simple guide to Bosch conversion

[philrylance]

For those readers like me who have a lot of interest but not a lot of experience or engineering know-how, I have put down here a simple method of fitting a Bosch pump to a 1972 CP TR6. The pump number is 0580 254 996. I bought it from John Sykes of TR Bitz at Stoneleigh and also got a fitting kit which comprised two short lengths of rubber petrol pipe, two galvanised unions and four crimpers. TR Bitz sent me the new appropriate filter in the post, as the old filter does not have holes in the bottom which makes for a better flow I am told.

 

This is what I did!

REMOVE ELECTRICAL CONNECTIONS FROM LUCAS PUMP –

REMOVE BATTERY LUGS IF YOU WANT TO BE SENSIBLE!

 

1. Clamp the pipe from tank to filter.

2. remove old filter catching residue petrol in a bowl – app.2 cupsful.

3. remove in and out pipes from Lucas pump

4. remove pump from car – socket used under wheelarch and open ender for the rubber lug end in the boot.

5. fit new unions to new rubber pipes( one each)– the small bore pipe is a little difficult. I clamped them with small jubilee clips ( crimpers didn’t work for me)– the outlet is v. high pressure - it needs a clamp or clip!

6. Fit new pipes to Bosch pump – LARGE to the top of pump( inlet) – SMALL to the bottom(outlet) – Jubilee clips once again.

7. Now join the new unions to the existing pipework unions from the filter( large pipe) and to the PRV( small pipe). YOU DO NOT HAVE TO REMOVE ANY EXISTING PIPEWORK FROM THE LUCAS SYSTEM.

8. fit the new filter and remove clamp.

9. fit the pump where you wish – I used the bottom 2 lugs of the lucas holes on the inner rear wheelarch. – no drilling ! People talk of the lower the better because of gravity feed for the Bosch from the tank but mine seems to work well. However I will try it in the bottom of the spare wheel well soon.

10. I lengthened the elec. leads to the pump and fitted lucar(spade type) connectors to match the Bosch pump. Lucas use bullet connectors.

11. I held my breath, connected all the electrics, switched on and waited a few seconds then fired up. The car started on all six and has run superbly for a few hundred miles at the time of writing. It stars superbly well in the mornings and also when warm.

12. For the purist I didn’t fit a relay, or a pre filter and didn’t check yet with a pressure tester( which I will do soon). I used all existing cables for power supply

The whole job took about four hours but that included thinking time( very slow for me). I mistakenly thought I had to remove old pipework before two calls to TRBItz sorted me out. I think to do another would take about two hours.

 

I am not trying here to decry expert advice, but some readers will appreciate that like myself they may be confused by technical engineering speak. I am very proud that I did it myself as my ability is limited, being a retired guitar-playing teacher. I am willing to accept any comments, help, advice from wherever, but remember that you cannot belittle my achievements as they are already as belittled as they could possibly be!

Phil Rylance

 

 

I will try to enclose is a very simple diagram of what I did.

[jonlar]

Well done Phil, the relay isn't there for the purist or even pedantic concours buff, a relay gives the pump (Lucas or Bosch) a fighting chance of getting full voltage, or at least as high a voltage as possible. A heavy gauge cable has to be installed to supply the pump through the realy, using the original wiring to switch the relay. This helps prevents voltage drop.

Edited February 28, 2006 by jonlar

[scotty]

Well done , when I changed mine I also changed the union at the base of the fuel tank to a larger one - just a screw change really - this allows more fuel to get to the pump .

[Smeggie]

Brilliant

Its nice to see a simple solution which has been really well executed and described. It sounds like youve got it sorted. For info I have just added a relay to my TR using a supply from the alternator and the tone of the pump now remains constant under all conditions, which it didnt before. To be honest at the moment Im using the original wiring loom for the pump and will change this latter. The best thing I think is a more direct supply to the pump which means the ignition switch and and hidden pump isolator switch now only operate the relay and so dont carry any current as such. If you would like a kit to measure the pressure and then monitor any further mods you might make such as repostioning the pump or adding a post pump filter (seems wise to protect the metering unit) or changing the outlet from the tank etc, I can make you a kit starting at £39.99 depending on which gauge you fancy. I have an example on the Trade forum

So not wishing to muddy the water I was led to believe that these bosch pumps had a problem sucking and required a bosch type free flow filter can any one correct me on this or is the standard Lucus filter ok assuming you can connect to it.

And not wishing to pry roughly how much did it cost for all the bits?

It still sounds a great solution to me

 

So enough rambling

Happy motoring everyone

Cheers

Smeggie

[Richard Crawley]

Well done Phil, glad it worked out OK. I may yet go the Bosch route later this year if my other ideas don’t cure the persistent problems with evaporation/cavitation I have been experiencing since the rebuild 2 years ago.

 

Unless I have misunderstood, the hoses in your kit were not supplied with the unions pre-fitted. The low pressure side should be OK but I am a little surprised this is the case with the high pressure outlet hose; can others advise if this is normal with these kits as I would consider this a safety issue?

 

Some years ago I was preparing my boat for a river licence safety inspection by the Thames River Authority & was surprised to learn that they did not allow the use of Jubilee clips on either the gas or fuel system hoses & I had to change the lot to crimped fittings! One of their safety engineers explained that the problem with Jubilee clips is the clamping force can vary enormously depending on how tight they are done up (& most people tend to over tighten them!), whereas the crimped type will always provide the correct & consistent clamping force given the right size crimp/hose combination is used. He also added that vibration can cause the rubber hose to fail without warning at the clip as they tend to restrict flexibility, particularly when over tightened. Now I would normally have been sceptical of this comment but I had previously experienced such a failure on the fuel supply hose to my boat engine on an installation that was no was more than 2 years old. To my horror I found myself with fuel everywhere, without power & fast drifting towards a mass of pier supports in the very strong tidal currents that exist on the Thames in London. I had no option but to let go the anchor & pray it held first time; luckily for all of us it did but I had a hell of a job trying to get it up again! I still use Jubilee clips but err on the side of caution & always consider the consequences of failure!

[rob wilsher]

I've read several threads about the pump relay mod and it seems to be a popular addition. Wasn't the original electrical specification/equipment adequate without it or is it only really required when fitting a bosche pump set up?

 

My 75 TR6 has the bosche conversion without the relay. What will I gain by fitting one?

I am intending to move the pump/filter etc out of the boot because of the petrol pong. (I've replaced the fuel guage sender gasket, tightened the connectors, and found no leaks)

 

Any advice regarding this conversion would be helpful.

 

Thanks

 

Rob

[philrylance]

Thanks to all for the constructive comments. I feel like a real engineer! My Dad was a a fitter and turner in Thanks all very much for the constructive comments. I feel like a real engineer!! My Dad worked in Crewe locomotive works for LMR for 46 years as skilled man! I play guitar and bridge - badly!

 

Richard - I couldn't agree more, the fixing of the hoses to unions is very hit and miss when you consider the medium involved and the possible consequences. I did my best but without proper tools or the original style reinforced connections what can one do? I do not understand crimpers!!! I have the scars to prove it.

 

Jonlar - I agree with your sound common sense but I have no knowledge of relays, what they are, or what they do. Any help would be more than welcome.

 

Scotty - was it difficult to enlarge the outlet from the tank?

I have visions of petrol all over the drive and the fire brigade in attendance.

 

Smeggie - cost - Pump - £150 I think a show special from the suppliers TR Bitz - they gave me the pipes etc. and supplied the filter free via postage. John Sykes was excellent on the day at Stoneleigh with helpful advice, and his firm was more than helpful on the phone, in the boot, cold and damp, fed up and tearful, there when help was needed. I paid total £150 but reckon to buy after the show would be a little more expensive.

 

Any more comments would be very welcome.

 

Cheers and thanks

[scotty]

Phil , the outlet that the pipe between the tank & pump screws onto will in turn unscrew from the tank. I got one with a larger bore from Malcolm at Prestige Injection . It just screws into the tank in place of the original - real easy BUT make sure the tank is empty first or your visions may come true!

[jonlar]

Hi Phil,

 

a relay is an electrically operated switch, I've made up 10 - 12 (@ 12.50 + post at cost) for Forum members ,with all complimetary comments. The switching is achieved by a very low current solenoid coil (basic electro magnet) which when energised either truns the electric on or off. The relay is supplied with a fused supply direct from battery or similar +ve supply, just using the OE wiring (which is really too light - low current - especially for a Bosch fuel pump) to switch the relay, this avoids high resistance which occurs in corroded/tarnished terminals and especially the Inertia Switch, which can overheat and melt.

 

To fit one is extremely easy. I use 50A red cable with 60A relay (I can do a double pole if you would prefer, or need another ignition switched supply in boot. I crimp and solder on the connector side of the terminals, you will have to cut cables to length (I allow at least a metre spare on the +ve) and crimp/solder connectors (which I send) on yourself, it's easier to get the cable through without terminals. I also send a 50A black earth lead, F/P to chassis or body (personally, I prefer the chassis, but you can carry the earth through to body instead or as well). Drop me your postal address by PM or email.

 

I think Revs and Moss charge in the region of 30 pounds for a kit, but don't know what rating cable and relay they use.

[scotty]

I can vouch for Jons kit , he kindly made one for me , straight forward instructions and I fitted in about an hour .

[BryanD]

I fully agree with the benefits of a relay (a tenner very well spent) but to go back to the original topic:

 

The diagram shows the filter before the pump. The Bosch ones are normally fitted after it in the line. This seems a bit illogical to me, but apparently that's the way they are...

 

My car is set up as per your diagram with the original filter case, but I was warned by Richard at TRGB that this may restrict flow - even though the pressure was Ok at 1-6 PSI.

 

I mean to replace it with a Bosch filter at some point, but you don't seem to be able to buy them on their own.

[saffrontr]

Well done Phil,

My Bosch pump is plumbed in exactly like yours, still using the old CAV filter and even mounted in the same place as the old Lucas pump. I don't have the enlarged outlet nor the uprated wiring system and relay (although this does sound like a good idea). Fitted 21 years ago back in 1985 and still hasn't missed a beat and I don't hold back on the right foot either.

Derek

[davidc]

Hi Phil:

 

My set-up is exactly as in your diagram and, like Derek's, dates back to the mid 80s. When I queried the use of the original Lucas filter one specialist told me it wouldn't work and a second said "If it ain't broke, don't fix it". Well, it ain't broke and works well.

 

I did make one change when I bought the car two years ago. The pipe from the filter to the pump was green plastic garden hose! I replaced it!

 

David