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Old 05-04-2016, 05:30 PM
L78steve L78steve is offline
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Default L78 Total advance

What are you L78 gurus running for total advance? I'm running 36 and think it could benefit with a bit more.
No spark knock at all with pump premium.
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  #2  
Old 05-04-2016, 07:26 PM
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Default Re: L78 Total advance

What is your initial set at?? What rpm does the total come in at?? Are you running vacuum advance??

Assume this is stock L78 specs...compression/cam??

Auto? stick? rear gear?

wilma
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Old 05-04-2016, 07:37 PM
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Default Re: L78 Total advance

1. Possible it would benefit with a couple more degrees.
2. Remember, just because you don't hear an audible ping, doesn't mean there is no detonation. The detonation you hear is just the extreme. It starts a bit before it is audible.

3. While I agree with Tom that all the numbers need factored in, I am going to ASSUME you are fine with the all around performance, and already have the curve and vac dialed in. You are just contemplating advancing a bit. Also ASSUMING you are running the vacuum to straight a manifold vac and not a "ported spark" source. That takes the vac advance out of the equation under load.

If all of that is correct, I would bump it up to 38 and give it a shot. Because you called it an L78, again, I am ASSUMING you mean close to stock compression, cam, etc. I will be the first to admit it has been many years since I helped tune an L78. So many years, we still had regular leaded gas available (without going to the airport). Seemed the ones I worked on liked right at 36 total (excluding vac of course).

Seat of the pants can be very deceiving. Many times we "feel" a difference just because we WANT a difference. If you have a Gtech or something similar, you could make back to back runs in an appropriate area to see if there is any measurable difference. If there is no performance benefit, I would put it back to 36 just in case there is an inaudible ping at 38.

Way more than you asked, but trying to cover all the bases in one post.

Good luck.
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Old 05-04-2016, 08:14 PM
L78steve L78steve is offline
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Default Re: L78 Total advance

Stock L78, Full Vac avail. to Dist.Not that it matters at WOT.Car runs good just wondering if anyone is running more total than 36. With 11:1 I'm wondering why no spark knock and run on after shut down with today's fuel unless I'm not running enough advance for max power, even if I need to add some racing fuel to the mix is OK if a timing bump will help.
Curve and Vac is dialed in, Static is where ever it needs to be for total setting. As long as the starter will crank it I don't worry about initial too much but I will guess its about 12.
Tom are you having any issues with ping on your cars?
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Old 05-04-2016, 09:32 PM
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Default Re: L78 Total advance

My cars won't run on the 93 pump stuff without a serious dose of race fuel or av gas. I think we run 36* total..16-18* initial...all in by 3,000rpm. Vac adv is hooked up to manifold vacuum.

I'm amazed you can use the pump stuff and not have pinging...did you ever calculate the compression ratio when the motor was apart? Those rect port heads are notorious for having bigger chambers than advertised.

tom
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Old 05-04-2016, 11:42 PM
L78steve L78steve is offline
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Default Re: L78 Total advance

Tom, the only difference is i'm all in at 3700. I never calculated CR but engine is bone stock std. bore heads uncut. I'll give it a 2 degree bump and see. Stock Garner exhaust so if it pings I should hear it.
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Old 05-05-2016, 12:38 AM
JRSully JRSully is offline
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Default Re: L78 Total advance

Speak to Eric at Vintage, he did my orig L78 dizzy. Basically bone stock L78/4spd/3:73 except for headers. Timing is all in at 3k and engine responds very well to that. Also run a Crane breakerless ignition, dead reliable for a bunch of years now.
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Old 05-05-2016, 12:48 AM
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Default Re: L78 Total advance

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: JRSully</div><div class="ubbcode-body">Speak to Eric at Vintage, he did my orig L78 dizzy. Basically bone stock L78/4spd/3:73 except for headers. Timing is all in at 3k and engine responds very well to that. Also run a Crane breakerless ignition, dead reliable for a bunch of years now. </div></div>

You still running that rod on diesel??
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Old 05-05-2016, 11:04 AM
JRSully JRSully is offline
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Default Re: L78 Total advance

steady trips to the local airport takes care of the fuel issues. And, as a matter of fact, I'm now waiting to see what VW is going to offer to buy back my Passat diesel, It's too bad cause I love the car. 600 miles out of a tank of gas, tons of torgue and it is fast. VW is either offering to neuter the car or buy it back
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Old 05-05-2016, 01:48 PM
L78steve L78steve is offline
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Default Re: L78 Total advance

I would not give up the Diesel VW. Your PCM has a custom performance tune that you cant get any longer.
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