I want to change my exhaust system and I am thinking about headers for my 64 327/365 no a/c. I have an electric fan on my alum rad and this keeps it nice an cool, about 190 - 200. Will the headers up the heat? If not what kind will be best? I am not concerned about looks only not increasing the heat value. thanks :mad

 

Headers won't increase operating temperature any, but they WILL increase underhood temps AND the amount of heat that comes inside the car through the firewall, not to mention all the other PITAs that come along with headers (ground clearance, alternator mounting, exhaust leaks, blown header gaskets, loose header bolts, etc.) :yesnod:

 

Headers will certainly add some power, but I've stayed away because I want to keep a stock look, and also have heard some bad stories. Of course, some folks will tell you they have headers and no problems. Don't think anyone will deny the increased underhood and interior heat, though.

Here's an alternative that will improve performance over the stock exhaust:

1) Dump the heat riser, and if you don't drive in cold weather also get intake gaskets that plug the exhaust cross-over. The heat riser looks like a restriction to me even when open. You can gut the heat riser if you want to keep it for original looks. Plugging the cross-over keeps the intake charge cool.

2) Get 2.5" mandrel bent pipes all the way back. If you look at the stock pipes, you'll see that they crush down into a weird, almost rectangular shape under the cargo area. I got custom-made pipes that keep their diamter all the way back. The guy also told me he had made 3" systems before that went through the cross-member. Ask around to find a shop that makes good-fitting pipes, though. Be advised that 3" exhaust is loud and prone to interior resonance regardless of what kind of muffler is used.

3) Get an X-pipe. A good exhaust shop can fabricate one, or you can pay big bucks to Dr. Gas. If you bring in a picture, the shop can weld one up from mandrel bends even if they've never seen one before. This unites the two sides of the exhaust system and provides a point of wave reflection for better scavenging. Also gives you a very smooth exhaust note at high RPM. Fitting an X under the car is tight, but again a good shop can do it.

4) Get high performance mufflers. There are Dynomax Super Turbos that have exact-fit brackets are rated at 410CFM each. David Vizard recommends 2.2CFM of muffler flow per open-pipe horsepower for lossless muffling, so these fill the bill for all but the hottest 327. Corvette Central's new catalog has exact-fit Magnaflows as a new item. I really like the Super Turbos, they are only slightly louder than stock at idle but sound very nice when you get on it.

This exhaust system is on my '67, and the motor pulls strong all the way to 6500RPM. Peak HP at the wheels is 281 @5700RPM, and only falls off to about 270 @6500RPM. That tells me the exhaust is not restrictive. Check this out, even though it references a F*rd: http://www.carcraft.com/techarticles/69238/
I've read many similar articles.
Here is another interesting site on getting high performance with exhaust manifolds: http://www.castheads.com/exhaust_fol...haust_set.html
His 2-into-1 setup works like an X because he uses a single large diamter pipe coming out. This stuff is for circle track classes that don't allow headers.


[Modified by L79vette, 3:01 AM 2/24/2003]

 

I have the Doug Thorley headers (now Doug's Headers) on my '64 and they fit and look great. After several years I had them de-chromed and ceramic coated and after 10+ years the coating looks like new. The coating holds the heat in the headers and out of the engine bay. (The chrome blued instantly.) Doug's headers are heavy duty (much thicker than the competition especially at the flanges) and the sound level went DOWN from the old rams horn manifolds while the power went up. I also have mandral bent 2-1/2" exhaust tubing (including tips) and maxflow stainless steel mufflers and a 2" crossover pipe in front of the rear axle.

The 2-1/2" tips make the back end of the car look like business!

 

To me, problems with headers seem to fall into the same category as mothballs in the gastank. Everyone has a friend of a friend who has heard of it but no one has firsthand experience. Personally, I have never met anyone who has had major headaches with headers. Sure the bolts loosen up from time to time on some of them. Whenever I check the oil, I just reach in with the wrench and check them. Makes me feel good because it is one of the few things I can do. :lol:

To me, if you are thinking about performance, the very first thing a person should do is get a set of headers. But that's just me. Classic

 

I have a set of Hooker Super Competition (under car) headers on my '66. The fit out of the box was less than ideal. The collectors interfered with the foot box. I called Hooker and they had some photos of what the headers look like installed. They did say they were very close to the foot box in the photos. Beyond that, they were not too sympathetic. Headers for a C2 are not one of their hot selling items.

I ended up having the collectors sawed off and rewelded in a better postion for clearance. I wasn't about to give up on the performance benefits of headers. The Hooker Super Comps are 1 3/4" pipes so they are really designed for a very high-po 327 or a bigger displacement small block.

 

Just a couple weeks ago installed Dynomax JetHot coated headers on my 64. :cool: The only problem I had was the collectors hit the tab for the splash shield on the pass side. Very close on the drivers side. A call to Dynomax and they said the vettes are close due to ground clearance. Hmmm. Anyway I dumped the collectors and had the muff shop make me some custom bent 'donut' flanges. The splash shields had to be modified (cut shorter) to clear the headers and I did have to cut the two splash shield tabs off. :cuss They are very close to the foot wells also, like 1" so I just heat wrapped them, and I'm going to put some heat shielding on the bottom of the foot wells as well. Everything else cleared fine. :cheers:

 

Depending upon the type of driving you are doing, you may not see any power increase with headers and may actually experience a decrease in power. Again, this depends on the type of driving you are doing and the rpm range the car normally operates in. For most street driving, I think headers will result in a decrease in performance.

Think seriously before changing out the stock exhaust manifolds. The stock system designed and installed by GM is an excellent system for all around driving with good performnce and durability.

If you plan on doing a majority of your driving at higher rpms, then you will probably see the most benefit from headers.

 

vette64red:

Sanderson (http://www.sandersonheaders.com/index.htm) makes a cast exhaust manifold (model QP1000), but I have no idea about fitment on your '64. The Sandersons are sort of a "block hugger" type but the outlet location is not too different from the "rams horn". The cast manifolds are probably not as efficient as tube headers, but I used them on my '62 to decrease the heat and noise under the hood plus there was interference with my valve covers with the rams horns. As others have suggested, unless you are doing a lot of high RPM driving, the Rams Horns are hard to beat.
Charles

 

The collector flange on the Thorley headers almost touches the drivers footwell 'glass. I just placed a piece of thick "foil" at that point and have not had any problems. The passager side has plenty of room, though changing the starter is a little harder (but does not necessitate header removal).

I disagree with those who think headers are just for high rpm. A properly designed header boosts torque pretty much across the band, but the greatest gains are made at higher rpms. They also result in improved gas mileage, assuming that you can keep your right foot out of it. And the visual appeal surpasses the rams horms.

 

If you really don't want headers, try "off road" under car mufflers. I don't remember the option number, but others will. they Will increase your HP!
Stock 21/2" Corvette pieces for the big blocks and they don't have the "drumming" sound at your driver's window at speed.

However.............I would go with Hooker side mounts (with mufflers). Way more power, and an agressive, but not offensive sound, at speed.

 

Quote
"The splash shields had to be modified"

IS this for the 63-64 only? On the 65 and up do you have to have this mod as well? I am wondering with the exhaust option if the 65 and up vettes had more room at the areas in question then the pre 65 vettes. There is an area; I have been told (on pre 65 vettes) that had to be cut if you wanted to run side exhaust. I am wondering if there is some physical differences implemented in 65 to accommodate the side exhaust and possibly make a header installation easier, in regards to coupling the headers to side exhaust.

Mark

 

Don't know about all years, just mine. The splash shields would ride the collector flange and inner clip so I used some tin snips and trimmed them to fit and cut off the tab, no big deal really. As for the side pipes, you must remove the fwd triangle shaped body tab for the pipes to fit. Simple job for a hacksaw blade. I saved mine for later install if I want to go back to 'normal' exhaust. You will also have to cut off the attach brackets for your old side covers. Some say you can bend them up to clear the pipes but that wasn't the case for me.

 

Well I can come up with some stories. The Corvette has actually been better than the Chevelle as far as problems go. The biggest one I had was that the alternator mount (on the header) cracked and had to be re-welded.

One my Chevelle it has been another story. First, I had to have smog legal headers, so I got to pay an extra few hundred for AIR fittings and the CARB EO number. These were Hookers. They fit OK, without too many "fixes" to get them in, although they did interfere with the steering column which was weird since there was lots of room there. One side hung almost an inch lower than the other. Since the Chevelle is not at stock height, the header on the passenger side would bottom out at times. This was particularly noticeable at Willow Springs, where it would bottom out at the Apex of Turn 9 (about 80 mph) if I hit the line perfectly.

After a few years of this, the collector had worn away almost through the bolt, the bottom tubes were dented, and some exaust leaks had started. So I swapped to a set of Heddmans and one of them was defective as installed. Warranty was great, but I had to do the full swap all over again. These are not coated, so underhood temps are higher than before which also causes some problems. I've also been through a few gaskets at the head and at the collector.

All that said, I will have headers on all my performance cars as the troubles are worth the extra Torque, Horsepower, and sound!