Macadoo

Hey folks,
I bought a Dynomax exhaust system (the price was right) but I've never upgraded a single exhaust. I'd like to get to it this weekend and was hoping for some tips, tricks, pitfalls to watch for, etc.
I installed Hedman shorty headers and they came with [down cones?] but I'll need pipe from the cones to the system.
I'll be using clamps instead of welding. Will I need to do any drilling for hangers and such? I have a good floor jack and two jack stands, is that do-able? Not really sure where to start.

Here's the system:

http://shop.advanceautoparts.com/p/d...023/20201129-P

Thanks

47 Convertible

Start by getting two additional two or three-ton rated jack stands. Your car needs to be up as high on both ends as you can safely get it. You want to mock up the exhaust without clamping or drilling first to see where the problem areas are. When you are satisfied things will go into place stop there. You apparently need to have some exhaust from headers to what you bought custom built. Use some flex exhaust pipe and bend it to fit on ea. side. Take that to muffler shop to have solid pipe formed. Also take a short piece of what you bought with you plus one of the headers to the shop plus so they can tell what size it is and how much to bump up or down so you can get a sliding fit.

Yes you will most likely have to do some drilling and have a supply of self tapping bolts for frame side along with a sturdy drill. It looks like you have hangers. So reassemble the exhaust system, drill and fasten the hangers using rubber mounts they hopefully furnished, to cushion against rattles. The last thing to do is clamp the pieces of pipe. When you do, clamp them once, then loosen and turn 90 deg. and tighten again. Be sure to use lock washers everywhere as exhausts vibrate like crazy and fasteners will loosen if you don't.
Jerry

joe_padavano

That's a great price for that system. The "cones" are called reducers, as they reduce from the 3" or 3.5" collectors down to the 2.5" or smaller exhaust pipes. I've never had to drill anything to mount a custom exhaust system on an A-body. Just use the factory-style hangers. These are available from all the repro parts houses.



The wide hangers bolt to the frame crossmember just in front of the rear axle and grab the outlet pipes on the mufflers. If you are using 2.5" pipe and clamps, you'll need to slot the holes in the hanger to accept the wider clamp. This puts the mufflers in the stock location, though if you are using 14" turbo mufflers you'll need to extend the head pipes a little.

As for clamps, these are by far the best:





You can get them everywhere now - Advance, NAPA, RockAuto, etc. The straight ones are used to butt pipe together. The stepped ones are used where you have a slip fit (like into the muffler). Of course you'll still need a few conventional U-bolts for the exhaust hangers.

Macadoo

It was a good price, and I had a 30% off good customer coupon that I used as well. Hard to pass it up at that price.

If I only need two of each of the clamps, they came with the system so I think I'm good. I also think I know where to get a couple more used jack stands (I kinda figured this one). I do have the 14" mufflers so roughly how much more length will I need and can I just add that to the bends I have to have made?
Thanks for the tips, and thank you 47 for the flex pipe and clamping procedure tips. I wouldn't have thought of the flex pipe. That's a pretty slick solution. Joe, I've looked at those clamps online but didn't realize they are locally available. Thanks.

1970-W30

Around here you can get a much better bang for your buck by using an independent muffler shop to make the dual exhaust system for less money and no unsightly leak prone clamps to put up with. Plus my muffler shop allows me to poke around under the car while it's up in the air and to inspect their work. That Advance Auto Parts system has 10 clamps, are you sure you want that?

RandyS

Wow, prices are really great there............ I got a quote for a 2 1/2" header back system from a local reputable muffler shop about 2 months ago and they wanted $450.00 for aluminized steel tubing. I installed a Pypes 2 1/2" Stainless system for less than that including mufflers & 18" Slant Chrome Tips. All welded.
I do have to agree that a fully welded system is going to look better under the car......... just my .03 (adjusted for inflation)

joe_padavano

This has been my experience also. Plus, few muffler shops have mandrel benders. The Dynomax system in the first post is mandrel bent.

1970-W30

Anybody know the price difference between the aluminized steel tubing and regular exhaust pipe? The work I had done was with 2 1/4 regular pipe and Dynomax mufflers. In my opinion, 2.5 and up exhaust is overkill for street use, remember the factory W30 engines came with only 2" tailpipes stock.....I'll see if I can dig up the dyno rear wheel test article on stock and mild upgrade engines tested with different sized exhaust pipe diameters, but if I recall there is very little to be gained for the most part for street use. Just my .02 cents....

Macadoo

Trust me fellas, if I could take it to a shop, I would. But I'd have to do my "first start" with open headers and I'd rather be able to hear what's happening, you know? I was kind of hoping the clamps would be temporary. I bought a MIG setup but haven't had time to play yet. Plus my helmet is on backorder until August.

Macadoo

These gaskets go between the collector and the reducer, yes? Is this the correct positioning, over the flare not between the flare and the umm, er....[triangular bracket with three holes]?

[IMG][/IMG]

RandyS

Yes, the gasket goes between the header outlet and the reducer inlet.

Macadoo

Thanks Randy

RandyS

You are welcome. Best of luck!

76olds

Good luck with your exhaust Mac, I hope it works out for you. I don't think the collectors will go very well with the short headers. The shop that did mine couldn't use them as the pipes would have been way too low. I hope you have better luck with yours. The driver side will be the challenge if your 71 is anything like my 76

Macadoo

The reducers that came with the exhaust system were like a foot long! Luckily the ones that came with the headers were much better. Still kinda low but good enough.
My real problem is that the jokers at the muffler shop spread the ends of the downpipes way too much. I was down to the last joint but I just couldn't get it closed. Breaker bar on the clamp until I was afraid it would snap and it still went clanky clank. Obviously I'll have to take it back but in the mean time, is there any way to crimp that end a little? Maybe saw into the steel, perpendicular to the opening, in a couple of spots? Maybe a couple of kerfs would help it close up.

76olds

Did they swage it out way big ? If so you can sleeve it but you will need the muffler shop to give you a piece that will compensate for the mistake they made. If you have on old style U-bolt clamp you may be able to tighten it up to draw it in until you get it to the muffler shop so they can fix it. the old tomato can sleeve shim may be a decent temporary fix. I really like those cragars and BFG's awesome look.

Macadoo

Lol, Did I post a pic of the new wheels? They do look great.
Hey Eric, just how low do your down pipes hang. I didn't notice but mine are way too low. If I let it down off the jack stands I'm guessing I'll be maybe 6" from the floor, if I'm lucky. I just need them to re-bend new pipe.

Macadoo

Oh duh, the jack stand thread. Right right. Can't really see the Cragars though. I'll get some pics up after I get her running.

76olds

My front pipes are tucked up but I had an exhaust shop do mine, They didn't use the reducers.... Instead they made up a small piece with a bend from the header flange and then welded a pipe directly onto the fabricated pipe so no swagging required. It cost a bit up here but I couldn't have done it myself. I hope they can get your front pipes better for you. You should have no problems with the passenger side I would think.