How-To Section: Build a high perfomance Pinto
High performance pinto
There has been a lot of “mud” slung
at the old Single Over Head Cam ford motor, over the years.
Starting with the rockers being no good and the inlet tract can’t
flow enough air.
I believe these are all inter-related.
Starting with the standard [Std] rockers:
The Std rockers are just fine with Std springs which are about 40
lbs. of pressure at valve closed. Its only when you up-rate the
cam and springs that the Std rockers are stressed. This led the
performance industry to be conservative with cam profiles etc. ,
which in turn, led to achieving less air flow via the port. Materials
have come a long way too. So if you get a cam, get a full kit. Also
try to move away from cam specs of old and try one of the latest
grinds. The major cam manufactures are now producing shafts that
are far superior to old, with relation to ramp speeds etc.
I have had a bit to do with this motor and whilst
mine isn’t the fastest/best HP I can tell you about it and
recommend the combination that will get you at least 180HP. It started
even before I had a car for the engine. I got a used head off of
a friend to modify. This was to be the test mule.
After lots of reading of various books, I had decided
that down-drafting the ports would be the quickest way to more flow.
With this in mind I made a jig to mount the head in a vertical mill,
to bore the ports out at various angles, then to insert a tube that
would be curved to achieve a pipe for the carburetors to bolt onto
after fitting a flange, similar say to a Lotus head. Well this was
all good in theory, however achieving a seal between head and pipe,
inside the port, was to prove elusive, thus far. I did get some
“trick” putty from the states that was on paper the
answer to this, The port at “d” and “c”
in the picture were bored at different angles to see what would
be the best. It became apparent that raising the port roof gave
the best shot at the valve as far as air flow was concerned. This
led me to drill holes around the port to find out how much metal
was able to be removed from the upper port area, as in port “a
“ in picture. I then ground a port out to what I believe to
be a safe limit as in picture “b” . From this a template
However I decided to travel down a different path.
The above is also something for the future. By this time I had a
car with an engine that a reputable engine builder had developed
with filled inlet ports. At about this time a friend purchased a
completed head from a supplier that was said to flow about 200hp
of air. Both heads were fitted with 44 and 38 millimeter [mm] valves
of flat back design. He and I had our heads flowed on a Super Flow
110 Flowbench. My friends purchased head, outflowed my filled port
head, in all areas. I then proceeded to modify the fillings as they
seemed to make the port smaller. This had little affect. The exhaust
ports were ported very similarly in both cases. It is interesting
to note that the recommended port bias Inlet to Exhaust is approximately
75%. This is achieved, leading me to suspect that a smaller exhaust
valve and bigger inlet valve could be used, with more extensive
work preformed on the exhaust port, however at that stage I was
very happy with what I had learned, but certainly something for
I then proceeded to copy friends head, which essentially was ported
with the best shot at the valve when looking down inlet port. I
use an air die grinder to remove material. I have used an electric
one but found it hard to control. The best units have a remote motor
with an extension drive to a chuck system. I don’t have that
much call for one so I make do with what I have collected. Grinding
bits are varied to suit the job. You can buy kits, with all the
parts you need, these days.
I replaced all the valves with ones of same diameter.
Mainly because the valve colletts were worn. This is something to
be aware of when using strong springs and/or inferior valves. One
thing to try to slow down the wear rate is to stop the retainers
and colletts from spinning about the valve. This can be achieved
by grinding the sides of the colletts till there is a gap between
them when they are fitted to valve stem. Also be aware that the
retainer to head distance [spring length] will increase. The new
valves were sourced from England.
I never got to flow the finished head. It is fitted
with a Crane 310-8 cam and their springs and retainers. This is
certainly not the hottest cam around but is suited to the revolutions
that the Std modified rods will withstand. When setting up a head
you must check the wear area on the rockers. This is perhaps the
most important thing to check. The wear area needs to be in the
centre of the cam pad. If the cam runs off the end of the pad it
will wear out very quickly. Placing it away from the centre of the
pad means that the cam profile will be accentuated/de-accentuated.
Machining is needed to correct this situation.
The inlet manifold was moved up on the head so
that bottoms of inlet tracts were almost level. To achieve this
the mounting holes had to be filed to suit. The manifold was then
doweled to the head and finish ported whilst bolted to it. To match
up to the oval shaped port that I described previously would have
ment a new manifold would have to been made. I use bolts to hold
the manifold on as this makes carburetor removal possible with air
cleaners on. I use off the shelf “Genie” brand 4-2-1
extractors. These have had the manifold port upper and side part
of the ground away [matched], to match the port shape. The bottom
is angle ground so that the head to manifold face is lined up but
as it moves away from port it is sloped upward. There is a definite
mismatch to prevent exhaust reversion. The rest of the exhaust consists
of 2.5 inch tubing with a round resonator under the boot floor.
Pinto’s like a high compression ratio. This
may be to aid with a poor combustion shape. Above is all with a
2000cc head so high compression domed TRW 11.5:1 pistons are used.
Even then the head has to be shaved. This engine is running 12.4:1
ratio on 100 octane fuel.
In hind sight it would be best to have flat topped
pistons with say a 1600cc head that achieves the required ratio
through a smaller chamber. This would aid gas flow into the chamber.
The pistons need to be set up so that at the top of the stroke they
are approximately 30 thousandths [thou] of an inch from the head.
I highly recommend a Felpro head gasket. This means that the pistons
will protrude from the block some distance. Approximately 8 thou.
As the compressed height of a Felpro head gasket is 1 millimeter
[38 thou]. This all needs checking at assembly time. Valves need
to be approximately 70 thou from the piston, at all times. The pinto
needs clearance around the spark plug. A groove needs to be in the
piston to aid flame travel. One thing to watch out for at these
levels of compression is the bottoming of the head bolts in the
Conrods in this engine are early style with floating
pins, lightened around the small end with 3mm material left, and
also on the bottom of the big end.. When doing this you need to
lighten the heaviest rod first then work others to this weight .
A 3mm hole needs to be drilled in the top of rod to allow oil to
the piston pin. I use Automotive Racing Products [ARP] Conrod bolts.
This combination has been very reliable for a 7500 rpm limit.
The crankshaft is relatively standard. They have
large radius fillets. I have approx. 3 thou clearance on the rods
and main bearings. This doesn’t seem to adversely affect oil
pressure, though I am using a high volume pump.
The flywheel needs to be as light as practical
and doweled to the crankshaft. I am currently using a slightly modified
Escort sump. Engine was fitted with a Cortina sump that gives more
oil capacity, however there were spacers under the engine mounts
to raise it. Even then the lower part of the sump was below the
cross-member. The escort sump has had the baffle removed and remade.
It is larger in size [fits sump walls better] and the pick up and
dip stick holes have their lips turned down. This combination has
not lost oil pressure on any corners. I also use an oil cooler.
The next step forward here would be a gated sump with extra capacity.
The 2 litre engine oil capacity is relatively low.
Engine is fitted with twin 45mm Webber DCOE. Carburetors.
The carburetor internals fitted to this engine are :-
No. 4.5 Auxiliary venturies
No. 2 Needle valves
No. 40 accelerator pump jets
No. 50 F9 idle jets
No. F2 Emulsion tubes
No. 150 Main jets
No. 195 Air jets
Other Bits and pieces.
I had most of the internal engine parts coated with a kit that I
got from the states. I am unsure of the affect on power that this
will give. I look at it as mainly for durability. I had the springs,
valves , conrods and rockers, pistons and head coated in various
substances as to the kit instructions.
It is essential to set up the cam timing to cam manufacturers specifications.
I use the Esslinger way as it is fool proof. It is also good to
read their assembly instruction before you start.
The cam belt and timing can be a bit tricky, so
beware here too. The valve clearances need to be set at the cam
to rocker junction.
One bit of trouble I have had is the Welch plugs/core
plugs falling out. This could be because of block flex, it is relatively
easy to fix with some small fasteners.
You will need a better starter than the standard
unit. The standard unit really struggles with the added compression,
especially when its hot.
This extra compression also leads to colder spark
plugs. Above motor runs happily on 2 grades colder spark plugs.
You will need a 3 core radiator to prevent overheating.
Please use electronic ignition.
Webber carburetors need about 2 to 4 PSI of fuel
pressure to work effectively. However they need a lot of fuel. You
will need an electric fuel pump and suitable regulator. I use 9.5mm
Please use a rev limiter, other than your right
The above engine will idle at 900 rpm, although it is happier at
1100rpm. It pulls from 2000 rpm in top gear. It has power till 7200
rpm, which is perfect for the conrods in it. When it was dynoed,
the tyres were let down to 8 psi. A mate and I had to sit in the
boot so that the tyres would grip the rollers. The dyno operator
was very happy with the pulling power of it also. All on a Dyno
I would like to hear from people who have some
other ideas, as I am building another engine soon. I have written
above so that new comers to this engine will not be discouraged
from trying to do their own engine.
Pinto engine assembly notes
I have built a few motors in my
time. Haven’t had any failures, yet. However, the outside
work was kept to a minimum.
Let me tell you about the ‘pinto’
engine for my escort.....
Sent it to have machining done.
Gave them a list of things to do, it sat there for 3 weeks till
they decided to do it all in a few days. So pick it up and go home
to start checking it out.... Conrods look funny, surface finish
doesn't look like before. Look at other standard rods I have here.
The machine shop has sand blasted them instead of shot blasting
them. I had already polished & lightened them. Wrote on my job
card to have new bolts fitted, re-sized, small ends floated &
shot blasted after balancing.
So take them back.
About this time I ask why I had them put dowels into crank as I
am dealing with the boss this time. His answer is "because
you asked us to". Words fail me. I point out that they have
a tendency to part company from flywheel, & that they really
should be bigger & more than 2 of them at .25 inch [6 millimetre]
in diameter! He informs me that “they will never break and
are super hard”. Well they ain’t yet, however I will
be taking off slightly easier than I had wished to. Anyhow 3 visits
later on a Saturday morning I wait as he re-sizes conrods after
So now I can dry assemble the engine.
Start with the head. I am using new valves which are slightly longer
than previous, no lash caps this time, so after setting it all up
cam, rockers, springs etc. the cam lobes run off the end of the
exhausts rockers only. Also all the rockers are touching the retainers.
Crane dished retainers [e.g. use longer spring.] ......lots of swearing
After linishing the edges off of
the rockers so they don't touch retainers I am having trouble getting
the correct spring pressure, way too much. Drag brother around so
he can look at it, 2 heads are better than one etc. I suggest to
lower the valve into the chamber by putting exhaust valve seat inserts
into the head. He says that will work and we then set about finding
how much. I have some 1 mm shim which we sit between head and valve.
This seems to about right. However, brother suggests to ask the
experts at the machine shop. So back I go to explain to him what
is happening. He has a vague idea about what I am talking about
and suggests to grind the cam lobes smaller!!. So I asks him to
put inserts into the head, 1 mm further out of the head & to
machine the valve seat pockets the same amount.
I Collect that some days later. Re-assemble it again, near enough
to perfect, well actually some 10 pounds too much pressure at full
lift but hey, what's a guy to do! CC's chambers, work out to achieve
compression ratio needed, I need 40 thou off head, so back it goes
to machine shop again. So all well there, matches manifold to head,
dowel it with a roll pin in manifold, little touch up on the exhaust
seats that he fitted.....wallah!
So onto the bottom end now all
seems ok there . Tons of clearance on bearings. Head bolts are close
to bottoming out into block so get away with tapping them out with
a bottoming tap.
Now off to the coatings place with it all. I had approached him
earlier he is ok to do the job and seems eager to do it as he is
just starting out and wants the experience with engine parts as
people mostly want exhausts etc. coated. Anyhow he gives me a great
deal. So I drop off parts to him. He is quite busy and I don't want
to push him in fear of a shitty job. Anyhow 3 weeks go by, so I
go check him out. He has most of it done & completion will be
by end of that week. I pick it up, to find the cam bearings are
cooked [read melted] & need replacing. He is very apologetic
& says to get new ones & he will coat them, offers a third
off the total price, which I decline as he has done a good job,
so far. Take it all home to find mains & conrod bearings are
missing from package. Too late to go back, so return Monday night
after work, he is sick & no one knows where they are. Employee
rings him to find that they got missed & he will coat them later
in week with new cam bearings. Another week goes by & I turn
up to collect, to find that he hasn't coated mains & conrods.
He says to use the fine powder from the kit on them. I take them
& go home.
Now the final assembly.......
Start with the bottom end.....cleaning cleaning etc. Notice that
all of a sudden there is a big gap in one of the "o" rings
around the block. Brother & I both say we would have noticed
this earlier......I check my pictures and can see that it is a complete
circle, no gaps. So I take it back to machine shop [by now, my car
knows the way there so I just sit back and relax as it will drive
itself !]. I See the bloke running the place, not Boss. He says
it will be fine. [3 mm gap!!!] I ask to see the boss, he says “he
is around corner”, “where I say”.....so off I
go. Boss takes one look starts shaking his head. Turns out that
they farmed this out to some other company & they must have
put a small piece in there to bridge a gap, which we must have dislodged
when cleaning. So they send it back. I gets this back the same day!
[message there some where] However these rings would later cause
Again with the cleaning. Crank & bearings in, bolts tightened
etc. Pistons onto rods........No 1 pin awfully tight, in fact, can’t
get it in! Lots of measuring. Aww-shit! Looks suspiciously like
rod has been damaged on little end aaaaaaaarrrrrgh! So small end
is ever so slightly damaged....what to do. Reaming it out will make
hole bigger all around. So decide to use fine sand paper on end
of round rod to dress high spot. Lots of care here and much checking
produces a very good result.
So back to it.
Rings on, pistons in, head on etc. Set up cam timing to find that
original Cam sprocket key way is spot on. Can’t believe it,
so checks it couple more times. Its ok! Check it the ‘Esslinger’
way to find it’s a couple a degrees different. We mainly tried
it this way to see if their way was credible [later I would set
it this way as it is retarding the timing ever so slightly]. Start
checking the rocker wear areas etc. to find one rocker is touching
retainer, so take this one out and relieve it some more.....much
better now. Put the sump on......wont fit. Must use correct pick
up with sump.
That's about it, took like 3 months
to get this far though!
Some things to consider
If above wasn’t so true it
would be funny.
I have talked to other people who
have had engines built.
They have also had “experiences”
To lessen this I suggest that you
write down what you want done, in detail. Leave one copy with engine
and another with boss. Thoroughly discuss each item with boss so
that he knows what you require. If he is vague about a particular
process or says he will check it out, re-discuss it with him. Communication
between workshop owner and machinist is sometimes vague. Generally
the machinist is very helpful. Talk to him if possible. Set a positive
time frame that both agree with. Keep him to it. Things get lost
or forgotten as things drag out. If any one of the above cannot
be sorted out prior to starting, move on to another workshop.