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Fuel pump spacer ?


William_Lake25
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Hi all.

 

I am in the process of restoring a Triumph Herald 13/60 and have come to a halt at the fuel pump... The original fuel pump wouldn't pump.. Instead of replacing the valves and diaphragm, we purchased a new fuel pump that is supposed to fit a herald 13/60... However, the arm on the new pump is too long, I've heard that a spacer would solve this issue, and I am inclined to believe that... The issue I'm now having, is that the studs which secure the fuel pump to the block, are too short. My question I, whether a spacer would solve this, or if the arm is actually the wrong shape, therefore a spacer wouldn't help ?

 

Thanks.

Will.

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There are effectively two types of fuel pump - those with short arms and those with long arms.

The long arms stick out much further than the short arms.

 

The short arm ones will physically fit with a spacer, but then the arm is too far away from the lobe on the cam to operate properly.

 

The long arm ones normally will not fit unless a spacer is used - if you do manage to fit one without a spacer, and then run the engine the lobe on the cam will apply too much pressure on the arm and it will break the arm off.

 

So long arm pumps are used with a spacer, and short arm pumps are used without a spacer.

The studs need to be longer when using a spacer.

 

The advantage of using a long arm pump (with a spacer) is that the spacer thermally insulates the pump from the engine block, which reduces the heat transfer from the block to the pump and onwards into the fuel, so the fuel arriving at the carbs is slightly cooler, which in turn makes the engine very slightly more efficient.

 

I use short arm pumps as I have old rebuildable ones that I only have to recondition with a repair kit every few years.

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Will,

The only pump that should need the spacer is the one for the late Spitfire 1500, TKC3417.

I would suggest you have suffered from the all to prevalent " one size fits all" attitude to spares found with a lot of suppliers of parts for our cars. The part number you should have is 208493, this should have screw on connections for both inlet and outlet.

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you should have a  short arm pump     208493,,  if this is what you have and its a long arm then supply is incorrect to  part number.

the longer arm        tkc3417 was used on  late 1500 with the spacer ukc8523    late spit IV and early  dolly/spit 1500 used rkc1624 without spacer 

 

some evolved changes were push on pipe fittings   well something like that !!

 

yes if using the spacer you need longer studs , a setscrew can be used but needs the threads sealing to prevent sump oil leakage and a stud gives better location.

 

pete

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