, boost retard/vacuum advance details needed

[jono]

OK. Need anyone that knows the vacuum advance/boost retard canister of the

1985,1986 series One turbo three plug ECU flapper AFM vintage

I had the canister reconditioned with a new diaphragm and after some discussion it came back as a retard only - no vacuum advance :(

The reconditioner has done a few in his twenty years and says the innards did not contain the bits to do two functions, only one.I misheard the gist of the conversation.

 

I also find it hard to believe the unit was any different to the others of the past. Another has been sent insisting that it is, was and must be a two  function can, not two stages - must be vac advance and boost retard.

 

Good reasoning and his experience would suggest a spring would be either side of the diaphragm, or in the mechanism controlling things at the back of the housing could do as required.Has anyone experience with these boost retard/vacuum advance units on the Hitachi distributors? The Australia only model distributor is 22100AA063 and the rest of the world I think is 22100AA093 ( I need to check this last number)

 

[ausubaru92]

What base ignition timing do you set your dizzy to on series 1 turbo motors?  20deg like later series 2 MPFI an turbo motors? Do you set advance with the vac line unplugged like you do with carby motors?

Could it be that the retard only diaphragm starts retarding from 20deg advance at -20in/Hg manifold vacuum, through to 0deg advance at 7psi (guessed figures)

[Steptoe]

Set at 20° BTDC with vac advance crimped off for Series One. Fun to watch dmm on diagnostic wire and timing light on timing marks when then get little man inside tap his hammer on block. The diagnosis wire reading goes from stable 1.7V up in stages to 4.5V and timing suddenly pulls back to 10° and gradually steps back to 20°

In the specs for diaphragm there is a negative vacuum spec...neg vacuum is boost pressure

It will be an eye opener for Mike if next can is same as last...we are going to have to work out how the clever Hitachi made it all work