Hi All,
I have a 1971 coupe with the base 350 in it. I bought the car 6 months ago and it has hooker side pipes. It sounds great but it is very loud. I am not mechanically inclined so when I brought the car to my mechanic for general maintenance and his recommendation was to get rid of the side pipes. He said it is an old school setup where the manifold doesn't meet/cross and they stopped doing this setup in the mid 70s. He said it creates the popping noise you hear while driving it and burns extra fuel. Any truth to this? Thank you in advance

 

Time for hip-waders

 

A) you need a new "mechanic";
B) Hooker had two different "inserts" for their side pipes, The glass packed, "straight through" inserts were notably louder, but produced more power. The "reverse flow" inserts were quieter.

Headers will "burn more fuel", usually, because you're tempted to get on the throttle, due to the thrill of the increased performance.

 

I have mine on.

 

Now that I've caught my breath ...

Your 1971 corvette came from factory with "true dual" exhausts ... meaning for each bank (left & right) of its V8 motor ... it had a separate exhaust pipe-muffler-tailpipe aka tip for the left bank ... and a discrete system mirrors on the right side. Hence Dual Exhaust. Moreover, because the two systems did Not merge into nor meet or cross over one another they are TRUE duals. Your hooker side exhaust are also an example of true duals.

With its OE true dual system, your 1971 corvette's motor ran just fine without any merging, meeting or crossing.

True duals were commonplace until advent of relatively expensive EPA mandated catalytic convertor in 1975.

Single, merged exhausts with a crossover had been used in single-exhaust V8 in lower-performance vehicles prior to 1975.

Single, merged exhausts with crossover became the norm with the advent of expensive catalytic convertor ... one pricey convertor and only one or two pricey oxygen sensor(s). True dual exhausts has two pricey convertors and at least two if not four pricey oxygen sensors.

Current EPA regs mandate manufacturers warranty entire emissions control system for 100,000 miles; wasn't always so.

Perhaps your mechanic hasn't the chops to adequately maintain/tune a carbureted car which has no OBDII port to tell him what's up?
Not unusual; fuel injection has replaced carbs beginning over thirty years ago along with some form of OBD.
Imagine how many mechanics began a career with OBD and have since retired.

 

Is the problem just loudness? There may be exceptions to this, but many of the sidepipe inserts are interchangeable. As long as you have 4 inch pipes that slide/bolt on at the turn just behind the front wheels, you should be able to put in quieter inserts.

Read this forum for real-world examples (everyone has an opinion). I'm looking forward to seeing how "too loud" my sidepipes are when I get them installed (the PO's words when I bought them off of Craigslist). I may consider spiral inserts from http://spiralturbobaffles.com/

Post some pictures!

 

Thank you for all of your help. I gather from these responses especially Jackson's that it is more of a preference then anything. My mechanic has been working on cars for over 50 years and specializes in older vehicles. I think he is just not into the look and/or sound. Cheers!

 

Some people love side pipes while some do not. They do not cause popping or use extra fuel. Sound is subjective so without more information it is hard to know what you are dealing with. There are quieter muffler inserts out there but they take power away. Might not be a concern for you?

If you do not like them then take them off and install an under car system.

 

You need to read up on side pipes and header science. Your mech was right about somethings he just might not of explained it very well

Typical side pipes are nothing more than a loud free flowing exhaust. They have no thought about tuned lengths or even work as a performance enhancement. As you install as mentioned above inserts to quiet them down you are even loosing more power

They are a poor performance idea from the pre 70s

 

Read up on Side pipes and the cool "look" they provide comes with some serious TRADE OFFS.

Hooker Headers and side pipes come with large 1.875" primary tubes........this is an IDEAL size "IF" you're running enough motor to justify them. I won't chime in with exactly what # specifically is the point at which a 1.875 Primary is preferable to the 1.75 or 1.625" that is more typical for SBC primary tubes but you can rest assured its a number well above and way beyond anything close to stock small block power.

Beyond this thought.......there is the not small issue of NOISE....... a quick blast around the block every now and then with open headers and extension pipes might be fun but it gets old pretty quick. Inserts....they can quiet things down to a livable level but when you read up on the horse power and torque loss.......I'm betting you suddenly come to the realization of why more than 19 out of 20 C3 Corvettes still on the road today run the exhaust under the car rather than on the sides.

 

If you decide to keep the side pipes and want less noise below is a link to the quiet mufflers. Your mechanic may find it difficult to remove the side pipe if he has not done this process before.
https://www.summitracing.com/parts/hok-21002hkr

 

If you like the looks of sidepipes you can try different inserts. I know Doug's sells three different types for different 'loudness'. I had the middle ones and they sounded great but I wanted more flow so now I am running the STS spirals. They sound great but are pretty loud! Defintely trial and error!

 

I guess this has morphed into a "sidepipes or not" thread.

If you decide to go to an undercar system, the time to rebuild your rear suspension, prop shaft, parking brake, and differential, is Now. There is a crazy amount of room under the car with the exhaust removed.

Is a stainless, tuned header, out the back with an X-pipe, custom fabbed with full welds and mandrel bends better than sidepipes? Sure! But what you have is free, and making it a bit quieter will only cost a bit of HP, plus the price of inserts and installation.

 

That's how I'm now reading it.

I'd thought this was about an apparent misfire ("popping") & rich condition ("burns extra fuel") ... and a "mechanic" advised that caused by exhaust having no crossover.

I happen to like sidepipes and undercar; had both. Perhaps a great deal of folk who don't like sidepipes do so because sidepipes do scorch a lot of ankles & calves and tend to be loud (for any number of reasons above ad nauseam).

 

I have shortened STS spiral baffles in Stahl 1.75" primary 3.5" secondary headers with short sidepipes. Honestly doesn't feel like I lost anything with those installed. Have been driving it like this for months now, but I also wear a WWII style aviator hat while driving for a bit of muffling.

 

Its mostly a preference thing like you said. For a street vehicle neither side pipes or a full exhaust or even a full dual exhaust with a crossover (H/X pipe) will have no noticeable performance difference with all things being equal for 99% of us. Now the cars that get choked down into a single pipe for the OEM converter they would see a benefit of going side pipe/full dual/dual with a crossover but that wasn’t the question.

Personally i hate side pipes from an ascetic standpoint. I also dislike that the business end of exhaust is only about 24” from my sniffer and my left ear.