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914World.com _ 914World Garage _ Air fuel
Posted by: worn Oct 1 2014, 07:03 PM
As one can derive from following these pages I have rebuilt a 2056. After that I have had problems with cooling. On the trip to ockteenerfest I was able to make close to all out full power and still stay below 400 on the cht. But, it was at an air fuel ratio of between 10-11. Seems awfully rich to me, but I am a chemist looking for a perfect match. Fuel mileage went by the board but I wasn't driving 55 worrying that the engine would over heat. Yeah, it is stock FI with a webcam.
So,is this where I am going to tune around, or is it richer than it should be. Appreciate the wisdom. Also, when you drive 900 miles and have your alternator pulley separate in two, this is the group that will save your bacon. Thanks.
Posted by: Bleyseng Oct 2 2014, 06:57 AM
Using what to determine the A/F ratio? How many miles on the engine rebuild?
Posted by: gereed75 Oct 2 2014, 07:44 AM
As one can derive from following these pages I have rebuilt a 2056. After that I have had problems with cooling. On the trip to ockteenerfest I was able to make close to all out full power and still stay below 400 on the cht. But, it was at an air fuel ratio of between 10-11. Seems awfully rich to me, but I am a chemist looking for a perfect match. Fuel mileage went by the board but I wasn't driving 55 worrying that the engine would over heat. Yeah, it is stock FI with a webcam.
So,is this where I am going to tune around, or is it richer than it should be. Appreciate the wisdom. Also, when you drive 900 miles and have your alternator pulley separate in two, this is the group that will save your bacon. Thanks.
Timing is very critical to engine temps. Too much advance will cause high temps. Especially at higher compression ratios one or two degrees matter. Not sure what the specs are for your engine but check it
Posted by: worn Oct 2 2014, 01:49 PM
Using what to determine the A/F ratio? How many miles on the engine rebuild?
AEM broadband meter. About 4-5,000 miles.
Posted by: worn Oct 2 2014, 01:54 PM
As one can derive from following these pages I have rebuilt a 2056. After that I have had problems with cooling. On the trip to ockteenerfest I was able to make close to all out full power and still stay below 400 on the cht. But, it was at an air fuel ratio of between 10-11. Seems awfully rich to me, but I am a chemist looking for a perfect match. Fuel mileage went by the board but I wasn't driving 55 worrying that the engine would over heat. Yeah, it is stock FI with a webcam.
So,is this where I am going to tune around, or is it richer than it should be. Appreciate the wisdom. Also, when you drive 900 miles and have your alternator pulley separate in two, this is the group that will save your bacon. Thanks.
Timing is very critical to engine temps. Too much advance will cause high temps. Especially at higher compression ratios one or two degrees matter. Not sure what the specs are for your engine but check it
I have tried timing stock and then tweaked from there. A lot of people say retarded spark is the one to watch for...
I tried to find a sweat spot but am open to suggestion. Real question is have I solved the problem (for the first time) in an appropriate way. People say with an altered cam you need carbs, which can be a means for adding fuel. Did I arrive at the same place?
Posted by: Cap'n Krusty Oct 2 2014, 02:16 PM
I may be way off, but it seems to me I've heard that the heat/retarded timing problem is with water cooled engines. Can't cite the source; too long ago to remember, and I figured it didn't really apply to what I was doing.
The Cap'n
Posted by: Mblizzard Oct 2 2014, 05:19 PM
Ok you have likely done this but check your spark plug gaps and timing. If you don't have it, get Chris Foley's MPS adjustment kit. Also review http://members.rennlist.com/pbanders/manifold_pressure_sensor.htmMPS adjustment information.
Check your fuel pressure, verify your advance is working correctly, and make sure your cooling flaps are correct.
Posted by: Bob L. Oct 2 2014, 05:32 PM
People say with an altered cam you need carbs, which can be a means for adding fuel. Did I arrive at the same place?
There are cams designed for FI and some for carbs. So it depends on which one you have.
Posted by: Mark Henry Oct 2 2014, 07:38 PM
400F is too hot, I aim for 12.5 to 13:1 and 28* total advance (about 7*BTDC static) timing.
400F is my max pulling a long steep hill, 325-350F at cruse is more normal.
Too much advance will make it hot.
This is on a few performance carb and PEFI engines I've built.
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