MTFCA Forum

Hi all, here's my current challenge... I have a newer exhaust pipe (steel I think) that's 1 1/2" diameter and I discovered (frustratingly) that the new muffler kit I installed today measures 1 3/8" diameter. So I ended up putting the old rusty muffler back on for the time being. Looking for advice on how to figure this out. I'm kinda surprised (but maybe I shouldn't be, given this is a Model T) that this happened.

What muffler kit are you using? FO-11 muffler works great.

Have you considered something like this?

PSJ wrote: ↑

Fri Jul 21, 2023 8:39 pm

Hi all, here's my current challenge... I have a newer exhaust pipe (steel I think) that's 1 1/2" diameter and I discovered (frustratingly) that the new muffler kit I installed today measures 1 3/8" diameter. So I ended up putting the old rusty muffler back on for the time being. Looking for advice on how to figure this out. I'm kinda surprised (but maybe I shouldn't be, given this is a Model T) that this happened.

This muffler isn't from one of the vendors? I would think any muffler they sell would be made to fit the exhaust pipe they sell

Hi Tim, yes from Langs just last week. The matching pipe they sell is 1 1/2" OD, so I'll be calling them on Monday to sort it out. In the meantime, I'll take a look at what Frank suggested about the adapter.

Your description of a "muffler kit" and it not fitting a standard exhaust pipe has me really curious as I've never ever had an issue making these things marry up correctly.

If you'd give a P/N for the "kit" or a picture of it, it is all but certain that your question will be correctly answered almost immediately

I'm suspicious that you have purchased a shell kit for a cast iron end muffler and have perhaps misunderstood how the baffles fit within the cast iron ends - do NOT go expanding or farting with things until you've posted a picture or at least state exactly what kit you bought

I remove the option now that I understand what muffler was in reference

part # 4025A, which matches the muffler type I have on my T now.

Pat, when you get this sorted out, try not to put a clamp on the muffler, allow the pipe freedom to slip in & out as the pipe heats up, a stainless steel pipe will expand more that a regular steel pipe when hot. The pressure with the pipe expanding contributes to pressure that can promote exhaust manifold warpage. George

so, the exhaust pipe will not slide into that nice big empty hole?

I will admit that I have never purchased a complete new repro CI muffler but find it hard to believe it is sold with the wrong sized machined hole...huh.

I'll be watching with interest to see how this shakes out...

PSJ wrote: ↑

Sat Jul 22, 2023 10:31 am

part # 4025A, which matches the muffler type I have on my T now.

Same issue. The cast inlet on the repro early muffler is machined on tight side. Had to take the pipe to the bench grinder and remove some pipe diameter. Took a bit to slim the pipe O.D. To slip fit the muffler inlet.

Pipe was painted before grinding so you can still see ground area. Plus some red grease oozing as had to lube that pipe end to wiggle in place, the muffler was already mounted to the frame! Difficult to grind a perfectly round diameter on a long pipe end with just a 6" bench grinder stone....


But all worked ok, repro parts need attention , but sure nice to have ‘em, can’t go to my Ford dealer for T items!

Hello John,

I'm got 1.509" on the ID of the mufflers we have on the shelf.

Like Dan said paint could be causing an issue. also the old pipe has a bur at the end that is sticking out from being cut it could cause an issue or if the old pipe has been egg shaped with a old exhaust pipe clamp it could cause an issue.

If the muffler is undersized let us know and we can get another one out for you.

Thank You Steve

Hi Steve, thanks for reaching out! I missed your call but am available now for a bit. Otherwise I'll connect with you and your staff on Monday.

It would be nice to see someone with $$$$ remake the 21-27 exhaust pipes again. I did it about a half a dozen years ago, and sold over 50 of them.
I've always been able to find good used originals for myself, but my question is if Ford could make them correctly, with todays technology, why can't it be done again?

I have been & still are impressed with Langs monitoring & reaching out to these posts of possible issues with parts.
Thats truly customer service above & beyond.

Pat

Tom Rootlieb apparently had the same trouble on his muffler on his '09 restoration...perhaps someone at the machine shop mistakenly bored the front hole the same size as the rear hole? He had to rebore his front casting to get things to work.

Rear hole on a cast iron muffler piece accepts a 3/4" pipe tail pipe - front piece should be 1 & 1/2".

Shout out to Steve Lang for taking time to trouble shoot with me this morning - I really appreciate it! I mistakenly said the inlet was 1 3.8", when it's really as Steve said at 1.509" ID. I'll be investing in a set of calipers today. We talked through a few solutions and I'm going to go the route of using a bench grinder to shave down the end of the exhaust pipe just enough to slide it into the muffler inlet. (Dan - thanks for suggestion and pictures!)

Steve did say the repro parts are machined to be a much tighter fit between exhaust pipe and muffler inlet.

Glad you have a path to success and that it is an easy one

the 1 3/8" measurement you posted indicated a much more dramatic and fundamental problem

Yeah Scott that's on me. I apologized to Steve and for the record, there's no problems with the Lang's mufflers. It's the new T owner (me) that is still learning

I recently had the opportunity to ‘build’ a muffler for my ‘14 using ORIGINAL cast ends, tailpipe and 3 bolts. I bought the 3 shells from Lang’s and when the outer large shell had a too-small diameter, I called Steve. He must’ve measured many outer shells from his kits of 3 and sent me an outer shell that fit perfectly !! Thanks Lang’s !!

Whatever fit achieved, it should be a sliding fit to allow the length of the exhaust pipe to expand and contract in length with heat cycles. If it is firm in the rigid cast iron end of the muffler, expansion will load up the manifold end, something to be avoided.
On the later mufflers there was only one mounting bolt, right at the rear. The mounting arm on the pressed steel end was capable of flexing to accommodate the one piece pipe expansion. Cast iron muffler ends will not flex!

Allan from down under.