I then wondered whether curved pipes were fitted earlier when the servo was factory fitted, not mentioned in the documentation until they became standard in 1972. I googled for images of the engine compartment, did find one that showed straight pipes with the servo, but that was described as a 66 model so obviously modified. Clausager only shows straight pipes with no servo, or curved pipes with the servo. a year after the cans changed, but it had been optional from Feb 1970. It did occur to me that the straight one at the rear could foul the remote servo, and that didn't become standard until 1974 i.e. There is also the question of why the inlet tubes changed from straight to curved anyway. BHH 546 front and BHH 546 rear when they changed to HIF carbs, and stayed that way until the end of production. I can't see any difference between the front and rear cans on my 73.įor 1974 the UK changed to the non-North American export cans i.e. All these cans also changed from straight to curved inlet tubes. How these differed from other export cans is not known. As the only part of the filter assembly that touches the carbs is the alloy base, North America also changed for the 1972 model year and HIF carbs - but to BHH 665 front and BHH 666 rear. For 1972 export models other than North America the can changed to BHH 546 front and BHH 547 rear, which was the same time that the twin carbs changed to the HIF type on those models. Clausager states "to comply with new noise regulations, similar to those found on non-North American models from car number 258001".
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That would have meant an open port on the front cleaner which would be unusual, although not out of the question as it was on the dirty side of the filter.ĭec 71 UK models changed the cans to BHH 548 and BHH 549, the previously straight air inlet tubes changing to curved. These seem to have continued until chassis number 258001 - which was the start of the 1972 model year in Aug 71 - even though the hose to the front can was replaced by the PCV valve in Feb 64, and that was replaced by carb ventilation on 1969 models. Nevertheless the Parts Catalogue shows the complete cans as being AHH 7354 for the front and BHH 154 for the rear. This meant that front and rear 'cans' differed, although I can only see the base being different, not the main part of the can. 'dirty' side of the filter, which acted as one half of a crude form of crankcase ventilation, the other half being an open tube hanging down from the front tappet chest cover. Initially, on 18G and GA engines without positive crankcase ventilation, there was a hose leading from a port on the rocker cover to the base of the front air cleaner, on the outside i.e.