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Olds FAQ -- Exhaust Manifolds

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Nov 25, 2002, 3:04:38 PM11/25/02

Olds FAQ -- Exhaust Manifolds

Exhaust Manifolds

1949 - 1964 1964 - 1990 1995 - Present

Exhaust Manifolds 1949 - 1964
Identification

Detailed Listing

Exhaust Manifolds 1964 - 1990
The 1969-72 exhaust manifolds feature a divider between the center exhaust
ports. The 1967 and earlier models do not have this feature. Also, all
manifolds except 1970 to 1972 will have a heat riser (shutoff) on the
left-side exhaust manifold.
All Olds small-blocks with dual exhausts used the single-exhaust
right-hand
manifold, with one opening capped off. There are no true dual exhaust
small
block manifolds.
[ Thanks to Kevin Hoopingarner, Bob Barry for this information ]

Identification
The cast-in ID consists of a large [1"] letter or number, usually found at
the
front, over the front exhaust port. On earlier units, it can be found over
the
REAR exhaust port. There is also a 6-digit casting ID, usually somewhere
near
the center.
As per convention, if the big single-character ID is a number rather than
a
letter, that denotes a small block part. It was not uncommon, especially
after
1970, for small block exhaust manifolds, such as 1 and 4 or 5, to be used
on
big block cars. Sometimes you can find dual exhaust manifolds on big cars,
too.
Exhaust manifolds come in many styles, we'll cover the most popular. The
main
difference for the performance enthusiast is whether the center ports are
divided in the manifold, as in the late W and Z units. LH= for left hand
side,
RH= for right hand side of engine.
D, E, G, H, J, K?- Toronado exhaust manifolds. Duals. They typically turn
up
and out at the outlet, far more so than those for any other car. Since
that
would run the exhaust into the frame or body of most cars, these are
useful
mainly for identifying a Toronado engine.
A number of sources have pointed out that there is no difference between
W-30
and 442 exhaust manifolds. An article in JWO explained confirmed this.
NOTE: The W 389268 was not used on the 68 442 as stated in the Supercars
book
and other places. The 68 uses a unique manifold (Y-398706) with heat
shield.
[ Thanks to Chris Witt, Ed Ekstrom, Dan Williams for this information ]

Year ID/ Casting
Used Code Number Application
'65 - '67 X 389269 LH; Cutlass, 442.
W 389268 RH; Cutlass, 442.
'67 - '69 A 384785 LH; full size. 425.
T 39870934 RH; full size. 425.
'68 Cutlass: early 1968 models use same as 1967.
Cutlass: late 1968 models use same as 1969.
'68 T 398708 RH; big block
X 389269 LH; Cutlass, 442, some VC and SX.
Y 398706 RH; Cutlass, 442, some VC and SX.
R LH; full size.
'68 - '70 S 384895 RH; full size. With heat shield to protect
steering box.
'69 - '74 W 402295 LH; Cutlass, 442, W-30, H/O.
'69 - '72 Z 402294 RH; Cutlass, 442, W-30, H/O.
'70 - '?? X 412287 LH: full size, Cutlass.
'73 - '74 X 412287 LH: 442, W-30.

H 411970 RH; Toro.
J 407103 LH; Toro.

1 380001 LH; X-over.
1 411961 LH; No X-over. Straight down. 350 diesel. Gas
also.
1 411981 LH; 350 gas.
'65 2 380145 LH; 330.
3 381921 RH; X-over.
4
'68 - '73 5 398704 RH; X-over. 350. Delta 88.
8 558319 With "Z-Y" underneath the "8".
8 558480 With "H-Y" underneath the "8".
'81 14 22503678 LH; 260.
'81 17 2506300 RH; 260.
3 563619 RH; 350 diesel. Gas also?
[ Thanks to Chris Witt, Kevin Hoopingarner, Mark Prince, Kevin O'Brien, Matt
Cremean for this information ]

Detailed Listing
ID Casting # Side
A 384785 LH
Used on big cars about 1967 to 1969. Single outlet is straight down
in
the center, not good for an A-body car. Companion to T, typically.
H 411970 RH
Toronado.
J 407103 LH
Toronado.
R LH
Used on big cars. ## holes?, exit angle? Might fit in A-bodied cars,
with effort. Companion to T, typically.
T 3987094 RH
Used on big cars about '67-'69. Two holes; one for crossover pipe
from
the LH side. Main outlet has 2-bolt flange angled about 45 degrees
down
and back. Might fit in A-bodied cars, with effort. Companion to A,
typically.
W 389268 RH
1965-67, A-body with big block and dual exhaust. This one has the W
over
the rear runner. Does NOT have a divider between center ports. One
2.5"
outlet, 2-bolt flange, points about straight down. Companion to
X-389269-LH. See also Y-389268-RH [?]
W 402295 LH
1969-72 442, W-30, H/O, A-body with big block and dual exhaust. "W"
is
over the front runner. THE most desirable set to have. Has divider
between center ports. One 2.5" outlet, 2-bolt flange, points about
straight down. Companion to Z-402294-RH.

X 389269 LH
1965-68 442, A-body, some Vista Cruiser and SX's with big block and
dual
exhaust. This one has the W over the *rear* runner. Does NOT have a
divider between center ports. One 2.5" outlet, 2-bolt flange, points
about straight down. Companion to W-389268-RH.
X 412287 LH
1970-up? A-, B-, C-body with big block and dual exhaust. Has the
divider
between center ports. One 2.5" outlet, 2-bolt flange, points about
straight down. Good substitute for W-402295-LH.
X 412287 LH
1973-74 442, W-30 with big block and dual exhaust. Has the divider
between center ports. One 2.5" outlet, 2-bolt flange, points about
straight down. Good substitute for W-402295-LH.
Y 398706 RH
1968 442's, A-body, some Vista Cruiser and SX's with big block and
dual
exhaust. This one has the Y over the front runner. Does NOT have a
divider between center ports. One 2.5" outlet, 2-bolt flange, points
about straight down. The manifold has raised ridges in it and a heat
sheild that rests on them. Companion to X-389269-LH.
Z 402294 RH
1969-74 442, W-30, H/O, A-body with big block and dual exhaust. THE
most
desirable set to have. Has divider between center ports. One 2.5"
outlet, 2-bolt flange, points about straight down. Companion to LH
unit
W-402295 LH.
1 411961
Small block. ?? about divider. ?? about outlet size, 2-bolt flange,
points about straight down. Companion to ?? unit 4-?????? unit.
4
Small block. ?? about divider. ?? about outlet size, 2-bolt flange,
points about straight down. Companion to ?? unit 1-411961.
14 22503678 LH
1981 260 small block with single exhaust. ?? about divider. ?? about
outlet size, 3-bolt flange, points about straight down. Companion to
RH
unit 17-2506300.
17 2506300 RH
1981 260 small block with single exhaust. ?? about divider. ?? about
outlet size, 3-bolt flange, points about straight down. Companion to
LH
unit 14-22503678.

Typical exhaust manifold pairs, left/right, are: X/W, X/Y, W/Z, A/T, R/T,
R/S,
D/E, G/H, J/K, 1/4, 1/5, 14/17
[ Thanks to Chris Witt, Ed Ekstrom, Dan Williams, Mark Prince for this
information ]

Exhaust Manifolds 1995 - Present
Identification

Detailed Listing

General

Parts
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.

Headers
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 ]
Applications
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
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 ]
Gaskets
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 ]
Experiences
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.
Starter
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 ]

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