WheelHorse79 271 #1 Posted March 28, 2016 I am replacing the incorrect Briggs on my RJ-58 with a more "correct" K91. However the exhaust on the K91 does not have a threaded port, but two studs which attach the oval muffler. I need to thread the 1/2" exhaust elbow from the RJ-58 exhaust into the K91. Is there a way to thread the exhaust port of the K91 to do this? I understand that I'll have to cut both of the existing studs off, but that doesn't bother me. Thanks in advance for your replies. Share this post Link to post Share on other sites
ACman 7,655 #2 Posted March 28, 2016 Use standard pipe tape . I have the same issue ,I'm going to make a flang and weld my exhaust pipe to it , and use my studs . 3 Share this post Link to post Share on other sites
N3PUY 1,031 #3 Posted March 28, 2016 Yes, make a manifold and use the studs. 1 Share this post Link to post Share on other sites
AMC RULES 37,198 #4 Posted March 28, 2016 Why not just thread the port using a 3/4-14 NPT pipe tap. 2 Share this post Link to post Share on other sites
953 nut 60,251 #5 Posted March 28, 2016 39 minutes ago, AMC RULES said: Why not just thread the port using a 3/4-14 NPT pipe tap. $ Have you priced a 3/4 pipe tap lately, not to mention the 15/16" drill bit. 3 Share this post Link to post Share on other sites
Lane Ranger 11,411 #6 Posted March 28, 2016 (edited) Yes I had my 3/4 tap on a non-tapped Kohler K 91 done for $20 one morning at the local machine shop. I had priced a new 3/4 NPT pipe tap and was surprised how much a new one was. Later found one at a swap meet that was $ 8.oo ! Edited March 28, 2016 by Lane Ranger 1 Share this post Link to post Share on other sites
Racinbob 11,978 #7 Posted March 28, 2016 (edited) No need to go 3/4" That's really pushing things as far as the amount of meat there is. The hole is actually a few thousands over for a 1/2" NPT tap. I used a taper tap (on the right) and followed up with a bottoming tap (in the makeshift tap wrench). That allowed more usable threads but I could have gotten by just fine without it. Stuff an oil soaked rag in the hole and have at it. It taps pretty easily. Just make sure you don't leave any chips behind. To extent the pipe the proper distance to clear the hood stand I used a 1 1/2" long nipple and a 1/2"x3/4" street elbow. Both styles of taps are readily available for under $10 shipped on Ebay. The reduction in pipe size for that short distance is insignificant. Edited March 28, 2016 by Racinbob 7 Share this post Link to post Share on other sites
wallfish 18,191 #8 Posted March 28, 2016 I agree with Bob. Go 1/2 NPT 2 Share this post Link to post Share on other sites
WheelHorse79 271 #9 Posted March 28, 2016 Thanks again for the replies everyone, lots of good advice. I think I will go the 1/2" NPT route. The exhaust plumbed for the Briggs was already 1/2" NPT so I have just about all the parts needed to make it work. I try to find a 1/2" NPT tapered tap. Is this a Lowes, Home Depot or a local hardware store item? Share this post Link to post Share on other sites
elcamino/wheelhorse 9,362 #10 Posted March 28, 2016 (edited) You can get a Lowes , Northern , or whole sets. Or a local Pleasant's Hardware what there name is now. One on Jeff Davis near Dupont or 360 off Courthouse Edited March 28, 2016 by elcamino/wheelhorse added some 1 Share this post Link to post Share on other sites
AMC RULES 37,198 #11 Posted March 28, 2016 There's enough meat there...so either size will work fine... like Bob suggested, just use a tapered tap. NPT taps are sourced pretty cheap all over Ebay. 3 Share this post Link to post Share on other sites
