1990 Mini Racing Green (now orange, blame previous owner)
Engine Specs:
1293 A+
Swiftune heritage pistons
Big valve head
3.1 diff
standard rockers
MED ST1 lightened flywheel
LCB + RC40 DTM twin box exhaust
Alloy intake (standard from Minisport)
HIF44 w/ BDL needle, 20w SU oil in dashpot, Red spring
Gold coil (1.48v across coil, 11.68v positive coil post)
electric fuel pump
filter king regulator/filter
Running with 93 octane fuel (American MON) = ~98 octane (UK RON)
I have been told that my timing should be happy ~10-12* btdc. The issue is when I have set it this low, I encounter bogging, backfiring in mid throttle, and overall terrible throttle response for anything above idle. I've used a colortune to set the idle mixture, as well as tested the rev band with it and everything appears to look correct. I've toyed with the timing up to 15* btdc and it responds much better, to the point that I'm able to drive on the highway at wide-open-throttle and have hit ~93mph (I live in Texas, we have fast highways ) but it still has some hesitation in 1/2-2/3 throttle. I'll break it down in detail below...
- 1k idle @ 12* btdc (set with vacuum disconnected and plugged)
- 1.5k @ 16* btdc (read with vacuum disconnected and plugged)
- 2k @ 20* btdc (read with vacuum disconnected and plugged)
- 3k @ 24* btdc (read with vacuum disconnected and plugged)
- Mixture is bunsun blue at idle, half/half when revving to ~2k, yellow when snapping to open throttle
- 1/4-what engine bogs down/poor throttle response, eventually backfires, cannot achieve speed greater than ~45mph
- 1k idle @ 15* btdc (set with vacuum disconnected and plugged)
- Mixture is bunsun blue at idle, half/half when revving to ~2k, yellow when snapping to open throttle
- Good idle, decent acceleration up to 2/3-3/4 throttle where it slightly hesitates/some loss of performance occurs, then wide open throttle it wakes up and takes off
If 15* btdc @ 1k rpm idle is considered, normal, then I'll start toying with needles.
If the common agreement is that I should be trying for 12* btdc, how?
Edited by Omnomsan, 14 October 2021 - 09:34 PM.