David Jenkins
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| posted on 29/7/03 at 12:46 PM |
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Unleaded timing
Can anyone suggest a timing setting for an unleaded 1600 crossflow?
My Haynes manual only speaks leaded...
cheers,
David
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Simon
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| posted on 29/7/03 at 01:48 PM |
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David,
I'm assuming that the engine now has hardened valve seats etc to make it an unleaded engine.
If that's the case will the standard timing not be satisfactory/appropriate given that the (and this is my understanding) timing adjustments
made to a "lead" engine running unleaded fuel engine are so it burns cooler.
Or is this what you were thinking, and wanting someone else to confirm:-)
ATB
Simon
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David Jenkins
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| posted on 29/7/03 at 01:52 PM |
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First - yes, I do have hardened valve seats!
Second - I thought that unleaded has a lower RON value than 4-star, so the timing has to be set back a bit (or should I just use premium unleaded?)
David
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Peteff
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| posted on 29/7/03 at 02:04 PM |
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Buy some octane booster and put that in your tank. Millers or similar, it works in pintos, definite improvement on unleaded fuel.
yours, Pete.
yours, Pete
I went into the RSPCA office the other day. It was so small you could hardly swing a cat in there.
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David Jenkins
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| posted on 29/7/03 at 02:21 PM |
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That's not for me, Pete... the reason I had hardened valve seats fitted was to keep things simple - I can just fill it at any petrol station,
with no additives, or LRP, or whatever.
The reason for my original question was that cars timed for leaded petrol tend to pink when using unleaded. I probably need to come back 1 or 2
degrees, but I'd like a starting point to start off with (literally!).
cheers,
David
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timf
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| posted on 29/7/03 at 02:23 PM |
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definatley dont just use plain unleaded
as the octane rating will result in destroyed pistons in less than 1000 miles
(experience) use super or an octane booster.
Tim
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David Jenkins
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| posted on 29/7/03 at 02:28 PM |
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I guess that's why you have to set the timing back a bit - to stop knocking/pinking on a lower octane fuel.
DJ
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Stu16v
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| posted on 29/7/03 at 06:17 PM |
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David, there isnt really a hard and fast figure. The timing depends on soooo much, compression ratio, different carbs, cam, exhaust etc, etc. I would
suggest that 3 to 5 deg less advance than Mr Haynes states initially, and save yer pennys for a rolling road sesh.
HTH Stu.
Dont just build it.....make it!
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Mark Allanson
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| posted on 29/7/03 at 07:12 PM |
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Backing up what Stu said, I have just checked out my Data Manuals, all the HCS/OHV kent type engines are backed off by 4 degrees when using 95 RON
unleaded
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David Jenkins
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| posted on 29/7/03 at 08:10 PM |
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Many thanks, Mark & Stu! Sort of what I expected...
DJ
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