I have some questions about 'Speed timing' my 1275 engine in my bugeye.
First of all here's ,my setup.
Freshly 'rebuit' 1275
- .020 over piston
- Kent md266 cam/springs/lifters set. (timed in at 7degrees from TDC)
- 12g940 head (mildly ported, and port matched to manifolds) w/K&N filter
- dellorto DHLA 40 (simular to weber DCOE)
- Maniflow LCB for 1275
- 1.75 exhaust system
- Ignitor electronic ig in stock Distributor ('71 1275)
When I timed the engine by ear, my timing setting ended up being between
18-21Deg at 1000RPM, with smooth idle, and plenty of power between 2-4000RPM.
I then speed timed the engine at ~4000RPM and the setting from above showed it
was running 40+ degrees at full advance.
I then reset the timing to ~30 degrees at full advance.
Now I have a much rougher idle, and It seems like my power band shifted to
between 3500-6000 RPM. The timing mark at 1000rpm with the vacuum advance
disconnected, is now at about 6 deg.
I also noticed when speed timing that my timing mark wasn't 'jumping around
randomly, but that I saw two pretty stationary timing marks about 5 deg apart.
The car does start and idles well, although a little rougher than I'd like. I'm
wondering if now I'm running too retarted at low rpm.
Anyone have any experience with this that they'd like to share?
Please remember this is a 'street' car, NOT for track.
Also, even though my plugs look good after 2-tanks of gas, (nice tan deposits),
I'm getting less than 18MPG! this sounds way too low for a car/engine of this
size. Not to mention the fact that this is with a 5-speed OD 210 tranny.
Regards - Bryan Vandiver
San Jose, CA