The Stovebolt Site Forums The Shop Area Engine Shop Exhaust Q 235 in 46

Question: Is there any exhaust pipe support to the engine before the pipe goes below the frame to head back to muffler?…

current 2” OD exh on mine is supported by the manifold flange and only a single strap after the muffler, muffler has turn down before rear axel.

Tomorrow my truck goes to the exhaust shop for at least a new flanged pipe down off manifold. The current flared flange exh pipe was loose (again) and the donut is compromised, note the prev installer did not put an exh donut sleeve in the pipe to keep the gasket aligned and stop it from collapsing inward. (search corvette exhaust donut sleeve if you are curious). Shop intends to redo new flange w/sleeve w/offset below exh flange as possible to clear steering / sector adj screw.

This is a 46 1/2 ton w 54 235 engine, ex manifold is the 54 (3835587) that exits at slight angle to rear, orig 46 manifold points straight down I believe….
The existing exh down pipe is dented to clear the steering box sector adjust screw, and it is not that much of a gap. I notice a notch in the engine pan flange which looks like the pipe should go nearer to there…
Any routing or other support options I should consider?

Chuck

Originally there was a special strap that clamped around the muffler and held it to a bracket attached to the frame.

My truck has an exhaust hanger in that location and another hanger at the tailpipe where the original hanger was located. This is attached to the frame.

I have used an extra long oil pan bolt (1/4-20) with a nut on top of the flange where the pan attaches. This bolt secures a clamp I fabricated that captures the down pipe and secures it to theengine via the 1/4-20 bolt with the nut. That fixture keeps the pipe from working against the manifold flange and breaking the gasket. Without this, when the engine rocks in the frame it stresses the pipe because it's secured to the frame, hopefully with fabric exhaust pipe mounts. That said, the factory mount for the tail pipe on my truck is rigid.

I believe cars used the donut type gasket while trucks used a flat gasket sandwiched between a flat manifold flange and a flat pipe flange. At least that's the way al the truck engines I have are configured.Either way it's important that the pipe not work against the manifold. There is a thick graphite gasket you can get that prevents leakage due to the extra fire from a truck engine. I have used this successfully for the last couple of years. You need to buy the Cadillac application for 2" pipe. I do not remember the vendor's name at the moment.


I believe there was a factory provision for securing the down pipe to the engine on some years. If you're going for factory originality perhaps one of the parts-book gurus can find a factory part that you can copy.

1Ton, like the ideal of the extended pan bolt mounting point, thanks
By the numbers yes I think this engine originated in a car…..hence the donut….the bottom of the exh manifold definitely has an inner taper like it can accept a donut….
I’m not comfortable going to the frame as engine & frame move on different frequencies.

Chuck

I'm not a parts book guru by any means but, the Factory Assembly manual shows only two points of support for the entire exhaust system.

The first point of support is a strap around the muffler that attaches to the frame via a bracket. The second point of support is a standard exhaust hanger that attaches to the frame just before the tailpipe turndown.

My truck does not have the original muffler strap and bracket but has an exhaust hanger just before the muffler. The second hanger is in the factory location at the tailpipe.

My install got postponed to Monday, will discuss with the muffler shop but factory is usually a good way to start,

curious though, I see the muffler strap on the usual sites, presume the strap folds in the the loop bolt, what I can’t visualize is how/ what is used to connect/hang it off the cross frame. I don’t have an assembly manual, and I don’t see it in the shop manual…

Chuck

Does your truck still have the bracket that the muffler attaches to?

Somewhere around here is a link to the factory Assembly Manual. I can try to take a photo of the page and post it or send it to you. PM me with your phone number and I'll text the photo to you.

No remnants on my truck Otto, PM sent

Computer and Phone aren't cooperating. Just turn your head sideways.

Here's a couple pics of the muffler bracket on my '51 3100. It's riveted to the crossmember and has a curved portion to fit the muffler with a strap and tightening bolt around the muffler.
The Filling Station sells a replacement HERE but it says it attaches to the frame rail. It doesn't look exactly like my original, but would probably work. You'd need a strap and draw bolt to go with it.

Otto - Chucks truck is a '46 so the FAM (1947-54) I think you are referring him to isn't going to help.

Chuck, Below is a pic I took from my 1929-46 Chevy Master Parts Price List with the only diagram of the complete exhaust system in that book. There are close up details showing the hanger pieces at the rear of the muffler attaching to the frame and the tail pipe parts mounted to the rear frame cross member. Hope this may help you get the info you need to show the muffler shop how things were originally.

Dan, You're correct. I didn't realize he had a '46.
My muffler has a bracket built into the back of it that could be used for a strap type support. Or a modern tailpipe hanger could be used. Your diagram shows a hanger at the rear of the muffler with a bracket bolted to the crossmember gusset at the rear of the cab (if the 46 frame is similar to the AD series.)

Good grief. I didn't even notice that. Similar, though.

Thanks Kevin and Otto.

Chuck - I "think" (been known to be wrong a time or too - lol), but the below pictured Rear Tail Pipe Hanger looks decidedly like the item in the parts book diagram. If nothing else, it might prove useful to show your exhaust shop to see about fabricating a rear hanger.

All these pix give me a good understanding of the factory design and intent
I’m surprised that strap around the muffler and mount looks so rigid……something has to give when the engine torques around

Chuck

The rubber grommets on the bracket and rubber on the tailpipe hanger should allow enough play to avoid damaging the flange attachment.