Hi Guys, Can someone please confirm for me that a Bosch 009 dizzy on a T4 1800 engine with twin carbs should be timed at full advance. That is 3500rpm, and i've found various figures 28-30, 28-32, 27-29 all in a similar range. What would you expect it to be at idle (850-900rpm)? thanks, John
A type 4 shouldn’t have a 009 but maximum advance 32deg if you’re brave and are not bothered about possible engine damage from detonation (pinking). It doesn’t really matter what it is at idle - as long as it will start. You’re compromised by the wrong distributor and you’d be better fitting a SVDA and carefully placing the 009 where it belongs. Somebody
I'd stick to 30 max whichever type of distributor. They usually end up around 10 degs at idle, but as 77 Westy says, the idle figure is irrelevant, the engine won't be damaged at idle speeds.
Thanks for that. I had to remove the dizzy (dropped a screw in when fitting new points!) marked it and retimed the engine but am not happy that it is running well enough yet hence checking. It has run ok on the 009, Germany last year, but wore out a pair of points in doing so. I'm getting a bit fed up with adjusting points on various vehicles so was thinking of changing. If I kept the 009 as a spare, bought an accuspark vac advance dizzy off Fleabay would you consider that a good move. The carbs are DRLA 36. Am I correct that the vacuum port is the outlet (currently blocked off) just below the stamping DRLA 36s?
Yes - the vacuum port is just below the DRLA 36 stamping. Normally this is connected from the distributor to the left hand carb on a type 4 engine. Ideally you'd also fit an "anti-pulse" valve in the line to stabilise the advance if taking vacuum from the LHS carb only. You can just see the the vacuum connection with anti-pulse valve (the brass thing halfway along) in this photo:
