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Ignition timing on 360 engine! |
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Frank T
AMC Apprentice Joined: Mar/08/2013 Location: Denmark, Europe Status: Offline Points: 106 |
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Posted: Mar/02/2015 at 5:32am |
I have a 360 engine with Edelbrock performer cam, intake and 600Cfm carburator, any good ideas to make my engine run with the perfect iginition timing
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1979 AMC Spirit 360
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Ollie
AMC Addicted Joined: Sep/17/2012 Location: Brandon, MS Status: Offline Points: 2801 |
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Set your timing with a Vacuum gauge. Set at highest vacuum reading. You will be dialed in at optimum.
Ollie |
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Lenni AMC
AMC Nut Joined: Jun/05/2011 Location: Iceland Status: Offline Points: 420 |
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36° total timing is a good starting point..
Set at 3000-3500 rpm Just remember to unplug the vac advance from the distributor when setting the timing at 36°
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AMC Gremlin w/401
6.212 @ 117.01 - 1/8 Mile 9.785 @ 133.11 - 1/4 Mile https://www.youtube.com/channel/UCikyNqrfpMB8VzLd910Hkhg https://rbjracing1.wixsite.com/website |
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ridler3d
AMC Apprentice Joined: Nov/07/2009 Location: florida Status: Offline Points: 186 |
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Never thought of a vacuum guage
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Boris Badanov
AMC Addicted Joined: Dec/14/2013 Location: NH USA Status: Offline Points: 4209 |
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With all due respects Ollie I disagree with setting timing with a vacuum gauge.
Most engines will make more vacuum with idle timing settings that will send the total timing well past the danger zone.
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Gremlin Dreams
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FSJunkie
AMC Addicted Joined: Jan/09/2011 Location: Flagstaff, AZ Status: Offline Points: 4741 |
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This has been tested many times before and most people agree to the numbers.
10-15 initial at idle 30-35 total at 3500-4000 RPM, vacuum advance disconnected. An additional 15-20 from the vacuum advance. |
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1955 Packard
1966 Marlin 1972 Wagoneer 1973 Ambassador 1977 Hornet 1982 Concord D/L 1984 Eagle Limited |
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purple72Gremlin
AMC Addicted Charter Member Joined: Jul/01/2007 Location: Illinois Status: Offline Points: 16591 |
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I was taught that using vaccum to set the ti ming was the best way......But I found out that that would give it too much initial. .....
So I usually go by ear, or a combi`ation of going by ear & a timing light. I would prefer to use a distributor machine, but no access to one. So I have used a timing light with the knob on it. It works. And I almost never go by factory settings. |
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Frank T
AMC Apprentice Joined: Mar/08/2013 Location: Denmark, Europe Status: Offline Points: 106 |
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Thanks so fare, I have also this distributor, anyone with exerience with that?? or is the original Motorcraft actualy better?http://www.ebay.co.uk/itm/AMC-JEEP-CJ5-CJ7-304-360-401-V-8-HEI-DISTRIBUTOR-6512-BK-/371072745638?pt=Motors_Car_Truck_Parts_Accessories&hash=item5665a8c0a6
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1979 AMC Spirit 360
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uncljohn
AMC Addicted Joined: Jan/03/2013 Location: Peoria AZ Status: Offline Points: 5394 |
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Setting timing with a vacuum gauge is one way to get close, and I have used it a number of times when lacking a timing light. You set it at Idle and idle by spec is 600 rpm.
Timing adjustments according to TSM I have in front of me are made at 500 rpm with the vacuum line disconnected. And when done reset idle rpm to the manual spec of 600 rpm or what ever your personal preference is. This is to insure that the mechanical advance mechanism is not advancing the timing. Depending on which distributor you use, mechanical advance generally starts at 900 rpm. But using this method, done with the vacuum line connected generally as others said gives too much advance. Thus if I use this method, I fined max. vacuum and then retard the distributor a tad. It works. A timing light works better. Insure basic timing done with a light, again factory spec is 5 degrees. If you use another number, it is personal preference. Mechanical advance generally will be an additional 12 to 16 degrees at about depending on the distributor. Vacuum advance will depend on the distributor also, but is generally considered to be 17 to 19 degrees. Thus maxim advance at an rpm about 2000 rpm and a maximum vacuum reading (do the adding) would be 12+17=29 degrees to 16+19=35 degrees. Add to those numbers your initial advance setting and that will define your advance curve. As your distributor, depending on the distributor, should have all mechanical advance in by about 2000 rpm, add that to vacuum advance and any rpm number over 2000 rpm is going to be the same number as long a vacuum stays the same. And unless you have the capability of changing the mechanical advance built into the distributor and/or the vacuum can which defines when vacuum advance kicks in that is also your limitations. One timing is set and a method is to use 500 rpm until timing is set and then reset curb idle rpm to 600 rpm in drive or 650 rpm if standard transmission in neutral, you get what you get. I personally like a 450 rpm curb idle when I can get it. The limits being what ever the cam I am using will let me run, or as slow as I can get it to run. Once initial timing is set and I use between 8 - 10 degrees generally, I choose a vacuum can (if I can) that lets maxim vacuum advance come in 1 inch below the maximum vacuum reading taken at curb idle. This is optimum for cruise conditions where I drive most of the time. The Rest? Takes care of itself. If you really have no idea what distributor you have they are all more or less going to get the job done and all parts on the distributor are functional forget all of the above, set initial timing to your preferred setting as slow as you can get the engine to run, preferably at an rpm under 600 rpm, with the vacuum line disconnected. Use a vacuum gauge at that point in time to set idle mixture screws, 2 for a 2 or 4 bbl carb, 1 for a single bbl carb for a maximum vacuum reading at the same rpm used to set timing with and then reset curb idle rpm to your preferred number. A TSM will say something like 600 rpm with automatic in drive and 650 rpm with a standard transmission. So when done, adjust curb idle to idle rpm in manual or what ever you like and call it good to go and forget the rest. As to the affect on pinging? That in part is going to be a function your engines compression ratio and the octane rating of your gasoline being used. If in doubt, buy premium gas and tune using it. The advantage? It runs better. Another advantage? In Europe, gasoline octane is higher than here in the US. Here in the US. I have seen premium as low as 90 octane. Where I live it is 91 octane. In other parts of the country it is as high as 94 octane and maybe 95. The problem with pinging will in part relate to your engine compression ratio, the gasoline available and tune you use. Most early 70's V8 engines were designed to run premium gasoline which at that time was leaded 100 octane. No lead 93 octane is close to that. Edited by uncljohn - Mar/05/2015 at 8:55am |
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70 390 5spd Donohue
74 Hornet In restoration 76 Hornet, 5.7L Mercury Marine Power 80 Fuel Injected I6 Spirit 74 232 I-6, 4bbl, 270HL Isky Cam |
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Boris Badanov
AMC Addicted Joined: Dec/14/2013 Location: NH USA Status: Offline Points: 4209 |
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+1 No lead 93 is roughly 97 according to a couple of web sites.That's rougly the same as standard premium gas from name brand gas stations in 1970. But there is no lead today, much better for engine life but highly detremental on pre 1970 exhaust valve seats. I valve job with hardened seats and stainless exhaust valves is a good idea for an older daily driver project. If it is a short run street fighter or a hundred miles a year cruise night special, don't sweat it, just mix in a little leaded race gas. Sunoco "Ultra 94" or other 94+ super unleaded's are 98+ by the old MON "Motor" method. Pure Toluene, if you can get it, is over 120 PN. |
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Gremlin Dreams
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