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Nailing Down The Buick Nailhead

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Like
the Small Block Chevy, the Rocket 88 Olds, the Ford Flathead and the Chrysler
Hemi, the Buick Nailhead engine is one of those that has the immortal smell of
history all over it.

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Yet,
unlike its more familiar brothers, cousins and even competitors, the Nailhead
has an aura of mystery about it as well.

 

The
Nailhead had a big-bore, short-stroke design that offered tremendous torque, spread
out over a wide RPM range. Introduced in 1953, the overhead valve Buick design
incorporated vertical valves (the small size of which gave rise to its somewhat uncomplimentary nickname of ?“Nailhead”) and a pent-roof combustion chamber. With its
small valves and tight intake and exhaust ports, Buick used a very interesting
camshaft as its stock offereing, with higher lift and longer duration. The
distributors were in the rear and the starters were on the driver’s side,
unlike later Buick engines.

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Built
from 1953 through 1966, the Nailhead family included a variety of displacements
including 264 c.i.d., 322 c.i.d., 364 c.i.d., 401 c.i.d. and 425 c.i.d.
variations. There were other size Buick engines produced as well that resembled
the Nailheads?(such as the 215 and 300 V8s), but they had no parts
interchangeability with the Nailhead and instead are actually more closely
related to the V6 and later Buick V8.

 

Confused
yet??To clarify the history of these popular – yet often misunderstood
– engines, I spoke with one of the true Nailhead experts in the country.
Russell Martin, owner of Centerville Auto Repair in Grass Valley, CA, says “The
reason few people know much about these engines is because there is so much to
know. I have been amazed by the many changes made during the time the Nailhead
was used from 1953-1966.”

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The
Nailhead was campaigned perhaps most famously by “TV” Tommy Ivo, who raced a
twin-Nailhead (placed side-by-side) dragster as well as a radical four-engine,
four-wheel drive dragster named “The Showboat.” So what was it about the
Nailhead that makes understanding it so difficult?

 

 “For
years I heard guys ask what is so good about a Nailhead: ‘It has those small
ports and valves!’” says Martin. “But they always ran better than they should.
After doing a lot of research, here’s what I found: The less timing advance
needed  in an engine means it has a good combustion camber design; the
Nailhead has the least timing advance (30 degrees) that I know of and the spark
plug is right in the middle of the chamber for a short flame travel.

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“The
blocks have a tall deck height for a good rod stroke ratio (the taller block
allows for a longer rod). The short stroke lets the engine spin quicker than a
longer stroke engine. Smokey Yunick tried to get Chevy to correct this on the
SB for years because its deck is way too short to use long enough rods for
getting the most power,” Martin explains.

 

Other
features pointed out by Martin: the small bearing sizes mean the bearings run
cooler and need less oil. Every Nailhead, not just the high performance models,
had forged rods and cranks. Rocker arm shafts are much stronger than studs with
rockers on them. The whole valvetrain is very light so softer valve springs can
be used for less engine wear and quicker revs.

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The
small exhaust valve heads don’t have as much pressure against them when they
are being opened, meaning less preasure againt them when they are being opened
.Cracks are rare in a Nailhead cylinder head,” he says. “And they rarely leak
oil because of the way the valve covers are designed.” The ports are smaller
than most HP engines but designed with high velocity.

 

Of
course, great design does not always mean simple – and in the Nailhead’s case
that’s a fact you’ll have to come to grips with. First off, the Nailhead is
more correctly labeled a THEM than an IT. According the Marin, the sheer number
of variations can be staggering.

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“The
reason few know much about these engines is because there is so much to know, I
have been amazed by the many changes made during the Nailhead’s existence,”
Martin says. “The 1953 322 is a separate motor, with a special block, heads and
pistons, etc., but the 1954-’55 and ’56 engines also have many differences,
both with the 322 but also with the 1954-’55 264 engine as well. The 322 was
also re-designed and used in large GMC and Chevy trucks from 1956-1959 – this
version of the engine was called the Torque Master.”

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He
continues: “There were three (plus high and low compression models) 364 engines
made from 1957-1961, with  3 different blocks, different con rods, heads
and timing cover, rockerarms, and even starters! Buick made four different 401
engines, three of which have different blocks. Plus, there were two different
425s.”

 

The
important thing an engine builder looking at this powerplant should do is find
the correct year before starting the rebuild. “Certain engines cannot be used
in some Buick cars because of bellhousing, engine mount, block, oil pan and
crankshaft changes,” Martin explains. “Plus, since all Nailhead engines were
externally balanced, mixing dampers and flywheels with some models is not going
to work.”

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Getting
your balance with a the Buick is critical. “Because all Nailheads are
externally balanced, the flywheel/flexplate must be installed with the index
holes lined up,” Martin explains. “They can bolt on six different ways but only
one way will be vibration-free! The 1957-’66 Engines MUST have their dampers
tightened to 225 lbs ft. or the crank and damper will be damaged. They are a
light press fit so the bolt must be this tight.”

 

Cylinder
Heads

Nailhead
cylinder heads are very sensitive, explains Martin, who suggests allowing only
experts in the engine to port your heads – you can actually lose horsepower if
the job is done incorrectly, he explains. The best Nailhead porter I know is
Mike Lewis of Pro-Tech, out of Fresno, CA,” Martin says. “He has spent months
perfecting the technique of porting Nailheads and can improve flow by 25
percent.”

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While
rodders often turn their noses up at the word “stock,” Martin points out that
the stock Buick cam is hotter than the smallest Isky cam and with stiffer
springs will rev to 5500 rpm. “If you want a bigger cam make sure it has at
least 214 degrees duration at .050? or you are just wasting money on a HP cam,”
he says.

 

“If
you are using an aftermarket performance cam, ALWAYS degree in the cam,” Martin
cautions. “This is very important – do not skip this part of the build. I have
timing sets with 9 positions so I can correct any cam that is off. When not
using adjustable rockers we always use adjustable push rods, put the adjusts
down in the valley for easy adjustments, with a hydraulic cam you are only
going to do this once.”

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Additionally,
valve springs are critical. “I have the correct size high performance valve springs
in several spring pressures including a special spring for stock cams,” says
Martin. “The spring pockets in the heads must NEVER be made deeper or enlarged,
because doing so will put the spring into the push rod hole!”

 

The
early 264-322 heads (up to mid-1955) have a very small pushrod hole that should
be enlarged if a larger cam is used, explains Martin. All 1959-1966 364, 401
and 425 heads have the same ports and valve size; the 1957-’58 heads are the
same with smaller valves. However, he says the ’53-’56 heads are different
every year. “Back in the day, hot rodders would swap the early round exhaust
port heads for the ’57-’66 rectangular port heads for racing, custom pistons
and intakes were needed. I had Mike Lewis flow a ’55 264/322 head for me and even
with the smaller ’53-’56 ports and valves they were still only 10% less than
the ’57-’66 heads!”

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Understanding
the Nailhead’s valve seat requirements is very important, warns Martin. “You
should never install hardened seats. The coolant passages are too close to the
seats, so you are likely to either cut into the coolant passage while cutting
for the seat or the metal will crack while installing them! There are a handful
of Nailhead guys who can do it, but guess what? You don’t need hard seats.
These heads have a high nickel content along with small, lightweight valves and
soft valve springs. I have rarely seen bad seats and the ’54-’58 heads can just
use larger valves from later engines as needed.”

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Martin
says valve guides require another caution. “Don’t use anything but cast iron
guides unless you are using roller rockers,” he explains. “The stock short
rocker arms eat up bronze guides in a short time.”

 

Valve
seals were only used in 1966 and on the intake guides only. Martin says you can
add them to all Nailheads but never install exhaust valve seals. “Very little
oil is going to enter the exhaust guide and you need it so the it does not run
too dry.”

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The
newest style head gaskets aren’t necessarily appropriate for these engines,
warns Martin. “Without the right gaskets, engines can leak oil front and rear
of the gasket from the oil passages that feed oil to the rockers. The gaskets
should have a raised circle around the oil passage hole but without it and the
way modern gaskets are made from layers of material these tend to leak. I have
tried sealers but now we use vintage style or factory steel gaskets with no
problems.”

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The
process of building a Nailhead, Martin says, starts with a thorough cleaning
and deburring of the block. “This makes the block stronger so cracks can’t
start and makes it easier to install the cam bearing without cutting your
fingers on the casting flash around the lifter bosses plus if a piece of
casting flash breaks off later it can ruin your engine. These engine blocks
rarely crack but if they do, the crack is usually hidden by the starter. Before
buying any of these engines, remove the starter and look at the block closely
in this area. There are ways of repairing this but none are cheap, another
block is the best way to go.”

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Martin
next pulls the oil galley plugs and cleans the passages. “I use a dent puller
to pull the first one so I can knock the others out with a long rod. We’ve had
the correct oil galley plugs made; all that was available was 5/8? and that is
.015? too large! I use two plugs on the galley hole behind the distributor –
there is enough room without blocking oil passages unlike the 3 front plugs –
and apply green threadlocker on all of them.”

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Next,
the engine gets squared up by decking. “I bore and hone it with a honing plate.
The honing plate, distorts the cylinders just like when the heads are torqued
down so the cylinder will be perfectly round when the engine is together,”
Martin says.

 

All
clearances are kept as close to factory specs as possible. Martin says he
prefers to use the factory Buick oil pumps, whenever possible to prevent
binding of aftermarket units that can occur unless the mounting holes are
opened up and the pump is moved around until it doesn’t bind. “There are
rebuild kits available,” says Martin, “so I rebuild the factory ones and pack
with petroleum jelly.”

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Martin
says the next step is to have the assembly balanced and then assemble it with
oil (or assembly lube), NOT grease. “Grease can plug oil galleys and ruin your
fresh Nailhead.”

 

He
continues: “Before installing the crank we install the rubber rear main seal.
We have had some problems with these seals, not because the seal is bad but
because some blocks have shallower seal grooves machined in them than others.
This causes seal distortion when the cap is torqued down. If the seal lip looks
distorted grind the seal ends a small amount where they butt and re-check the
seal.”

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The
next step is to install the bearings and crank can be installed. The crank
should spin smoothly by hand. “To date I have had only one Nailhead that needed
line boring of the main bores,” says Martin. “Line honing is not an option with
these blocks, because you can’t control how the material is removed. Boring
lets the machinist control where the metal is removed so a minimum metal is
removed from the block – most is taken from the main caps. If the crank is
brought closer to the cam you will get a loose timing chain and you don’t want
that, there are no oversized sprockets available to tighten the chain back up.”

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When
installing the pistons always oil rings and space the end gaps on the top two
rings.

 

Martin
recommends that engine builders stake the front oil galley plugs. “Tapping for
screw-in plugs is not a good choice for these engines,” he explains. “There is
not enough room, you can block off oil passage holes and/or cam sprocket will
not clear them. I have never even heard of a cup plug falling out of one of
these engines.

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Martin
explains how on a recent Nailhead build, he used a rear sump pan along with a
custom oil pump pickup with a larger tube. “Using this pan gave me some free
horsepower – you don’t want the crank and rods being slowed down hitting that
oil. The 1965-’66 GS version already has a lower level from the factory because
Buick used a ’57-’61 6-quart pan with only 5 quarts of oil in it."

 

The
hardest part of a Nailhead rebuild, Martin explains, is installing the cam
bearings so he leaves the hard work to someone else. “I have the machine shop
install mine. Always have an old cam for them to use to fit the bearing, and
after you get it home make sure they are installed with the oiling holes lined
up and MAKE SURE THE FRONT BEARING IS IN CORRECTLY. This is a common mistake
and is a real pain to fix after the engine is in the car. If it goes in wrong
you won’t get oil to both lifter galleys. Another common mistake to watch out
for is leaving out the plugs in the oil galley behind the distributor.”

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Next,
all the threaded holes should be tapped and the whole thing should be scrubbed
with soap and water. “Get all the water off quickly and oil the insides,” says
Martin. “Get a paper towel with ATF and clean the grit out of the cylinders.
Keep doing it until they are clean.”

 

When
you ready to assemble, Martin cleans the backs of the bearing and where they
fit with lacquer thinner. “That allows the heat to flow easier from the bearing
into the rod or block, keeping the bearings cooler,” he explains. “The rest of
the short block build process is by the book.”

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For
more information about the Buick Nailhead or Centerville Auto Repair, visit
www.nailheadbuick.com.

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