'71 351C fitting/routing of exhaust outlet pipe over rear axle

Hi,

I have ordered an original style exhaust system for my '71 351C 4V Mach 1. Everything fits nicely except (why is there always an except???) the outlet pipe on the driver side. The problem is, the pipe somehow collides with the brake hose that connects to the rear axle.

Before I start modifying thinks I would like to ask if anyone has pictures that show how the pipe fits over the rear axle. Is it possible that the staggered shock setup contributes to the problem?

Thank you for any help, Manfred

Bumping this back to the top.

I do not personally have any pictures of how the "stock" exhaust is supposed to look as I am running headers on both of my '73s.

I would think the staggered shocks should not be an impediment if you are using a stock system that was designed for it, but stranger things have happened.

Hopefully, someone will be able to submit some pictures for you.

I, of course, am a modifier, so if all else fails, modify!

BT

Here are a few pictures. I hope it helps. Excuse the nasty underside. it is an original car, but the exhaust has been changed many years ago. It is still the original configuration. The staggered shocks should only help as the shock is behind the axle on this side. It is close though. About an inch clearance at the closest spot. Good luck!

Great pictures, thanks. It is quite a close fit as they show. And no need to excuse that a 40 year old car doesn't look like as it came from the factory.

Regards, Manfred

Ok I had the same issues with the same kit, I even went through 2 complete exhaust kits the second was worse then the first.

I can take pictures but First I used a pipe expander, using that with an impact wrench, I opened up the end of the turbo mufflers in the kit I used. This allowed me to slide the pipes further back away from the axle as it's a tight bend.

After doing that I discovered I could clear the brake line but came close to shock and fuel line and fuel sender wiring, plus I discovered I was way too low at the rear valance.

Frustrated I begin shifting things around for days. What finally helped seat things was rotating my mufflers from horizontal to 20 degrees diagonal. Sort of like \ / this angle allowed the mufflers to sit wider on the intermediary pipes and the angle of the outlets in the mufflers was enough to get the tail pipes to sit correctly between the brake line, shock, fuel line, and wiring and rear valance.

Additionally the turn downs in the tail pipes for the Mach 1 chrome extensions do not fit, the turn downs on the pipes are totally wrong, and the reproduction tail pipe chrome tips are totally wrong also.

I used a dermal and I cut the tail pipe tips down so they stuck out from the valance correctly, and had to turn one strap around on the tips to prevent a fuel tank puncture in case of a rear collision.

I fought the thing forever when I was done I ended up having slight exhaust leaks, I had to go back and braze some of the joints, as a kit it sucked. If I have to do it again I would have a custom system made with resonators in the tail pipes.

I will take pics

Ok I had the same issues with the same kit, I even went through 2 complete exhaust kits the second was worse then the first.

I can take pictures but First I used a pipe expander, using that with an impact wrench, I opened up the end of the turbo mufflers in the kit I used. This allowed me to slide the pipes further back away from the axle as it's a tight bend.

After doing that I discovered I could clear the brake line but came close to shock and fuel line and fuel sender wiring, plus I discovered I was way too low at the rear valance.

Frustrated I begin shifting things around for days. What finally helped seat things was rotating my mufflers from horizontal to 20 degrees diagonal. Sort of like \ / this angle allowed the mufflers to sit wider on the intermediary pipes and the angle of the outlets in the mufflers was enough to get the tail pipes to sit correctly between the brake line, shock, fuel line, and wiring and rear valance.

Additionally the turn downs in the tail pipes for the Mach 1 chrome extensions do not fit, the turn downs on the pipes are totally wrong, and the reproduction tail pipe chrome tips are totally wrong also.

I used a dermal and I cut the tail pipe tips down so they stuck out from the valance correctly, and had to turn one strap around on the tips to prevent a fuel tank puncture in case of a rear collision.

I fought the thing forever when I was done I ended up having slight exhaust leaks, I had to go back and braze some of the joints, as a kit it sucked. If I have to do it again I would have a custom system made with resonators in the tail pipes.

I will take pics

Click to expand...

I feel your pain Hcode. Machman

Where did you guys buy your various kits. I have been looking at all of the various catalogs, and I wondered about this very problem, and have not yet ordered from anybody. Has anybody tried the Boss 351 kit offered by anybody? Here's my 71 Boss in progress:

Personally since I bought 3 inch headers I just reduced to 2.5 for the rest of the exhaust and bought tail pipes from flowmaster. Had the bends done at a muffler shop for the alignment from headers to mufflers.Well actually. I brought the car over to the muffler shop and had them put the exhaust together.I had all the parts so all he had to do was bend the pipes and he welded it all.He charged me 220$ for the work.But he did tell me the tail pipes needed to be worked on a little.I figured for the price he was asking it would save me a lot of trouble.From all the people I have talked to there is no kit that fits without some tampering. The bends are never perfect.And by the way he did an amazing job when you look under the car everything is straight and matches up.

I went ahead and ordered the Boss 351 Kit from C.J. Pony Parts, including the H-pipe and hanger kit. They said the fit is guaranteed. They also said that Motive makes the kits for the specific applications and usually the fitment is not an issue.

We shall see. I'll report back after I receive the system. I sure hope it does fit without a lot of issues. -Andy

(Just re-posting, since my previous post was listed as "unregistered")

Where did you guys buy your various kits. I have been looking at all of the various catalogs, and I wondered about this very problem, and have not yet ordered from anybody. Has anybody tried the Boss 351 kit offered by anybody? Here's my 71 Boss in progress:

Click to expand...

(Just re-posting, since my previous post was listed as "unregistered")

I went ahead and ordered the Boss 351 Kit from C.J. Pony Parts, including the H-pipe and hanger kit. They said the fit is guaranteed. They also said that Motive makes the kits for the specific applications and usually the fitment is not an issue.

We shall see. I'll report back after I receive the system. I sure hope it does fit without a lot of issues. -Andy

Click to expand...

Here's the system from C.J. Pony Parts. It's the Motive brand system (there are no markings, but the salesperson said it was made by Motive, as did the salespeople at several other Mustang Parts Vendors, including NPD). This is the Boss 351 specific kit and H-Pipe.

Best deal was at C.J. Pony, at approx $342. with the H-Pipe, and free shipping. The hanger kit was another $72. These prices were including the 10% discount they ran on the weekend a few weeks ago. The H-pipe was backordered (which they said it was on the phone) and took 2 additional weeks for delivery. Everything was well packed and arrived safely by Fed Ex Home Delivery.





I was a little leary of the fit on the Driver's side tailpipe, as it seems to angle in, toward the gas tank. When you pull it over to the hanger, it requires some tilting of the muffler, which others have mentioned in their posts. Remember, the system is laying upside down in the photo, so the Driver's side is on the left when you look at it.



While this is just a dry run, as the motor isn't in place, and pipes can be trimmed or shortened a little and turned as needed, everything seems to fit very well, and that Driver's tailpipe will work, but could've been bent outward about an inch more when the pipe was turned for that particular bend. That would've kept the mufflers flat, and gave more clearance over the axle tunnel. BUT, it's a minor complaint and there is about a finger thickness (3/4") of minimum clearance at the tightest points over the axle.







I will post additional photos after I get the sway bar and shocks in place, as well as the brake lines. I have to order a good fuel tank. If you want to see more of my photos of the restoration so far, you can look at the albums listed under the "1971 Boss 351 Project" at this link http://s271.photobucket.com/home/awhawh/allalbums

-Andy

Finally got around to assembling some of the rear components, shocks, swaybar, axle, springs, hydraulic brake lines, gas tank, rear valance, even painted the inside of the trunk. Fitment of the tailpipes will be close at the rear shackles, and up in the tunnel over the left side of the axle, but I think I will have at least 1 inch clearance at all points, once it is firmly fastened in place.











If you want to see more of the photos, here is the link: (the "sub albums" are shown down on the right side of the page)

http://s271.photobucket.com/albums/jj132/awhawh/1971%20Boss%20351%20Project/?start=all

Happy Holidays ! -Andy

This may be totally wrong,but I will through it out there for what it is worth.Many years ago I ordered an NOS rear brake line (flex hose)for my Mach from Ford,1979 or 1980. If my memory is any good at all I believe there was a differance between a dual exhaust car and the single exhaust.I will have to dig it out to get the part number off of it.

Beautifully dun restoration.

This may be totally wrong,but I will through it out there for what it is worth.Many years ago I ordered an NOS rear brake line (flex hose)for my Mach from Ford,1979 or 1980. If my memory is any good at all I believe there was a differance between a dual exhaust car and the single exhaust.I will have to dig it out to get the part number off of it.

Click to expand...

Hi FastE,

would be great if you could come up with a part number.

- Manfred

Nice car, Great pics of the build.