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| Timing settings on a stock 71 https://slantsix.org/forum/viewtopic.php?t=67299 |
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| Author: | adam83 [ Thu Jun 15, 2023 12:53 pm ] |
| Post subject: | Timing settings on a stock 71 |
I just recently got my 71 fired back up after some refurbishment. Had to pause on the fine tuning due to leaking radiator. Just got that all sorted out, and now I need to tune. This engine is completely stock (besides baffles being added to oil pan) and low mileage. Its an automatic trans. It has points and it's original 1920 carb, fully rebuilt. Stock distrubutor, no a/c. Idk if clean air package was an option in 71, but my car does not have it. I believe for a 71 base timing is supposed to be 0 degrees. I've read here that you cannot bump up the timing as far as you can on later engines, and to stick with about 3btdc initial. Does anyone run a stock 225 with points and no egr? What is your initial set to? How many degrees initial+mechanical do you run? How much total timing? What rpm does your engine reach total timing? How much manifold vacuum do you see at idle? What is your idle speed set to? I'm trying to get the best gas mileage and efficiency I can. |
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| Author: | Rick Covalt [ Thu Jun 15, 2023 5:08 pm ] |
| Post subject: | Re: Timing settings on a stock 71 |
I don't think I have ever ran less than 6 degrees on any car or truck I have ever had. Does anyone know why the "0" degrees or even very low degrees was used. I am guessing something to do with emissions? |
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| Author: | volaredon [ Thu Jun 15, 2023 5:43 pm ] |
| Post subject: | Re: Timing settings on a stock 71 |
I've always treated advertised specs whether on an underhood decal or out of a manual as only a starting point. Then tweak until it runs the best it can from there. Though I've heard (mostly online, I have never been there) that in Cali they check where your timing is set up on a smog test and if it's anything other than "exactly" what is on that sticker, they flunk the car. |
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| Author: | kesteb [ Fri Jun 16, 2023 9:38 am ] |
| Post subject: | Re: Timing settings on a stock 71 |
The factory setting is 0* initial. If this is a stock OEM distributor, this means that the governor is a 15R. Which has 30* mechanical built in. The \6 likes around 30* mechanical advance. Depending on how you drive the car, the current compression ratio, and fuel quality, you may be able to advance the initial setting. |
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| Author: | adam83 [ Tue Jun 20, 2023 9:52 am ] |
| Post subject: | Re: Timing settings on a stock 71 |
Assuming the hole in the timing tab is TDC, so far I've got my initial set to about 1 degree, and at 3000 it is sitting about 32. No pinging, but I haven't tested under load yet. My dwell is sitting at 42. My idle hovers gradually between about 735 and 748 (only noticeable on the rpm readout on my timing light, you dont actually hear the engine doing this), and my vacuum at idle is about 19in after adjusting the idle mixture screw to optimal. Do these numbers sound like a good baseline? Should I have more vacuum at idle? My idle feels like it could easily drop another 50rpm and still run great, any benefit to dropping it? |
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| Author: | Dart270 [ Tue Jun 20, 2023 1:20 pm ] |
| Post subject: | Re: Timing settings on a stock 71 |
Those numbers sound good to me. You could drop the idle, but I see no reason to do that. If you prefer the feel, then do it. Lou |
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| Author: | adam83 [ Tue Jun 20, 2023 2:36 pm ] |
| Post subject: | Re: Timing settings on a stock 71 |
If there's no benefit to dropping idle, and the idle is within spec, I'll just leave it. What rpm should total advance be in at? |
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| Author: | Dart270 [ Wed Jun 21, 2023 3:41 am ] |
| Post subject: | Re: Timing settings on a stock 71 |
Every car (year, engine, sometimes by different states or options like AC) had a different advance curve. You should be all in around 3000 RPM. I would drive it for a while and see how it runs. Lou |
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| Author: | adam83 [ Fri Jun 23, 2023 7:25 am ] |
| Post subject: | Re: Timing settings on a stock 71 |
Timing is all in at 3000. I adjusted valve lash while hot. Everything was loose, I set the intakes to .010" and exhaust to .020" I went from 18.5/19" Manifold vacuum before lash, to 16" after valve lash. Is this acceptable? It doesn't feel or sound like they were adjusted too tight, and the engine doesn't appear or smell like it's running rich. |
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| Author: | volaredon [ Fri Jun 23, 2023 1:18 pm ] |
| Post subject: | Re: Timing settings on a stock 71 |
Weird as whenever I've adjusted valves a on a /6 in the past my vacuum seemed to improve after the adjustment vs prior, if it changed at all. |
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| Author: | volaredon [ Fri Jun 23, 2023 1:20 pm ] |
| Post subject: | Re: Timing settings on a stock 71 |
On dropping the idle speed part of what you were saying, if you can do so.... Less likely to creep while in gear such as when sitting at a light |
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