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Re: Speed timing, and gas mileage

To: Bryan Vandiver <Bryan.Vandiver@Eng.Sun.COM>
Subject: Re: Speed timing, and gas mileage
Date: Mon, 19 Jun 2000 18:15:10 -0400
Cc: spridgets@autox.team.net
References: <200006191854.LAA20351@shorter.eng.sun.com>
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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