The Editor's fizzing…

Q I took 9600 HP out recently for a long overdue run and there was what I would describe as a fizzing noise coming constantly from the rear of the car. My guess is that it is the fuel pump. Am I likely to be correct? Is it caused by lack of use and will it cure itself with use or will it just pack up? The car is fitted with an original submerged fuel pump. PP

A The first thing is to prove that the noise is coming from the fuel pump, by removing the boot floor and disconnecting the power feed to the pump. If the noise is definitely coming from the pump and is excessive, it would suggest that the pump may need attention. It is possible that the fizzing may be coming from the pressure relief valve, if some debris is stuck to the seat, but there is little else inside the pump to account for the noise.

I would suggest that the pump pressure is checked - it should be2-21/2psi. If it is higher than 21/2psi, the relief valve should be re­adjusted, which will require removing the pump from the fuel tank to gain access to the valve. Apart from cleaning the valve and adjusting the pressure and checking that the pipe connections are not loose, there is nothing more that can be done, as the pump is a sealed unit and replacement is the only option.

Overdriving E-type?

Q    I'm considering fitting an overdrive gearbox to my Sll rebuild project (a manual gearbox car) but I've told it might not be a good idea. Why is this? CR

A It is possible to fit a compact overdrive to an E-type gearbox. The one fitted to an XJ6 4.2 will fit, but will need to be overhauled and uprated to take the power reliably from the E-type engine. The biggest problem is fitting the overdrive gearbox into the car- on an automatic E, the tunnel is larger and will accommodate the overdrive box, but on a manual transmission car the tunnel is too narrow and would require careful modification, not only to provide clearance for the box but, more importantly, to keep the strength of the floorpan, with additional bracing sections welded in after the tunnel has been widened.

This sort of modification should only be done by a specialist, to ensure that the integrity of the bodyshell is not compromised. Since the car would then be non-standard, perhaps one should also consider the alternative of fitting a 5-speed gearbox such as the Borg Warner T5 or Getrag, which will fit without any tunnel modifications. One of the advantages of fitting a 5-speed gearbox is that the car can always be returned to its standard form at a later date if originality becomes an issue.

Series I Not stopping

series I Slow Revver

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