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