckle at how easily it tapped. My tap wrench wouldn't hold that size tap so I made one from angle iron to allow me to get even pressure on two sides of the tap. It just felt better doing that rather than using a wrench on it.

[RJ Hamner 992]

Well the B&S muffler adapter arrived in the mail today.  It does not look like it will work.  The studs on the B&S are farther apart. Ya pays your money, ya takes your chances.

So.......Mr. Walleye what is the going rate for a custom crafted exhaust thingee???