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PostPosted: Fri Apr 22, 2022 12:35 pm 
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TBI Slant 6
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Joined: Tue Aug 19, 2003 3:52 am
Posts: 201
Location: Helsinki Finland
Car Model: 1966 2D Dart
In my experience the 225 likes quite limited max advance compared many other old engines. The total advance of 30-32 degrees at WOT seem to enough for naturally aspirated big slant.

As the small version has more conventional bore/stroke -ratio and the connecting rod length vs stroke are closer to many other engines of that era I assume the small slant (170) could have/like different ignition advance settings.

Are they ao different? What is the sweet spot for 170 max advance?

Example. I was testing my new rebuild 170 with no load at 2500-3000. I had already increased ignition at 40 kPa to 45 degrees because engine was revving more easily. This advance at ECU equals that: ”basic advance + mech advance at full + vacuum advance at full”. When I set 45 => 48 the engine felt even more happier.

With 225 just 40 degrees at that area was enough.

_________________
1966 Dodge Dart. Slant six 170 cu in. A904 automatic transmission. 7 1/4" rear end.

E85 fuel (based on recycled waste). Ported head. O/S valves. Balanced internals. TO3/4, Maxxecu, OGC cam. Hughes custom converter. 4.10SG rear.


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PostPosted: Mon Apr 25, 2022 7:23 am 
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TBI Slant 6
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Joined: Tue Aug 19, 2003 3:52 am
Posts: 201
Location: Helsinki Finland
Car Model: 1966 2D Dart
OK. I will test it with 34-36 degrees and -2 degrees / 100 kPa

_________________
1966 Dodge Dart. Slant six 170 cu in. A904 automatic transmission. 7 1/4" rear end.

E85 fuel (based on recycled waste). Ported head. O/S valves. Balanced internals. TO3/4, Maxxecu, OGC cam. Hughes custom converter. 4.10SG rear.


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PostPosted: Mon Apr 25, 2022 8:29 am 
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Joined: Mon Oct 21, 2002 11:08 am
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Location: Blacksburg, VA
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I would say 4-6 deg more advance across the ranges (RPM and kPa) is a good place to start. Probably idle can be same or even less advance than the 225, though.

Lou

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"You mean you still have a Slant 6 in that thing?"


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PostPosted: Mon Apr 25, 2022 8:35 am 
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TBI Slant 6
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Joined: Tue Aug 19, 2003 3:52 am
Posts: 201
Location: Helsinki Finland
Car Model: 1966 2D Dart
As the N/A 225 was happy with 30-32 the small 170 would like something in between 34 and 38? I think I choose conservative value as I have understood E85 does not ping as a warning. It just kill the engine.

_________________
1966 Dodge Dart. Slant six 170 cu in. A904 automatic transmission. 7 1/4" rear end.

E85 fuel (based on recycled waste). Ported head. O/S valves. Balanced internals. TO3/4, Maxxecu, OGC cam. Hughes custom converter. 4.10SG rear.


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PostPosted: Mon Apr 25, 2022 11:49 am 
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Joined: Mon Oct 21, 2002 11:08 am
Posts: 15359
Location: Blacksburg, VA
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I have zero experience with E85. I would imagine it burns more slowly than gasoline? That would indicate you would want more advance yet, but others can perhaps comment on this. Maybe search web for results on other engines first?

Probably start with 34 under WOT and go to less advance to be safe and see if it gets worse? If you are worried about detonation/damage...

Lou

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"You mean you still have a Slant 6 in that thing?"


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PostPosted: Mon Apr 25, 2022 12:01 pm 
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TBI Slant 6
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Joined: Tue Aug 19, 2003 3:52 am
Posts: 201
Location: Helsinki Finland
Car Model: 1966 2D Dart
Many articles says ethanol flame speed is higher. This makes possible think about less advance. But in many engines the ignition is a compromise and with ethanol it is possible get all needed advance.

_________________
1966 Dodge Dart. Slant six 170 cu in. A904 automatic transmission. 7 1/4" rear end.

E85 fuel (based on recycled waste). Ported head. O/S valves. Balanced internals. TO3/4, Maxxecu, OGC cam. Hughes custom converter. 4.10SG rear.


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