Zephyr 4 & 6 Modify And Rebuild Tips
(Special thanks to Graeme White
from Enford, Phone 03 379 3775 or E mail: mail@enford.co.nz for part swapping/fitment details).
These are some tips for Zephyr, Zodiac and Consul owners
doing an engine rebuild.
I haven't had a six-cylinder motor in any of my Zephyrs in
ten years or more so I had to remember a bit.
I've written what worked for me on several motors that were
reliable and fun to drive. Clubs always have members who are willing to help
and will be able to offer more than this. Enford at Phone 03 379
3775 or E mail: mail@enford.co.nz supply
parts for these motors and others, find their catalogue in the index of this
site.
Follow tips for any good engine rebuild eg: safety, plan,
cleanness and crack testing. Get machining work done by a good engine shop that
does older and/or performance work as they know what to look for and they'll
have better contacts for new parts.
The Mk 3 Zephyr 4 had the bigger ports of the Mk 3
six-cylinder
engine, but the narrower bolt spacing of the Mk 2 engines, which also had
smaller ports.
Start off with a Mklll cylinder head (best ports and valves) this has 213E
embossed on it. You will find this number under the thermostat housing as
well as topside between the rocker cover and exhaust port.
Contrary to popular belief, the Mklll Zodiac head is not
different than the usual fitted MKlll Zephyr high compression head but some
countries were sent export Zephyrs with low compression heads fitted and in
that case accompanying Zodiacs were always still fitted with high compression
heads unless changed at the dealership. This is when the 2 models would have
had different heads, but again, only in compression. The heads are stamped on a
machined pad above the intake ports with an H for high compression and an L for
low compression. Visually the MKlll low compression head looks similar to a
MKll head when viewed along the manifold mounting top face. The low compression
head is rare.
Do get the head crack tested and or pressure tested.
You may want to look into getting lead free seats installed at this time. I
would recommend a shop that deals in porting and performance work with a flow
bench to modify the head, Match the exhaust and intake ports to their manifolds
and polish the combustion chambers. Do leave a rough not polished finish in the
intake port. Blend the valve seats as they enter the port on both intake and
exhaust and try not to lower the exhaust port floor. Watch for water jackets
when porting! All porting etc should be done before final valve seat work. For
loose valves have new guides installed or ford V8 302w valves, which have
thicker stems. Mklll valves are already of a good size as they stand, larger
valves can further shroud the combustion chamber, cutting airflow unless the
combustion chamber is back-cut to match the inside perimeter of the head gasket
to add flow back. Available new now, are valves with oversize stems. Sixty thou
can be planed off the head to raise compression, however a light skim is enough
to get a good gasket surface. Be careful to look at the underside of the head
to gauge the amount already taken off by seeing how close the lower exhaust
bolt hole is to the machined surface, less than 3 mm thickness here and you
would be best to get a light skim only. Get a reputable shop to plane the head
carefully as some shops will take the whole lot off in one go with the wrong
machine, which heats the head and leaves a wavy surface. Rocker shafts can wear
badly but like the rockers themselves, these can be built-up and re-worked and
the rocker shaft cleaned out. Check for the oil feed pipe fit into the oil
supply tube inside the side plate. We have a page on site on the installation
of lead free seats in the left hand side bar, thanks to Havard in Norway.
Pick a Mklll block 213E coded, these have valve reliefs cut
into the deck of the block. The blocks are cast with a T followed by a number
indicating the thickness of the bores eg: T4 will bore out further than T1.
When you have the motor mocked up, check valve clearance in the valve reliefs,
as these might need enlarged/deepened for different valves or different cams
etc. Do not cut too deep down to the top piston ring area. Mkll or lll cranks
interchange. Allow for 0.090" intake and 0.120" exhaust, valve to
piston clearance. I've had to get a block align honed before so that the crank would
spin freely. Mklll connecting rods are the strongest to use.
Use a MK ll or lll cast iron oil pump instead of the later
high wear (alloy) Mklll oil pump. Skim flat its end plate. Pack the pressure
relief spring with a 2mm spacer to boost oil PSI. Match the oil hole in the
pump to the feedhole in the block as well.
Peter Lukeis passes this tip onto us, ‘Some rare Mklll
Blocks from the factory had the main bearing tunnels bored .015 oversize, this
was to correct poor main bearing tunnel alignment‘, (something I have myself
found in used Mklll blocks-Karl) this can be a costly thing to find out at the
end of a build so to confirm you don’t have one of these rare blocks check the
following two notes of interest:
“OS” will be stamped on the block face that meets the sump.
The original main bearing insert part numbers will end in a
“G”
Adding to information on blocks, I myself have noticed a
number of Mklll blocks which have cast in “ribs” standing proud on the
starter motor side of the 6 cylinder block and inline with that sides
frost plugs.
I know some early Ford performance blocks were noted for
outside ribs but whether the same stands true for this Mklll block I doubt. I
do however believe these blocks may be cast at a different foundry.
New pistons are available now and you can use others eg:
(involves machining) Bedford, Valiant, Holden or original pistons in a sleeved
block. Early ford pistons have narrow top ring grooves that can be opened up to
fit a new thicker ring or they can have a spacer added, this work should be
done after crack testing. Some people years ago used to leave the lower ring
out of the 4 ring oversize pistons for less drag. I myself prefer the extra oil
control and piston support with leaving that ring in place. Over-size pistons
are now available new.
If you are not replacing the cam keep pushrods and lifters
in order with camshaft lobes 1-12 as they wear together. Original lifters and
camshaft can be reground, I find the stage two grind (262adv-duration) is a
very good all-rounder. Stage three (290adv-duration) is not very good for
street use or for MPG but is a good open road cam. I get my camshafts ground
through Kelford Camtech (www.kelford.co.nz),
they can supply a cam for your needs depending on the cars intended use. I can
supply grind Spec’s if you have cam grinders near you in your area. They can
also tell you whether you can get by with standard new springs as well.
Standard valve springs new from Enford or other stockists, will support
6500-7000rpm with a stage 3 cam, going from my own experience with standard
rocker gear. Some MG cars share the same timing chain, also available new
through Enford. As well as Mk 3 Zephyr 4, timing chain tensioners were also fitted
to late Mk 1 and all Mk 2 Consuls, these timing covers can be fitted to 6
cylinder engines if desired. Mk 1-2-3 timing covers are all interchangeable.
Intakes
In our FAQ/Part suppliers section are aftermarket intake
manifold suppliers. Plus we have a DIY two barrel intake article on site.
A Mklll Zodiac carb {42WIA-2} and manifold {213E-9425-B}
are a good all-rounder. The zephyr motor being under carbed from the factory
(The Zodiac carb is also jetted richer than the 3.3 Cresta!).
Zodiac
Mklll
Carb
Zephyr Mklll Carb.
Port match to the head the intake you use but do not
polish the inside surface. Alloy welding a two-barrel adaptor to a standard
manifold (and opening up the inside plenum) works well. Manifolds were made by
Aquaplane, Berry & Chung (B&C) and Griffiths,Sheppard Bros as well
as others. Keep an eye out at swap meets etc. I would recommend a twin barrel
downdraft Weber over triple side drafts as far as tuning and maintenance goes,
however, triples may offer a slight edge at the top end of the rev range. To
set either of these carburettor systems up, I would strongly recommend a
rolling road Dyno.
SU carbs:
Below are baseline settings for 2 triple SU carb set
ups (different throat sizes) plus 1 twin SU set up, these are for a
Mklll engine with a mild (stage 2) cam.
3 x 1 1/2, needle 3 , spring
Red
3 x 1 1/4, needle ES, spring Red
2 x 1 1/2, needle 7 , spring
Yellow
Also I strongly recommend an inline regulator for SU's plus
good air cleaners. I found the standard Mklll fuel pump could keep up with SU's.
Make sure the type of oil and its grade is at the same
level in each dash pot for that model SU. I set a fresh SU carb
set up by inserting a rod long enough to stop the butterfly from
closing, into the throat of each SU (lift the slide to do this) and adjust the
butterfly, by its linkage, to gently rest onto this same rod for each
carb, this gets the 3 or 2 SU's set for equal throttle opening. Then retighten
the linkage. I use to have a favorite long thin screw driver just for
this!
Once the car is running use a 500mm or longer piece of 25mm
fuel or heater hose to listen into the mouth of each carb, with the air cleaner
removed, and listen to the pitch of the whistle of air going in so you can
equally adjust and set each carb to the same pitch to get the carbs in
balance. This also works for some multi downdraught carb set ups. Afterwards
install good quality matching air cleaners.
I would then again suggest further tuning on a Rolling road
for best results.
Aftermarket intake adapting:
Member Syd Handisides has mentioned how close the GM Holden
Red six intakes are to the port spacing on our Mklll engines, this opens up the
range of more multi carb and two and four barrel aftermarket intakes for our
engines. Alloy welding and cutting to the flanges would need done where
the intake mets the head and this is certainally possible as I have had intakes
made at a fair price before for my hot sixes.
Holley and other 2 and 4 barrel carbs:
A small 465 or 450 cfm Holley as used on small four
and six cylinder engines from the Holley range would be easy to get, their
450cfm Holleys for V8 tunnel rams are actually very well priced too. Holleys
are available rebuilt as well at a cheaper price.They are very easy to tune
as well.
I have also looked at the small Nikki 4 barrel carbs on
Mazda Rotory engines ( 12A) as they are nicely sized and the Mazda intake could
be sectioned to go on the Mklll intake to be welded together as one.
I prefer carbs with mechanical accelerator pumps over SU
type cars myself, I found they responded better on the hotter Zephyr
engines.This may be down to hotter cams giving less of a vacuum signal to a
vaccum operated carb.
Weber carbs:
The Weber carb (40 DFA-1 or 38 DGAS ) off the 3 litre
MklV Z car or V6 Capri is a very nice running carb on a mild engine if the
intake is remade as in our sites Two barrel article, the stock jetting is very
close too.I have also run the 28/36 universal Weber as well however this model
is getting harder to find.
The standard hockey stick tube manifold is very restrictive
making extractors a must, at the very least a zodiac twin manifold all leading
to a 2.5 inch pipe with a V8 car type muffler. Pin D plates after port matching
them if they keep moving out. The D plates are half cylinder alloy (or brass)
inserts that pack the exhaust port out pass the heads face, these can be made
from scratch if you can’t buy them. The tubing from the ports should be as
large as (or slightly larger for an anti-reversion effect) than the port size
itself or exhaust valve. Then get the headers made up by any good exhaust shop.
A search on the net located companies that had D-Plates and headers for Zephyrs
etc. Contact Endford above or sales@Autobend.co.nz
in New Zealand or try local outlets in your area/country.
Mk 3 used the same ignition for 4 and 6 cylinder. Mk 1 and
2 four cylinder used different distributors to Mk 1 and 2 six cylinder. Get the
distributor recurved by a performance tuning shop. If you're running a stage
three (or higher) cam the vacuum advance will be redundant. A multi spark
(MSD-5 or MSD-6) or an Transistor Assisted Contact (TAC) ignition box can be
used by using the points as a simple switch, or go to a full electronic system.
Do make sure you have the matching coil. You can get by with a well set up
single points distributor and performance coil however. Your original timing
marks will differ now with modifications, so once again I would recommend a
Dyno tune when doing the carburation as well.
NOTE: The sound of a worked Zephyr is hard to beat. They
also are very rewarding at responding to modification and this does not seem to
impend reliability. I would also recommend on a high compression motor, running
a MKl or 3.3 Vauxhall Cresta starter motor (enlarge the pinion hole in the bell
housing) and also fitting an alternator which is more reliable at charging and
can handle high revs easier. A Lucus Alternator with in built regulator marked
17ACR or higher is an easy wire in. Again, these modifications are from my own
experience and are only a guide to give you ideas and are solely my opinion.
Do make sure all work is carried out in a safe manner and
when necessary all work should be carried out by a qualified mechanic etc.
Disclaimer:
The advice and guidelines given in these articles are given in good faith.
The owners and managers of the Galeforce Zephyr site will take no
responsibility for any injuries or loss sustained while carrying out the
described tasks and procedures or any consequences arising. Please read
the Safety First
Article