Lotus Elan and Lotus Elan Plus 2 Forums

Hi all on a grey day in November!

Anybody familiar with the sender used in the plus 2? I believe it screws in to where on the 2 seater the capilliary bulb would fit but is the sender "long nosed" to reach a fair way into the water flow as per the elan's capilliary bulb?

I ask because my car uses an electric guage from a (believe it or not) an early Mk 1 Mini deluxe which is a perfect match for the rest of the instruments. I changed it years ago after two new dual guages leaked the ether filling (at ?50 odd a throw). Using a std matching sender I've always had the temp seemingly under-read and wondered if this might be due to the fact that the sender is only short-nosed and out of the water flow to some extent. I've checked the guage reading by means of temp strips and the reading on it looks pretty accurate when compared to the strips.

I'm using the correct matching voltage stabiliser so don't think this is the problem.

I was maybe thinking along the lines of using the plus 2 sender and seeing if this affects the guage reading or possibly grafting the internals of the plus 2 water temp guage into the one I'm using to retain a uniform look.

Any thoughts?

Secondly- does anybody know for certain if the elans that were unservoed as std were fitted with the smaller 5/8 inch master cylinders or were all equipped with 0.7 inch ones?

Related to this- are my calculations flawed- if a 5/8 cylinder equates to a 50/80ths one and a 0.7 one to 56/80ths does this mean that for a given braking effort the smaller cylinder would require 6/56ths less pressure ie roughly a ninth or is the "step up ratio" calculated differently?.

regards

John

John,
It is a wet, grey and dismal day in the northeast corner of the US as well. The +2 electric water temperature sensor screws into the cylinder head at the rear-most of the two ports in the thermostat area. The electric sender has a tapered pipe thread whereas the capillary bulb will have a BSPP thread so you will probably need a different reducing fitting in the cylinder head. The electric sender is extended a bit so it is well into the water path. I don't know if the standard electric sender will be matched to your gauge, you should test the two together in boiling water to be sure you are showing close to 100 C. Brake pedal force varies inversely with the cross-sectional area of the master cylinder bore for constant line pressure. The 5/8" and 0.7" master cylinders have bore cross-sectional areas of 0.3068 and 0.3848 square inches, respectively. Therefore going from a 0.7 to a 5/8 master will reduce the required braking force by about 20% for the same line pressure. Keep in mind that the pedal travel will also be about 20% greater as you still need to displace the same amount of brake fluid.

Hi John,

All Elans were fitted with 0.7 m/cyl except the Federal ones which were fitted with 7/8 to cope with the extra displacement of the two servos.

Regards
Steve

CBUEB1771 wrote:The +2 electric water temperature sensor screws into the cylinder head at the rear-most of the two ports in the thermostat area.

My Europa sensor is installed this way, but only because in this car, it is easier to mount the heater valve in the front port as the heater hose runs toward the front.

My Elan sensor is screwed into the front port because in this car, it is easier to mount the heater valve in the rear port as the heater hose runs toward the rear.

Is there a reason for installing the sensor in the rear port that I don't know about?

Frank Howard wrote:Is there a reason for installing the sensor in the rear port that I don't know about?

The heater valve on the +2 is integral to the heater unit rather than being mounted on the cylinder head. I specified +2 hoping to avoid confusion. The heater hose for the +2 also runs back to the bulkhead as on the Elan. Not having to deal with the bulk of the heater valve the water outlet and the sender unit could easily be fitted into either the forward or rearward port in the head. My +2 came to me with the sender unit in the rear port and I had assumed that to be standard.