078 Distributor for B20B

swedishandgerman · Aug 9th, 2010, 09:06

I have an 078 distributor for a B20B that I'd be interested in swopping for a good 077 distributor for a B20A

Alternatively, as soon as I've found a good 077 distributor (must be good), mine's for sale!

Derek UK · Aug 9th, 2010, 11:59

What do you think the differences are between the 77 and 78?
B20 Amazon parts book lists 0 231 146 077 for B20A and 0 231 146 099 for B20B.
Yes. the book shows some differences including springs and the vac unit.
73 on 140 book shows different part numbers for B20A and B but no Bosch numbers unfortunately.
What engine are you trying to match up with the dizzy, the '75 145 one?

swedishandgerman · Aug 9th, 2010, 13:29

Hi Derek

The 078 is a vacuum retard and the 077 has vacuum advance. I haven't seen a 099 distributor before - I thought all B20B's had 078's and all B20A's had 077's (on 140's as well).

It's more of an experiment thing that I'm looking to change for - that's all. It's just a stupid geek thing that I like doing, looking at different distributors. Sad, isn't it?!

I just remember that the 078 distributor was used in some late Beetles to reduce emmisions - the point of the retard was so that the mech advance allows the timing to be advanced with closed throttle to reduce hydrocarbons on closed throttle, high rpm so improve burning the unburnt gases in the chambers. When you opne the throttle, the vac advance pulls the timing back a bit to stop pinking

I prefer the simple principle of a vac advance system

Yes, the motor's out of an L-reg 145

Aug 9th, 2010, 09:06	#1
swedishandgerman Premier Member Last Online: Oct 23rd, 2023 21:39 Join Date: Apr 2007 Location: EXETER	078 Distributor for B20B I have an 078 distributor for a B20B that I'd be interested in swopping for a good 077 distributor for a B20A Alternatively, as soon as I've found a good 077 distributor (must be good), mine's for sale!

Aug 9th, 2010, 13:29	#3
swedishandgerman Premier Member Last Online: Oct 23rd, 2023 21:39 Join Date: Apr 2007 Location: EXETER	Hi Derek The 078 is a vacuum retard and the 077 has vacuum advance. I haven't seen a 099 distributor before - I thought all B20B's had 078's and all B20A's had 077's (on 140's as well). It's more of an experiment thing that I'm looking to change for - that's all. It's just a stupid geek thing that I like doing, looking at different distributors. Sad, isn't it?! I just remember that the 078 distributor was used in some late Beetles to reduce emmisions - the point of the retard was so that the mech advance allows the timing to be advanced with closed throttle to reduce hydrocarbons on closed throttle, high rpm so improve burning the unburnt gases in the chambers. When you opne the throttle, the vac advance pulls the timing back a bit to stop pinking I prefer the simple principle of a vac advance system Yes, the motor's out of an L-reg 145 Last edited by swedishandgerman; Aug 9th, 2010 at 15:05.

Aug 9th, 2010, 11:59	#2
Derek UK VOC Member Last Online: Today 15:54 Join Date: Jul 2006 Location: Chatham	What do you think the differences are between the 77 and 78? B20 Amazon parts book lists 0 231 146 077 for B20A and 0 231 146 099 for B20B. Yes. the book shows some differences including springs and the vac unit. 73 on 140 book shows different part numbers for B20A and B but no Bosch numbers unfortunately. What engine are you trying to match up with the dizzy, the '75 145 one?

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