Ford 300 4.9 3" Inch Exhaust

[ATC King]

I've been through many inline sixes and exhausts, and I've always been stuck with modifying fully welded ones. That changes now.

After digging around for different exhaust products, I found what I needed to build my own without being stuck with whatever the exhaust shop welded up.

There were a couple points that I welded myself, but with a 300 I-6 running unknown headers, that's to be expected.


I'm discovering new drinks right now (Jalapeno Pineapple Margarita) , and I'll leave it with this picture (yes, there's a Supertrapp on it)...

Attachment 267527

[ATC King]

OK, one little snippet...Attachment 267528


Edit: Alright, time to populate this post.

I've been an inline six fan since my first vehicle. Like people who're tired of the current LS swap trend, I was tired of everyone inquiring about what size V8 was in my truck, as if those were the only choices.

The one thing I've come to learn, is it's darn near impossible to build an inline exhaust that sounds good, especially on a stock or mildly built engine. Many of them can sound good at idle or low load, but step on it and that inline cackle comes on. Straight duals? A big neggatory on that one. It sounds bad and is obnoxiously loud to everyone. I screwed up and done that the last go, not realizing just how loud it would be, which is why I added the Supertrapp ends to the duals, which still didn't bring it down to a comfortable level when really ing on it. I do miss the deceleration cackle though, and when shifting gears.

About the best sounding inline six exhaust is a single inlet muffler with dual outlets, using something like a modern OEM truck muffler, to tone down that WOT cackle, which many aftermarket performance mufflers won't do, especially any of the straight core ones. Why am I not doing that? Mostly because of the dual fuel tanks and the extra piping to the left side clutters up the undercarriage more, somewhat getting in the way of easy access to the fuel tank solenoid, if I ever have to roadside repair/replace it. My truck also has a larger capacity, aftermarket rear tank, which doesn't provide exhaust clearance like the right side of it does and forces a tighter bend to be used on the pipe.


It takes some actual installation to find out exactly how a new exhaust is going to sound, and if it's all welded, there's no easy way to change anything. That's why I set out to build a custom, clamped together one for my truck. I also went with 3" pipe for any future engine power upgrades, but it is overkill for the current setup, and massive overkill for a completely stock engine. The last setup was dual 2", which flows less than a single 3".

I needed to use a Y-pipe to mate the headers together and instead of starting from total scratch, I reused the shortest length possible of the original pipe from the collector reducers to the Y-pipe. Inline six headers are a bit of a cluster, and make space a little tight on that side of the engine and frame. Since I was reusing some original pipe, which is 2" aluminized steel, I had a difficult time finding a prefabbed Y-pipe with dual 2" and single 3", which wasn't stainless. I settled on a dual 2.5" to single 3", which meant that stretching the 2" as much as possible and welding it would be more secure than trying to use clamps, because I wouldn't be able to stretch the pipe enough for a tight lap joint.

Attachment 267529Attachment 267530Attachment 267531

I had notched the trans crossmember for the previous exhaust, and I guess that exhaust had a little tension one way, because now it just barely kisses that one pipe, just enough to rattle when taking off or under certain loads.

Before going any further, I need to mention the goal wasn't to do this wasn't to save money or use the cheapest parts available. In all, I think I spent about $350 on the parts. Which isn't bad by any means, though the two largest contributors to that were the Magnaflow cat and Supertrapp end disks.

I did buy a pipe stretcher on Ebay. I'm hoping that'll last through a few jobs or possibly more, so it's cost is rather insignificant when stretched out and it may actually pay for itself in that regard.
Attachment 267532

Some quick notes on the budget priced pipe stretcher. It's built to use an impact, and it needs a strong one to function properly. The first thing I'd suggest is the screw portion copletely apart before the first use, cleaning everything with brake parts cleaner, then putting a coat of good quality grease on it. Then after the first pipe stretch, do that again, and it'll be good for a while. The reason is the machining isn't first rate and there will be a little material removed during break-in. These low cost tools also tend to have machining remnants stuck to them (tiny metal bits), that need removed before the first use. Another thing is it doesn't really stretch very far before having to put the next larger size collar on it, so keep an eye to see if the threads are bottomed out if it seems to stop stretching the pipe at a point. The next size collar will have to be used and it may still be a little fight to get it in. The last thing is to do the stretch in stages, rotating the tool to different angles, which will keep the pipe round and not be such a big fight to stretch the pipe.

Although this stretcher does what it's supposed to, it is slow. This isn't some hydraulically powered, professional pipe stretcher, it's a budget priced tool for the home garage. Again, if done right, it's a slow process, but it did produce good results with patient use. I also done all the initial fitting and stretching off of the truck. On the vehicle, the process is going to rattle the heck out of everything.



Back to the build.

Directly after the Y-pipe, I mounted the catalytic converter.

Attachment 267533Attachment 267534

This is the one joint I'm not satisfied with. The O.D. of the cat and the Y were the same, which meant I needed to stretch one, and also meant I didn't find a lap joint clamp the ideal size, so I used a butt joint clamp and wrapped some aluminum can material around the cat inlet, since it was the smaller one now. I done that, thinking it would allow the clamp to evenly tighten on the two different sized pipes. Nope. I has been leak free though, for about 1,500 miles, so I'm just monitoring it at this point. All joints are sealed with Permatex Ultra Copper.

I only had to use the factory exhaust hangers, which kept things clean and simple. The first hanger was right after the cat and right next to a lap joint clamp (which work great). I only had to bend the stock hanger to the length I needed and attached the exhaust by using a standard style clamp, which I double nutted to keep it from loosening and so I didn't have to tighten it to the point it deformed the pipe.

Attachment 267535


For the middle section of pipe, I bought a straight piece longer than I needed, so I could cut it to length once I was able to test fit parts. Nothing fancy there. I had to go the post office to pick it up though, because it was 7' long and wouldn't fit into their Jeep. Why 7' feet? Because that was the best bargain. A 4' section wasn't saving me much money and I'll have the spare of it for other projects.


The tailpipe is nice, with smooth bends. None of that pipe denting stuff like is normal with the benders many exhaust shops use. It was also very affordable, for about $50 with free shipping. I was very pleased with that.

Attachment 267536Attachment 267537Attachment 267538Attachment 267539Attachment 267543

Yes, it's larger than the driveshaft.

Another lap joint and clamp to the tailpipe. I used a high-temp paint pen and put an index mark across it, to see if anything twist with use.

Attachment 267544Attachment 267545

I have tightened all the clamps and bolts twice. Once after about 30 miles, then again after 1,000. Everything is staying good. The nuts on the clamps are lock type nuts, but still, with heat cycling, things will settle in for a bit.



I initially hoped the cat would quieten it down enough to run straight after that, and for the most part, it took a lot of the harshness out of it and the large diameter pipe on it's own, takes a lot of the ear piercing cackle away from the inline six. The cackle is still there, but it's not glass breaking loud.

At that stage, idle was really deep sounding, and just off it was pretty good too. The problem was at road speed and light load; drone.


The droning was not ignorable, and no way I was going to attempt to live with it. That's when I ordered the Supertrapp end disks. I wanted to put one on it anyway, and trying to fab something to use both the previous 3" ends wasn't possible without it looking bulky and overcomplicated, which was bad, because I knew how much a 5" kit cost. Oh well, bite the bullet, and just order one.

I didn't know if it would stop the drone, but was hoping. I really didn't want to put a regular muffler on it yet, so I'd have to wait to see if the Supertrapp worked it's magic.

Attachment 267546Attachment 267547

It worked! The drone was gone. Phew.

I guess I did weld one more thing, the Supertrapp adapter to the tailpipe.

If it looks too low in the previous picture, that's mostly the picture angle.
Attachment 267548

It could be raised up an inch or so, but the reason for it's current height is suspension droop. I put it on with the rear suspension completely unloaded (hanging down), to make sure the leaf springs wouldn't hit the tailpipe in that situation. I left some wiggle room, but not much. The honking large Supertrapp makes it look lower, but it's high enough to clear parking curbs. I also wanted it sloping downward enough that water wouldn't settle in the last bend.



I think that's about it. I happy with how it turned out. It cleaned up the underside compared to the previous dual exhaust, will allow for future power upgrades, and there's some tuneability with the Supertrapp. I will be adding an air fuel meter sometime this year. When I first put the headers on, I welded O2 bungs into the collectors, so that part is done and I did take out the plugs this last go, to clean the thread and lube them real good with some high-temp anti-seize so I shouldn't be smashing my knuckles on the frame trying to get them out later.




Did you read all that and wonder...all that and no sound video.

Lets be real, unless someone has high quality sound recording equipment, they're not going to capture the true sound. There's a lot of exhaust videos on Youtube, and the majority of them sound as craptastic as the next. Not the exhaust itself, but the quality of the sound recording. I don't have any quality audio recording equipment, so there's no reason to do it. Another thing is, using Flowmaster mufflers as an example, they sound good to a lot of people, but consistently perform poorly in back-to-back dyno comparisons. So, getting an exhaust that sounds good and performs at the top can be pretty dang difficult. I've had a lot of different mufflers and exhausts put on vehicles over the years, and cut just as many off to replace them. At least now I can just unbolt things for a change.

[kiser]

Inline 6's are hard to beat, they run for ever! It's amazing the torque they make compared to a stock small block. It is hard to get them to sound good but it sounds like you have went the right route through experience. What year is your truck?

[big specht]

You know what you need to help cancel the sound…….it’s a TURBO

[ironchop]

Any Dentside Ford truck is cool

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[ATC King]

kiser, it's a '79. It's got the square headlights (jab at the 78/79 headlight debates).


big spect, a turbo would be nice, but if I was going to get the most from it, fuel injection and more precise timing control would be required. Remember the Pontiac 301 turbo or the early Buick 3.8 turbo that still had a carb? Not many do, because they were very conservative on the boost as the systems needed a wide margin or error to be durable enough for Joe public. Oldsmobile has an all aluminum, turbocharged V8 in the 1960's too. That was a not ready for prime time engine (methanol tank empty, pfft, floor it anyway).

Blow through, carb box, draw through, anything with a carb and basic distributor ignition isn't going to be able to safely/efficiently use as much boost as something with FI and modern ignition. While it was fun watching the turbo 292 build on YouTube, done in controlled conditions on a dyno, there isn't enough margin of safety to crank it up for everyday street use. I've been running my electric fans from toggle switches for years (need to fix that), I don't need another manual switching anything to forget to turn on/off so something doesn't go sideways, because I've forgotten those a time or two already.

Besides, for engine longevity with constant spirited driving, there needs to be some very professionally done machining, balancing, and building, which is $$$. Those professional car shows on YouTube don't always divulge total cost, but I could see an inline with that full build treatment getting close to $10,000 for everything start to finish, including initial engine purchase price, especially with paying someone else to do the build and tuning. I did watch an episode or two where boneyard engines got nitrous poured into them until they puked. If a replacement engine is cheap enough...just keep replacing them.

Edit: Just thought of another funny analogy. Some may say the Cummins is an inline six and boosted, and handles it just fine and lasts. Sure, but it's a purpose built diesel engine, much like what's in big trucks. Remember what asking a gas engine to do diesel work gets you...an Olds 350 diesel. Anyway

Maybe...someday. I'm pretty happy with them NA, using bolt on parts, a small bump in compression, and a mild cam. Fuel economy can actually improve over stock, longevity isn't taking a huge hit, and power is still way more than stock. If I miss a gear during WOT, it isn't likely to lubricate the pavement either. The 3" exhaust is in anticipation of modest internal upgrades, but one can hope.

ironchop, YES sir!

[kiser]

Roger that on the '79, it's a good looking truck! I bought my first dent side last fall, it's a '75 highboy bucket truck. I've always had a soft spot for the '67-'72 and '73-'79 Fords.

[big specht]

this is my 69 that has a 300-6 in it with 4.10 gears and a 4 speed it’s like driving a diesel 25mph shift to high and never shift again. Those inline motors do make some good torque

[ATC King]

this is my 69 that has a 300-6 in it with 4.10 gears and a 4 speed it’s like driving a diesel 25mph shift to high and never shift again. Those inline motors do make some good torque

Do you get this very often?:



What rear axle and wheels are those? Full floaters, so that's some type of HD axle and it doesn't look like a 9"


I've never checked my gear ratio, but about 35mph, I'm into fourth. From there to 100+ (GPS, speedo stops well below that), no more shifts. Around 65-70, it really has some giddy up until about 90.

[ironchop]

Those wheels are BADASS

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[ironchop]

I have nearly all the pieces accumulated and ready to rebuild the entire drivetrain, fuel system, suspension, and brakes in my 79. Trying to decide on chassis exit or fenderwell exit headers.


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[big specht]

Do you get this very often?:



What rear axle and wheels are those? Full floaters, so that's some type of HD axle and it doesn't look like a 9"


I've never checked my gear ratio, but about 35mph, I'm into fourth. From there to 100+ (GPS, speedo stops well below that), no more shifts. Around 65-70, it really has some giddy up until about 90.

Lol yea it’s a f250 camper special. It’s a Dana 60 and those are factory wides 16.5-9.75 wide wheels

[Arky-X]

I'm sentimental to those late-70s Fords. Always wanted a 79 with the square headlights.
Got my dad's 76 Ford F-150 when I turned 16 when he bought a new(er) truck. Thought I was something with that 460 under the hood but I had no clue except "bigger carb and louder exhaust" when I was a teenager. Had I known anything at the time, I would have first looked at some gears because I think it was 3.00. It moved ok off the line but you could run 80mph no prob on the highway.......if you could hold it from floating all over the road. Could have fixed that problem too (steering wheel play/slack) had I had any mechanical inclination then.

[ironchop]

BTW Clint, that's some good looking exhaust work. I'm a big fan of those band clamps too.

I was surprised how much aftermarket performance items were available for that powerplant.



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[ironchop]

Roger that on the '79, it's a good looking truck! I bought my first dent side last fall, it's a '75 highboy bucket truck. I've always had a soft spot for the '67-'72 and '73-'79 Fords.

Throw up some pics please

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