K91

[drscooby 0]

HOW HARD IS IT TO CONVERT FROM ORIGINAL MUFFLER TO A TAIL PIPE EXHAUST AND MUFFLER

[Racinbob 10,370]

I'm assuming that your exhaust port isn't threaded? It's not difficult to tap it 1/2"NPT but care must be taken to keep the shavings out of the engine. In the past I've made adapter plates that utilize the original studs and have the hole tapped in that. It was just easier to do that way.   

[Jake Kuhn 1,547]

Bob is right, just wanted to add in, if you purchase or borrow a tap make sure and get a straight one and not a tapered one. I bought a tapered one and ended up having to cut it because it would hit after only about 3 threads the correct size.

[Racinbob 10,370]

Excellent point Jake. I forgot about that. Drscooby, that's critical if you decide to tap the block. The 1/2" NPT tap I have is tapered but by tapping the bolt on adapter off the motor it allows me to run it past the taper.

[AMC RULES 36,954]

Not hard...use one of these. 

https://www.google.com/search?q=1/2+pipe+tap&espv=2&biw=1366&bih=643&source=lnms&tbm=isch&sa=X&ei=om2dVN_DBYuegwT0loL4CA&ved=0CAcQ_AUoAg

[Racinbob 10,370]

A bit more info that may be helpful. The typical 1/2" pipe size tap will be 1/2-14 NPT. That is a tapered tap and the thread issue in a blind hole can be the result. A 1/2-14 NPS tap is a straight tap. I'm not a machinist by any stretch but I'm thinking the ideal thing to do if you want to tap the block is to first use a NPT tap and then follow up with a NPS tap.

[VinsRJ 721]

I typically find that a 1/2-14 NPT provides enough threads for a stock RJ/Suburban exhaust.