- General Information




For pipes, most shops that custom bend use aluminized pipe. Most pre-bent pipe is mild steel, which rots out after a couple of years.

[ Thanks to Andy Green for this information ]

Dual Exhaust Using Crossover Exhaust Manifolds

All 1964 to 1972 small blocks used the same exhaust manifolds for dual and single exhaust applications. Only the big block cars used different manifolds. There even wasn't a separate one for the W-31's. The small block exhaust manifold used a cover plate over the crossover outlet for dual exhausts. There is no small block dual exhaust manifold.

Find a muffler shop that will cap the extra outlet on a crossover type manifold. It might take a while to find a shop that will do it, and do it right.

Have a muffler shop bend some pipe (preferrably aluminized for durability) to go under the oil pan (like a regular exhaust crossover pipe), and out toward the back of the car, sort of parallel to the existing single exhaust pipe.

Running the pipe, from the driver side, under the transmission crossmember, requires a little denting of the pipe. It will look and work just fine. If you are concerned about a small amount of ground clearance and under car looks, you might cut and weld in an arch to except duals.

Crossover Outlet Cover Plate

The crossover outlet cover placte part is officially called "Cap, Right Exhaust Manifold Cover", part number 386498, used from 1965 to 1971. In 1972, this became part number 382636, as listed in the 1972 assembly manual as "cap - N10 only". N10 was the dual exhaust code option. These parts have been since discontinued by GM.

As a source, try a GMC or Chevy truck dealership. The 5.7 diesels in these trucks ran duals with the same manifolds that cars used. They also had these caps on the RH manifold. This also means that Detroit-Diesel-Allison is a place to look, because they took over supporting the Olds diesel.

Making a Crossover Outlet Cover Plate

There are flanges that hold the exhaust head pipes up to the dumps on exhaust manifolds on any car, right... The exhaust head pipe passes through this flange. The flange forces the flared end of the head pipe against a doughnut gasket forming a seal with the dump on the exhaust manifold. Ok, any muffler shop should be able to provide you with one of these flanges.

Have your local welding shop weld a round piece of steel over the hole in the head pipe flange (where the head pipe would pass through. Presto, you have your cap. Then use an exhaust doughnut gasket between your new cap and the crossover outlet, bolt it up and you are done.

The muffler shop offered to cut the cross over pipe and weld the crimped end. For a much cleaner installation I chose to fabricate a cap. I went to the local auto parts store and bought a new cross over pipe. I then cut the pipe about two inches from the end. I took this piece to a local metal working shop. They turned down a piece of 2" bar stock on a lathe to the inside diameter of the pipe, pressed it in and welded it together. This makes for a much cleaner installation and besides no exhaust gas is going to burn through 1" bar stock.

[ Thanks to Stephen Hoover, Glenn, Jim Chermack, Art Fuller, Graham Stewart, Paul Hartlieb, Tony Waldner, Cliff Feiler, John Gene for this information ]

Exhaust "H" Pipe

The H cross over pipe is definitely good. It's effects were to lower peak horsepower just a bit (like 5 out of 400 that they had) and raise torque by just a bit (like 10ft/lbs). It lowered peak hp by a few hundred RPM (their test engine was a really hi-revving big block) and peak torque by a few RPM too. It mellowed out the exhaust tone and will probably increase exhaust system lifespan.

The H-pipe should be placed as far forward as possible where the exhaust is hot (like right behind the header collectors). Spray the pipe with white paint and take the car for a run to find that hot spot.


You may think headers are worth the trouble for a street engine, but I don't think so. But hey, each to his own. I will open mine up at the strip once in a while this year. If it wasn't for that I would have installed the manifolds. It can be tough to hear your car when racing someone with open headers. I bought the Ultra-Seal gaskets for the header to head connection and Uni-Seal donuts for the header to exhaust. I hope to reduce the maintenence on these two items. As far as re-tightening goes, it is a ritual when checking the oil.

Yes, ground clearance is reduced. Yes, you will scrape when you pull a Dukes of Hazzard. Yes, you will have to periodically tighten the bolts and replace the collector gaskets. You also have to check the oil and change it every so often, tune the car up, and perform other routine maintenance. I've never had any problems changing the oil filter (except for the fact that the primary tubes run directly under the dripping filter fitting, resulting in a few seconds of oil smoke upon startup).

Yes, you need to remove the oil filter adapter when installing the headers, but not when just changing the filter (at least, not with the headers I've used). Yes, you will need to drop the starter to install the headers. And I will admit that the latest set (second generation Kenne-Bell) don't clear the clutch linkage as well as I would like. But, come on. There is no way that the stock manifolds (W/Z notwithstanding) will flow as well as headers. It's just a part of the cost of playing the game.

By the way, I've found two coatings which work very well on headers. Aluminum sprayed headers work very well on a daily driver. The aluminum coating is somewhat forgiving to being knicked, and looks good even when oil is spilled on it. Porcelain coatings look phenomenal, but are considerably more fragile. I had a set on a car which was kept outdoors (OK, outdoors in So Cal) for almost seven years, and the porcelain looked almost as good as when the coating was new. Note that this was not a daily driver. I've not yet tried a set with the HPC Jet Hot coating, but I've heard good things.

[ Thanks to Dave Wyatt, Joe Padavano for this information ]


I'm not certain of your particular application, but several catalogs I've seen list headers that fit such and such Olds, but won't work with column shift standard transmission.

This is due to the linkage running from the column shifter to the trans. I think this primarily applies to automatics. Note that this is the same equalizer link which connects the shifter to the steering column lock on post-69 floor shift AT cars and which must be removed to install headers in a post-69 AT car. It is unrelated to the clutch equalizer on MT cars. The AT linkage equalizer shaft runs between the shift lever on the transmission and the driver's side frame rail about under the front door post. The MT clutch equalizer runs from the back of the block to a bracket on the frame roughly under the brake master cylinder. I have a set of Kenne-Bell headers on my 70 W-30 and the clutch equalizer does not fit well at all. I had to shim the frame bracket and still run into problems at certain points in the clutch adjustment.

[ Thanks to Joe Padavano for this information ]


Collectors are also an issue. I recommend Hooker collectors for any brand of header. I found that these collectors retain a seal years longer than others even with ordinary collector gaskets. The last thing you want to do is weld the exhaust pipe/colletor/header all together to avoid leaks.

[ Thanks to John Schumacher for this informaton ]


Fel-Pro makes a good Hi-performance header gasket that I have been using for years. They are expensive, but don't leak or blow out, and they come off in one piece and don't leave parts on the header or head. Ordinary header gaskets fail often and are no contest to even a back-fire. I've been running fel-pro metal combination gaskets for over three years on Cyclone headers with no leaks/burn or replacement yet.

NAPA Nitroseal also work well.

If you are using any RTV, try Ultra Copper sealant and follow the instructions. I was skeptical when a neighbor told me to use silicone on my header and flange gaskets. Again, it's not SUPPOSED to work because of the high temperatures, but it really works great. The type of silicone doesn't matter. I just use whatever color matches best!

[ Thanks to Jack Wendel for this informaton ]


Dynomax (formerly Blackjack) on a '70 442: The headers, the d*mn things hang down lower than the old set, I didn't notice this when I was under the car at home. I lightley scraped the right one while taking a tight left hand curve.

Hooker Super Comps: They were the only company that made headers for a stick car that would fit, and they still needed a small amount of modification.

Hedman's are ok, but there's more than a little surgery involved to get them to fit right.

Like a lot of you, I've had lots of fun finding a set of headers that fit out of the box with no additional modifications. If you have a 65-72 BB 442/Cutlass, buy a set of EAGLE Headers (A division of Mr. Gasket). A perfect fit with plenty of clearance for the starter and oil filter! In fact, I didn't even have to lift the engine.

Installation Tips

When I dropped in my 425 big block, I had one HELL of a time getting the headers to fit right. It might be a possibility that you will have a hard time to. To avoid this, try dropping the engine in with the headers bolted up. It will make it harder to fasten the motor mounts, but it will still be easier than pushing them up from underneath. My big block is in my '70 olds. Also, You may have to bend in one of the header primaries on the drivers side of the engine as it may knock the steering column when the engine torques while going around a turn. Watch for this and take it careful when doing the first test drive.

I don't think that is possible. I think you have to put the engine in first & then you can bolt up the headers. Floor shift autos are the easiest to work around. Be prepared to move your starter wires. You'll have to route them down from the firewall.

Before installing the motor lay the headers in the engine compartment where they belong, then jimmy the motor in. If you try to put the motor in with the hearders bolted to it, you will have a very hard time getting the motor on the mounts. Just make sure you have the starter and oil filter all bolted to the engine also. Putting them on afterwards isn't much fun once the hearders are on!

You'll have to get the engine back in to put the headers on. They can't be installed on the engine, and then put into the car. Likewise, you can't put the headers into the body and then install the engine. At least you won't have the starter, oil filter, & exhaust manifolds to take off as they are already off.

As for protecting the coated headers during installation, put the headers into trash bags, install the headers, then rip the bags off. Or, wrap them tightly in an old sheet and use masking tape to keep the sheet on. This will prevent them from being scratched when installing them, especially the driver side (when setting the starter on it). After they are on, you can cut the sheet off, making sure you get all of it off.

[ Thanks to Mat Nadrofsky, Paul Rousseau, Bill Culp, Joe Padavano for this information ]

Keeping Bolts Tight

I had a similar situation with a mid-1970's International Harvester 392 V8. The exhaust would come loose in a few days, and needed to be tightened. I think that that engine had a harmonic vibration that just shook the fasteners loose. I tried pal nuts, double pal nuts, double brass nuts all to no avail. One day I got tired of the problem and removed the exhaust manifolds, drilled the studs, and put on castellated nuts with cotter pins; end of problem.

I would suggest drilling your bolts, adding an attachment stud to the header flange, and use a cotter pin or safety wire tie to keep it tight, the cotter pin seemingly the best. It might be a bit of extra work at installation, but worth it in agrivation (sp).

Get Summit Racing's stainless steel header bolts. They have a reduced head size (7/16" wrench size) that makes it easier to get a wrench on them.

I've always just used red Loctite. You can also use the blue stuff. Never had a problem. If you read the spec sheet, the temperatures experienced are really past the operating range of Loctite, so it loses SOME of it's holding strength. That's why I can get away with using the red stuff (stud and bearing mount) yet still remove the bolts later.

[ Thanks to Cliff Feiler for this information ]

Making them Fit

The headers will ding but you have to get them very hot. These are the instructions I got from Doug Thorley. I got out the old gas torches and heated slowly on the area till almost glowing, and then hammered a spot to clear the starter.

I had a '73 VC w/455 & AC. My problem wasn't the AC when it came to headers, but the starter and body braces at the lower rear of the engine area. The body braces had to be discarded & the starter removal was a chore. The starter had to be removed annually because of high heat destroying the solonoid. At ordinary rpm's, I saw no advantage either even though I had changed to a '70 442 camshaft, Edlebrock intake, Holley carb, & CD package for the recurved distributor.

[ Thanks to Bill Culp for this information ]

Routine Maintenence

To get the oil filter off, I found a cheapie ($3) oil filter wrench at the local discount auto parts store that just has a thin (1/2 inch) curved arm that has teeth cut into it. Then there is a smaller pivoting arm that bites into the filter. This is the only wrench I have found that will fit.


For a smaller starter, I contacted the Hamburger Co.(a division of Mr. Gasket). They have a starter they say will work, because they claim the mounting block is adjustable. I did try another aftermarket hi-perf hi-torque mini starter, but the solenoid is clocked away from the engine block, causing a bigger interference problem. I called others and they have the same design, except the Hamburger brand.

1979 Cutlass

This should apply to 1978 to 1988 Cutlass'. I used Hedman Headers, model number 58070. They are a nice header, but do require some work to install them.

The easiest side to install is the passenger. I have found that if the oil filter housing is removed, the header will slide right up into place as long as the car is up on jack stands. If you are installing the engine for the first time and have pre-oiled it, you will probably want to set the header in first and then the engine. This will save you the grief of removing the housing and having oil drip everywhere. Besides, it is more important to keep the oil passages air free when firing up the engine for the first time.

The driver side is a little more tricky. If the engine is allready in the car, the header and starter will have to be installed at the same time. I usually hold the header in one hand and set the starter on the header and carefully lift the two of them in place. I then start the bolts for the starter and then bolt the header in place. The upper A-arm can sometimes interfere if there is alot of shims in it, but this can be solved be removing some of the material with a grinder. Tubular upper A-arms would solve this but they are a bit pricey. If you only have a few shims, this shouldn't be a problem at all. You can also set the header in the frame first if you want but it is sometimes hard to keep the two headers out of the way while setting the engine in.

One thing to keep in mind is that these headers do not dump straight back. Both are pitched at different angles. I used Torque Tech's 3" pipes and they sell a special setup for this type of problem, but you must have access to a welder. It took me a while to put the exhaust on but it was worth the time and effort. Headers themselves are a major project but I definetly think they are worth it.

One more thing to think about is the cross member. For some unknown reason, G-bodies used an offset cross member that only has a single hump. A dual hump one from a late 60's or early 70's GM (Cutlass, etc.) will work great if you remove 1" from both sides. It will have to set on the bottom of the frame rails instead of the top but it will work just right for the where the headers dump. I used one from an '73 442 and it works great. I have 3" all the way back with no clearance problems at all. If you want to retain the original cross memeber, 2 ½" pipes will fit under it on the driver side, but they will be close.

1985 Cutlass with a 455

I am using the 3203s. The long and short of it is that they do seal, but your block placement has to be exact. For the #7 & #8 tubes to not hit the frame rails, the frame needed to be re-drilled for the motor mount pads.

Best way to install them is:
Dropping the transmission down is the most useful move you can make. Have the block out or lifted 2-3". Remove trans cross member and drop the tranny down 3 to 4 inches. Don't seperate the trans and the engine; it doesn't gain you anything. I spent 5 hours stripping header bolts before I realized "Hey there's just not enough room to wiggle these things, I wonder what would happen if I droppped the motor and transmission down?"

Insert the headers from the underside; mate them up from front to rear for the #7 and #8 tubes: dry fit them and cut the fiberglass fenderwell to get them in. The #7 and 8 are seperate so don't drive them into the collector too far or they won't seal. A rubber mallet worked fine for me. Remove the catylitic convertor heat shield if they touch at all at the collector.

[ Thanks to Tom Millard, Brian Kennedy for this information ]

Transmission Crossmembers

Even though your car is equipped with single exhaust, it may have a dual hump crossmember. This only applies to pre 1975 cars. 1975 and after, a catalytic converter was mandatory, and all cars had a single exhaust. Even ones with dual outlets. In order to save money, only one crossmember, designed for a single exhaust, was used. OTOH, an earlier crossmember can be adapted to be used in a later chassis.

[ Thanks to Bob Barry for this information ]