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Old 09-25-2011, 05:50 PM   #1
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Recurve 1990 454 chev distributor

Is there a simple way to recurve the 454 for better gas mileage? I have some mechanical skills and tools. I remember you used to be able to loosen a nut and turn the distributor a little to advance or retard it in the old days for better starting.
Doug
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Old 09-25-2011, 06:24 PM   #2
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sounds to me like you need a timing light, get the proper procedure and set your time correctly. I just reread your post. are you having a starting problem or trying to get better mileage?
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Old 09-26-2011, 09:06 AM   #3
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Trying to get better mileage!
From the main question
"Is there a simple way to recurve the 454 for better gas mileage?"
I am sure that a lot of 454 owners have tried some things. Just wondering what works and what doesn't.
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Old 09-26-2011, 05:50 PM   #4
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are you wanting to change the timing curve ( the rate of timing advance )? or the static timing?
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Old 09-26-2011, 06:48 PM   #5
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for the best fuel economy run as much timing with out pinging,,,, just keep in mind if your vehicles weight(load) goes up, and/or fuel octane goes down, or engine temp just 20' degrees you will need to re-time.
do not set it with a 16K curb weight and hitch on a 7k lb trailer and expect it to work either.
Is your vehicle carbed without computer, carbed with computer or Throttle Body Injection?
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Old 09-27-2011, 09:09 AM   #6
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Thanks for the info. It has a Throttle Body on it. I will advance it a little and try it too see if it makes much difference. I am sure I can get it figured out. We run dry, no trailer or toad. Maybe a hitch hauler for scooter once in a while. We are trying to plan a trip from Il to SC for October.
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Old 09-28-2011, 02:19 PM   #7
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Quote:
Originally Posted by pinebear View Post
Thanks for the info. It has a Throttle Body on it. I will advance it a little and try it too see if it makes much difference. I am sure I can get it figured out. We run dry, no trailer or toad. Maybe a hitch hauler for scooter once in a while. We are trying to plan a trip from Il to SC for October.
Be sure to ollow the correct procedure on setting timing or the computer will readjust right back where it was.
I'm not 100% sure but i think there is a connectoer to unhook once you are up to running temp.
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Old 09-30-2011, 05:16 PM   #8
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Messing too much with the advance on a motorhome may be asking for trouble. These engines work hard most of the time and extreemly hard some of the time. Too much advance and you may be draining aluminum from your pan, not oil. If you really need improved mileage drive 5MPH slower. This will give you a greater improvement than messing with the timing.

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Old 09-30-2011, 06:51 PM   #9
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You get it to where it is pinging or knocking, you will burn a hole in a piston. I would leave the timing set at factory specs on a motorhome.

What kind of mileage are you getting and at what speed. The best way to get the mileage up is to slow down 5 mph.

Ken
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Old 10-01-2011, 09:18 AM   #10
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In answer to your question, if you have Throttle body Injection (TBI) you have a computerized engine control management (ECM) system (OBD1 in this instance). Only mechanical adjustment that can be made is the base timing. All other timing advance is programmed into the ECM. The ECM is monitoring O2 sensor, engine RPM, Vacuum, and engine temperature to determine how much fuel and timing advance is needed at any given point. Transmission shift points may also be factored in. Only way to change the timing curve is to reprogram the ECM chip. While it is possible to invest in the hardware and knowledge to change this you really need to know what your doing (you are not trying to tune a race car). While companies like Banks do provide updated programming for ECMs for later model OBD2 based systems, that is done in concert with exhaust/intake hardware upgrades. The programming changes allow the engine to take advantage of the new air flow characteristics.

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Old 10-01-2011, 10:00 AM   #11
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You can buy springs and weights from a place like Summit Racing to change the spark advance curve.
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