John,
Thanks for the feedback, I have tried to add the info that you requested
below.
On the head front, I seem to be fortunate since the later 72 '6s had the PI
type head (for some strange reason, the US-spec cars from 69-mid 72 had
different port spacing) - the clue to having the "correct" PI type head
being the double downpipe exhaust header. This head also often came with
double springs (but not always on the later years), but that is an easy fix
anyway.
On the cam front, I am a bit limited since I want to use the car in SCCA
autocross (aka sprints), and to keep it competetive, I really don't want to
go into the modified class where it would be up against big money modified
US/Japanese stuff. The late-72 had the later PI spec cam fitted as
standard, so I am setting mine up as a later version PI (only 125 against
150bhp! -
although the measuring systems changed between 1969 and 1973 so the 125DIN
is likely to be nearer 132SAE). So my metering unit and distributor are
being set up for the PI saloon/post 72 TR6 spec.
On the tank front, you "may" be lucky - if you have the smaller capacity
tank (I think it was 9+something Imp Gallons) that was fitted to 73 cars
on, it may already be baffled (in that they used a similar tank for PI/carb
cars, with slightly different pipe layouts). Mine has the slightly larger
tank, but it does have a return pipe installed ... although used for the
closed circuit fuel vapor venting system, so I am hoping that it "might"
have been baffled. However, even those with PI tanks tell me that the key
to the problem is to install a low pressure feeder pump between the tank
and the pump - whether Lucas or Bosch - (any low pressure solid state pump
will work - I've picked up a Sonic for $30US) that will give a 2.5/3.0
lb/sqin feed to either the Lucas or the Bosch higher pressure pump. This
apparently solves the baffle and the low-fuel level problem well. I am
going to to use the Lucas pump since mine tests well, but like you, I am
going to run it through a Lucas relay mounted by the inertia switch in the
engine compartment, so it will get the the extra juice (also recommended by
everyone for both pumps).
I am intrigued by your mention of the head problem ... not one I've come
across (but that doesn't mean much!). I was aware that some of the heads
have extra "meat" around the valves, and that the racers prefer those spec
heads so they can safely grind out more meat (I've got an email somewhere
that tells you how to recognize these heads, if you're interested). My
head is the 7.75 to 1 head, and I will get it cleaned and skimmed for
"trueness" to about 9.0:1 (and will claim that it was like a banana to any
SCCA type!), and haven't heard of any probs with such a skim (about 0.100"
I think).
I have got some rebuilt injectors from TR Traders in the UK (reasonably
priced too). The metering unit was said to be in good condition, so I'm
going to leave that alone until after it is running. On that front, I have
traded emails with a lot of folks about retrofitting PI systems, and all
those who have had an metering unit and injector rebuild have had a load of
problems ... this may just a coincidence, or it may be a factor of too many
things at one time, so I'm going the slowly-slowly route at this point.
On the metering unit, I did get a lot of emails about the seal materials.
A lot of it was hysterical (frightened rather than funny), and had a lot to
do with the loss of unleaded in the UK (which appears to be more feared
than the loss of the monarchy). Myth 1 - that you need new rotor assembly
because of unleaded. Egil Kvalberg is really the guy to talk to on that
one - he pointed out that the unit is based upon diesel injection
technology, and there ain't a lot of unleaded in diesel fuel. Myth 2: the
seals will crumble in to dust when using U/L. Again, Egil has some good
advice on seal materials - see below
************** clip *****************
Nitrile is the standard all-round good quality material for O-rings. It
is much better than neoprene, for instance. But still not really
chemically stable enough for aromates (i.e. 98-octane).
Viton is the one to go for. It is a comparatively recent material based
on flourcarbones, and is the best there is with regards to chemical
stability. Its main disadvantage, beside cost (which is really pretty
negligible for our purposes), is that it looses elasticity when it gets
cold. Should not be a big problem for our use, I'd say.
Even though Viton is the best there is, the data sheet mentions that it
will not withstand aromates infinitely!
> Did you rush to change your seals
No, of course not ;-)
But remember that when these seals have been subject to gasoline for 20+
years, they are probably ripe for change anyway.
The seals that cause the most trouble are the seals between the injector
inner and outer tubes. When they start to leak, fuel just dribbles out
though that orfice instead of being sprayed in a fine cone through the
injector valve.
> (and if so, where did you get them)?
A standard O-ring house in Oslo. I think they are called something
remotely similar to Shabhan+Buzniak.
Remember to get the Viton type. These are usually light grey in
appearance. The standard O-rings are black.
They are standard imperial sizes. I will try to compile a list of
dimensions at a later date.
> Or
> are you waiting to see
Contrary to the UK, in Norway we've had unleaded only for many years.
The injectors was the main problem, as noted. But it took a couple of
years before it was a problem. The standard O-rings seems to dry out,
become brittle, and loose their elastic properties. Holding the outer
tube, you can easily feel that the inner tube is loose.
These O rings are quite easy to change. Remove the steel spring around
the inner tube circumference near the tip, then, using the end of a piece
of suitably sized copper tube for instance, press the inner tube inwards
and out. Keep on pushing on the inner tube untill it is completely free.
Do not pull on the end of it, since that will cause the valve spring to be
over-stressed.
I've also had problems with the seals around the fuel filter. The
standard seals you get with the original (Rover-something nowadays) filter
is not 98 octane unleaded proof. They started to leak after 1 1/2 years.
When I took the filter apart, the O-ring had expanded in size by 50%!
I've also changed the seals in the metering unit, more as a matter of
course when I took it apart.
The lip seal around the injector pump axle will only last for abour 5
years, BTW.
Egil
************************ clip ********************
I really appreciate your mention of the heater return - darn it, I didn't
even notice that it was different! Luckily, the fix is easy ... a threaded
blanking plug on the housing, and a stopped hose that used to feed the
manifold.
But I still haven't solved the throttle linkage problem ... let me know how
you get your's working - I may be able to adapt your design!
Cheers
Tony Gordon
At 12:30 PM 8/10/99 +1000, you wrote:
>Tony
>
>I don't have a linkage, so I'll get that out of the road. However, I am
>doing exactly what you are doing i.e. converting and ex-US 72 carb TR6 to
>PI. I'm in the process of gathering bits 'n pieces right now. Not sure of
>what advice you have received from fellow listers but would be interested
>in knowing. If you don't mind sending any emails on the topic then I would
>appreciate it.
>
>I have sourced an ex-PI head locally and it is currently being refurbished.
> I'm told it is important to maintain the correct head thickness because of
>problems associated with higher compressions. Double valve springs are
>standard in the PI head and I am told they are goo for over 7000 rpm.
>
>I am getting my injectors refurbished. Also I am getting the distribution
>unit refurbed which will include putting TR5 springs in it. I have got a
>31/71 cam from Wade which is about S2 spec. I will be getting my
>distributor recurved.
>
>When i get a wire run for the fuel pump I am going to get a relay put in.
>This will prepare me for a Bosch replacement pump some time in the future.
>I'm told that it is essential to baffle the fuel tank but this may be a
>later job for me.
>
>I'm also scrounging up other bits such as a PI heater water return rail to
>the water pump, thermostat blanking plug, air cleaner radiator mounting
>braket, elephant tubing and air cleaner mounting stay.
>
>One area that I have to do a fair bit of work on is the throttle linkages.
>I'll have to build a complete new one but the good thing is that it is RHD
>and I can use a cable.
>
>Regards
>
>John
|