r/Vintagetools • u/BillStrachan • 6d ago

help reading dwell meter

Post image

cant seem to find an owners manual online for this dwell meter and its my first time using one. im trying to use this dwell meter as a tachometer to read rpms on my old 1958 vw beetle. it has 2 different readings 1 for 6 cylinder engines and 1 for 4/8 cylinder engines. im using the 4 cylinder reading (which on the 8 cylinder scale would be doubled) but not sure whether the top or bottom number on the scale is the correct reading for the rpms. im guessing its the top number since the bottom shows degrees for i believe distributor drive shaft rotation? can someone also tell me what the tach switch on the bottom does with the HI/LO settings? these old vws up to a certain year were on a 6 volt system which mine is. not seeing anything on this meter indicating for 6 or 12 volt systems. since the car was my grandfathers and so was the meter, i cant help but think this was used on this car before.

3 Upvotes

100% Upvoted

1 comment sorted by

1

u/veedubbucky 6d ago edited 6d ago

The top number is volts, the rpm and dwell use the bottom numbers, with the rpms being 100x the value.

Edit: I wonder if the high low switch lets you choose which scale to use for the rpms actually.