Hi all,
I can't seem to figure out what I should adjust the timing to on my engine. I
Tried adjusting the engine at idle with the vacuum advance disconnected, but it
runs very poorly at the recommended specification (10 degrees) in the haynes
manual. It really seems to run a lot better up around 20+ degrees. It's hard to
figure out exactly where, because the timing marks on my cam cover only go up
to
10. According to the engine serial number, it was out of a '71 midget, and it
appeared completely stock, and original when it was acquired. I have made the
following mods to the engine which may have some affect:
- 12g940 (ported) non smog head ( the original head had air-pump ports)
- kent md266 fast road cam timed precisely according to instructions
- maniflow lcb street header for 1275
- rc-40 competition exhaust system ( modified to fit sprite)
- dellorto dhla (dlha?) 40 sidedraft with 36mm venturi's
Should I just adjust the timing by ear to the maximum RPM?? and not worry about
it, or is there some special method I should follow involving a full moon and a
dead chicken?? I can't seem to find this exact info in the david vizard book (
I
wish it had an index :-(
The book I have on Dellorto's says that modified engines may require much more
of an advance than a 'stock' engine, but it doesn't go into any specifics.
Any suggestions???
As far as the Dellorto, I followed the jetting info pretty closely for the
a-series engine based on the vizard book recommendations, and that in my
Dellorto book ( they were in the same ball part), but I can't seem to get it to
idle smoothly on just the idle jet, I have to keep the throttle plate cracked.
I
started out with the idle screws out 2.5 turns each, and tried screwing them
in,
but this seemed to only make the engine run worse.
The engine also seems to stumble a little bit when I first open the throttle,
but I notice that this problem lessens the more I advance the timing.
Maybe I'm just trying to be too precise on this stuff, and all I'm supposed to
do is fudge with the timing and idle until it seems to run OK.
BTW- with the timing set at ~20 degrees, I still have no 'backfire' when I let
off the gas when driving.
Regards,
Bryan
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