Exhaust Manifold -- engine lift?

[mimregi]

i was very tempted by the pics of the coated headers at motorsport -- very sharp.

I am leaning away from new headers at this point, having read this and unearthing a few other threads on the matter. Mine have some silver paint flaking just a teensy bit, but they are not flawed in any obvious way (is there a good way to check for an exhause leak besides just trying to feel for one?).

I'm going to see what the guy at <gulp> meineke (I do have a recommendation from someone here though) has to say, and then make a call.

totally appreciae all the feedback though, extremely helpful.

[mimregi]

Mathew' date=' That system is NLA from MSA. I called about it in May after I had seen and heard it at the MSA show in April. The end pipes are still available in two sizes. FWIW you don't need a header if you're stock. You won't get much out of it and it's much more noisy, and HOT. As far as an exhaust system search under "exhaust system" to see what I did. I went the local muffler shop route and am very happy w/ the outcome. See pics in my gallery.

Cheers, Mike[/quote']

Shame about the Targa system, looked sharp (though I guess teh tips are still out there).

I actually found another thread with some of the details on your job (part of what swayed me). Looking closer at the pics, is that a resonator or a cat in the middle there?

[Ed]

Unless you are planning to do several other modifications to your engine the header will just be money spent on something you really didn't need. There is nothing wrong with the stock cast iron exhaust manifold. It seals better than the header. If you are going to stay mostly stock on the engine stay with the stock manifold and get some new piping made up.

Then on the other hand if this is the first step to additional modifications then the header is the first step. Spend the extra $150 bucks and get ceramic coated or take them to your local powder coater and have some high temp powder coating put on them. Either one will decrease underhood temps and prolong the life of your header. They will look better too.

You could order a pre-bent system but you will probably spend just as much having one custom made and the custom bent one will fit better. I drove my car with only the headers on them to a guy who custom bent 2 1/2 aluminized steel tubing. I went with a resonator along the driveshaft and a Flowmaster exhaust. It is louder than the stock but at idle has been mistaken for a V-8.

When you start working you will probably want to remove your intake manifold as well since it shares 1/2 the bolts it will make everything more accessable and you will need to replace the gasket anyway. I used a little bit of high temp copper sealant on the manifolds to insure a proper seal. My first gasket developed a pinhole and so far with my current gasket it's still sealed.

After you have access to all your studs soak them with some PB Blaster. Also have a torch ready incase you come across one that is a bit tight. Carefully replace all those studs.

Put it all back together and then take it to a shop that can custom bend you a new exhaust. NOT Midas or some other commercial exhaust place. CUSTOM!

Here is a picture of mine:http://www.classiczcars.com/photopost/showphoto.php?photo=18480&cat=500&ppuser=1052

[jjacquot]

I believe they call it a pre muffler in the middle of the exhaust. I have been doing a little bit of research on this same subject. I bought a 73 that I am putting SU carbs, a polished intake, headers, and performance exhaust. I have the stock exhaust off the car. It was rather easy when the intake and carbs are already off. I purchased 3 into 2 headers off of ebay, but I need a collector to go with a single exhaust. From what I have found a custom exhaust will cost about the same as a prefab but you have a local shop to take it to if you have any problems.

[mimregi]

Damn Ed that is a FINE looking automobile!

The more I hear and read, the more I think I am just going to get the exhaust done at a shop. That particular Meineke is the only local recommendation I have gotten for Orlando, but it was from someone on these boards (seerex) so I am going to give them a shot in the am...

[kmack]

Looking closer at the pics, is that a resonator or a cat in the middle there?

It's not a cat., but a pre-muffler or resonator. With both the stock and aftermarket systems, a pre-muffler was used to cut down the resonating from the exhaust pulses. These tend to happen (or be louder) at higher rpm's. Also tones down your exhaust note quite a bit.

Others are right in that if you are staying stock, the stock manifold will be just fine. A header will add a bit (just a little bit) more power in the top end on a fairly stock motor. But it also cuts about 15+ lbs out of the weight of the car. Those stock manifolds are heavy and I had eight stitches in my forehead to prove it (don't ask...). :dead:

The previous system I had on my car was the following:

6-into-2-into-1 header w/ a 2-1/4" collector and 2-1/4" custom mandrel bent exhaust all the back to a generic Turbo muffler (w/ no resonator). It had a mellow tone at idle up to about 3500 rpm. At that point, it started to howl, but not overly loud.

This was on a stock '71 L24, w/ E31 head, SU's and a K&N filter w/ stock airbox. With the airbox in place, it pulled 136 bhp at the wheels. W/o the airbox, it jumped up to 139 bhp. About 800' elevation. But I don't have any info with regards to the stock manifold.

I paid all of $125 for the entire exhaust system installed, minus the header (which I already had).

Talk to a few guys that have custom hot rods and such and find out where they had their exhausts done. They will be able to point you to a good custom shop at a fair price. A system bought from MSA (or any other catalog company for that matter) will have some installation problems. Some minor, some major. It's just easier to go with a custom built system for about the same price. Plus if something goes wrong, you're not just blaming yourself.

[Pop's Z]

Mathew, That middle muffler was(note I say was) an 18" glass-pac turned around to "maximize the flow"(so the muffler guy said). I had it put on in the first place as I had read many threads here and on other sites that if I didn't I would have the dreaded resonating boom at 2000-3000 rpm. I had it removed after a week because the system was too quiet. I do not have any resonance and the system is still quiet, but you can tell there is a high-revving six under the hood(and I don't wizz-off me neighbors). Ed gave you really good advice. I asked the local hot rod guys who they took their cars to and went there. Cheers, Mike

[Arne]

Unless you are planning to do several other modifications to your engine the header will just be money spent on something you really didn't need. There is nothing wrong with the stock cast iron exhaust manifold. It seals better than the header. If you are going to stay mostly stock on the engine stay with the stock manifold and get some new piping made up.

I agree with this in theory, and actually planned to use a stock manifold on my car. However - this is only great advice if you already have a stock manifold that it is really good shape.

My car had (and still has, for now) an '83 L28 in it. P79 head with round ports. I'm going back to a stock L24 which will have square ports. So the 280ZX cast manifold won't work. Which prompted me to begin looking for a stock 240Z manifold. And I found that good ones are darn hard to find.

First, almost all of them have broken and rusted flange studs. Every one I saw needed them to be drilled out and tapped.

Second, many of them still have broken and rusted air injection rails still attached. And as with the flange studs, they are typically rusted solid. Drilling those out is a much more difficult job than the flange studs.

Lastly, how many of us have seen L-series engines with one or both of the exhaust studs at the front and/or rear of the head broken? This apparently happens because over a period of many years the cast manifolds warp. They get a pronounced bow to them and exert downwards pressure on the end studs. Eventually the stud breaks off. Many of the used cast iron manifolds you might come across will be warped in this way. Place a straight-edge along the bottom of the ports and you'll see what I mean.

So after working on all this, drilling, tapping and such on a used manifold that is less warped than many (but still noticeably warped), I'm going to cut my losses and use a header instead. Not for performance so much as to save myself a whole lot of time and effort.

[mimregi]

Those stock manifolds are heavy and I had eight stitches in my forehead to prove it (don't ask...). :dead:

Ouch!

Well the car is at the shop now. I feel pretty good about it -- the guys seemed to know what they were talking about and care, and they didn't have a problem with me walking around under the car with them... which was cool. The only times I have seen the car from that angle, it has been six inches over my face =) I mentioned in the OP that the pipes hang too low -- well the collector comes off the manifold a good ciuple inches lower than it apparently should. I was glad to see it and talk through it with the guy, he was going to raise it up from there back, but talking to him a bit, he is going to just slightly heat bend or maybe even cut the collector to get the whole thing up higher. I was really pretty surprised just how off it was, I suspected it was just a non-original collector, but I fear that the manifold may not be in as great shape as I hope. Once the new pipes are welded in and the muffler is on, we're going to check the seal there... keeping my fingers crossed.

The whole thing is going to run a bit more than I had expected (about $250), but if they do a good job I won't complain. For that money money though, I will be walking under the car with them and being pretty picky about everything.

[kmack]

...and they didn't have a problem with me walking around under the car with them... which was cool.

That's the sign of a good shop.

[mimregi]

Sorry I didnt post yet, but i wanted to wait until I had some pics... which I still don't (and in fact am kicking myself for not having taken some "before" shots).

Man am I pleased... and man am I relieved to be saying that =)

When I first pulled up, I thought that they hadn't finished, because I couldn't see the muffler AT ALL. The guy managed to get a fairly standard sized turbo muffler angled and mounted in such a way that I haven't found an angle from which you can see any part of it without laying on the ground -- even squatting right behind it, it's really well hidden.

I layed down on my chest to see what kind of progress they made with the low-hanging pipe, and there was definitely a difference, but I felt like there was further they could go (still a few inches of clearance left in the canal)... until I looked at it from the side. It's pretty much even with the frame rails (hangs just maybe-but-probably-not-quite half an inch below, as opposed to three or so before I brought it in). He said they also clamped the collector down a bit because it didn't appear to have a good seal (may help explain why the gas smell had gotten so drastically worse all of a sudden; almost certainly related to the big backfire that started it all), though they felt the manifold seal was solid (this was welcomed news).

Welding, bending and mounting all looked good (there was a couple of inches of rod sticking out of one of the joints that I meant to ask about but forgot -- it was neither hanging down nor up into anything it could interfere with, just kind of sticking out sideways into space; I didn't have a good angle on it and havent double checked yet, but I suspect it was part of the mounting), overall I was pretty pleased. Set me back $270, which seems a bit high, but they did do some extra bending and it was solid pipe throughout (no clamps or joints); most importantly the worked seemed good, so I paid it with a smile.

Then I started the car... I had an expectation of what the car would sound like with 2.5" pipe (he talked me into it, I had intended to go 2.25" but I was putting my faith in this dude) and no resonator, and this was not it; this was better than I had expected. I was STUNNED how quiet it was. Sounds strong, not like a civic or anything, but quiet, even at high revs, and this is exactly what I asked for -- I like to drive with the windows open and I still want to hear the music.

Best part: gas smell is GONE. I have driven it about twenty miles and not caught a whiff. It looked to my eyes like they cut the tip a bit short (and I still may extend it some just to protect the hatch), but nothing appears to be getting in the cabin anymore. I still suspect I am running way rich and certainly have a long term project where all the seals on the car are concerned, but right now I am very happy =)

[jjacquot]

Glad to hear you got what you wanted. I am taking my headers to a shop I was referred to today to see what they can do for a collector, while I am there I may see what they can do for the whole thing (headers back.) What is the best, 2.25" with a resonator or 2.5 w/o a resonator? Bear in mind, it is almost completely stock right now, but I have hopes for the future.