exhaust questions

[panteramatt]

My 69 has stock? exhaust. Sounds like crap, kinda like a truck. Its only 2" also. It has a stock 351 windsor with an auto. Eventually will stroke it to a 408 with a 150 shot but for now will only have a smaller carb and intake. I want a low bigblock rumble. I have a couple exhuast ?'s:

1. Long or shorty headers and what brand?
2. Muffler suggestions
3. Which h-pipe?
4. Will 2 1/2" exhaust support my eventual 408?
5. Would I have clearance issues if I go with a aod?

 

[daveSanborn]

You'll find many different answers to your questions, but here are mine:



1. Long or shorty headers and what brand?

Shorty/JBA's are nice, but check the Summit catalog for a similar (likely cheaper) substitute.

2. Muffler suggestions

SpinTech Sportsman's produce a very nice sound.

3. Which h-pipe?

Have your local muffler shop cut/fab an H-pipe onto your exhaust pipes.... no need for any special kit/part.

4. Will 2 1/2" exhaust support my eventual 408?

Yes, and it won't likely cause any routing/clearance issues.

5. Would I have clearance issues if I go with a aod?

Not with Shorties, but you could with some Long-tubes.


It's my opinion that long-tube headers are best used on anything but a daily driver. When you've got $35,000 wrapped up in a purpose built performance motor and you want it to perform to it's utmost ability, use long-tube headers. When you're running pump gas through a Holley/Edelbrock/Ford carb, don't waste your time dealing with any of the headaches that long-tube headers bring to the table.

 

[PJ Moran]

1. Long or shorty headers and what brand?

What Dave said - full length headers are not worth the grief on a street car. Find a set of shorties for a 351W in your car. I hear Sandersons are nice, but maybe pricey.

2. Muffler suggestions

I have the MagnaFlow kit on my car. Aside from the considerable modification needed to fit a convertible, it's a nice kit. Sounds great. I prefer an H-pipe over the supplied X-pipe, and had my muffler guy take care of that.

3. Which h-pipe?

What Dave said.

4. Will 2 1/2" exhaust support my eventual 408?

Easily.

5. Would I have clearance issues if I go with an AOD?

Only if you run full-length headers. FPA are the only ones I know of that will clear (they worked for me). If you get the right shorties, you should be able to route your exhaust pipe about any way you want for a nice fit and good ground clearance.

After modding my MagnaFlow kit to fit my car, my muffler guy said he could have bent the whole system easier and faster himself. But, it wouldn't be stainless or mandrel bent...

 

[panteramatt]

So shorties it is. Are there any good coated ones that arent too expensive? What would the sound and power difference be between h-pipe and true duals straight back?

 

[PJ Moran]

What would the sound and power difference be between h-pipe and true duals straight back?

In my case, we originally replaced the X-pipe with straight pipes. The system was too loud and sounded like a pickup truck on glasspacks. It had a fart can sound.

I went back and had the H-pipe installed. It quited it down some and virtually killed that farty sound. It's great, now.

So, I'd say you need to run an H-pipe.

 

[panteramatt]

Very good info. Ok, so what shorties will work with power steering? What h-pipe will work with my current auto and work if I swap to a aod? Thinking of using spintechs for mufflers. Also, where can I get the rolled dual tips that work on 2 1/2 pipe?

 

[daveSanborn]

Very good info. Ok, so what shorties will work with power steering? What h-pipe will work with my current auto and work if I swap to a aod? Thinking of using spintechs for mufflers. Also, where can I get the rolled dual tips that work on 2 1/2 pipe?

My son is using JBA headers on his Power Steering 351W motor'ed '68 FB. Not sure of the PN, but JBA should be able to tell you. No, they were not cheap.

H-Pipe.... The placement/location of the H-pipe may change when swapping from a C4 to an AOD. You may just want to add the H-pipe on after you've made the AOD swap. Understand that you don't need to buy any special material/kit for an H-pipe. Bring your car to a muffler shop.... get it up on the lift.... determine the best fitting location to connect the L&R exhaust pipes.... have the muffler shop install a bridge pipe that connects the L&R pipes and viola`.... H-pipe.

 

[panteramatt]

Does it matter where the connection is made?

 

[garner67]

Just a quick note on SpinTech mufflers.

I installed a pair of SpinTech Sportsman mufflers on my car (351w ~425hp @ fw), and I really liked the sound. However, they are definitely loud... a little too loud for every day street driving or long road trips.

So I purchased a pair of Dynatech Ultra Flo mufflers, and I really like the quieter sound. The Dynatechs do really open up under wide open throttle, but they are definitely more quiet at low RPMs. I thought about going with Magnaflows, I don't really like the Magnaflow sound; they're a just a bit too "poppy" or "raspy" for me.

 

[sigtauenus]

What are the issues with long tube headers?

Are you guys talking difficulty installing them or performance/driveability issues after they are in?

 

[apollard]

What are the issues with long tube headers?

Are you guys talking difficulty installing them or performance/driveability issues after they are in?

Tough to fit it all around the AOD/AODE/4R70W series trans. I took a look at it since I'm going 4R70W - you either need to drop them low (ground clearance issues) or there are several places that have 1/4 inch or so of clearance.

 

[daveSanborn]

What are the issues with long tube headers?

Are you guys talking difficulty installing them or performance/driveability issues after they are in?

It's not that every car will have issues with long tube headers, but more often than not long tube headers will have some kind of problem where shorties won't have any problems at all. Whether it be ground clearance issues, fitment around the steering gearbox, power steering pump, z-bar or transmission... rarely will a set of long tubes fit perfectly.

The difference in performance between long tubes and shorties is negligible. Since there's no real performance difference, why subject yourself to any of the possible long tube issues?

IMO, long tube headers are for the guy who brings his car/motor to the dyno quarterly to squeeze every last ounce of power out of his engine. Shorties are for guys who are happy with 325 HP and aren't going to lose any sleep devising ways to get to 328 HP.

 

[johnpro]

Keep in mind that the 351w will raise your exhaust 1" all by itself. I have 2.5" exhaust behind Hooker Comps (note: these are NOT Super Comps). I didn't even have to use a drop bracket for the power steering, and I know others that had the same experience.

The only issues I had was getting the headers past he McCleod scatter sheild.

 

[tarafied1]

I have Magnaflows and I'm not sure if I like the sound, but I don't have an H or X pipe either. They are much quieter than the Flowmaster 40's I had.

I also switched from a "long tube" type header to shortys (FPA). They didn't seam (seat of the pants) to hurt performance but sure made the car more drivable!!!
before

after