Peter,
No, I didn't have the vacuum disconnected when I timed at 4000rpm. I didn't
think I was supposed to. Doesn't it need to be connected to make sure the
engine is timed at 'full advance', or am I missing something here. Would that
also explain why I two distinct timing marks with my strobe light?
In any case, what exactly am I shooting for?, what is setting the timing at 30
degrees supposed to do for me?
regards - Bryan
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>To: Bryan Vandiver <Bryan.Vandiver@eng.sun.com>
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>Subject: Re: Speed timing, and gas mileage
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>Did you have the vacuum advance disconnected when you did the 4000 rpm
>total advance?? The engine is not under load so would have a high
>vacuum. The total advance should be done with the vacuum disconnected,
>and should be around 32~36 degrees.
>Peter S.
>Charlotte NC
>
>Bryan Vandiver wrote:
>>
>> 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
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