Tips and Modifications for improving fuel economy?

[ClydesdaleKevin]

Sent: 9/24/2005 7:22 PM

I went through the message boards, and while this topic is addressed here and there often, I couldn't find a thread that dealt with it specifically, so decided to start a very specific thread.

What does everyone recommend as being the best ways of improving the fuel economy of our rigs?

I am getting between 6 and 9 mpg, depending on terrain and driving conditions, on our '72 413.  Since my wife and I just took a job on the Renaissance Faire circuit, we'll be driving a lot...for instance, we have to be in Plantersville, TX on October 10th.  This is over 900 miles from where we are now.  Even a MARGINAL improvement in gas mileage would pay off big dividends in the long run on routine long voyages.

So...where do I start?

Areodynamics is out...lmao...ALL of our rigs are about as aerodynamic as a sail.  So...where to start?

Lean out the carb slightly?  Headers?  Full-flow air filter?  Play with the timing?  Incidently, how DO you go about timing a 413?  I read the factory manual, and can't seem to make heads or tails out of timing marks...where are they, and what is the simplified version of the procedure?

Thanks!

Kev



From: denison
Sent: 9/24/2005 9:10 PM

The 413-1 timing marks are: a slot on the crankshaft damper, and a metal flange that sticks out from the timing cover, just above the cranksahft damper, and slightly toward the passenger side of the engine. I find it VERY difficult to see the marks by leaning over the engine. Holding the timing light close to the spinning fan blades I have to hold a small mirror in my other hand, angled ‘just so’.
However, thanks to the open area between the frame rail and the floor of the coach on my winny, I can get the timing light connected up and pass it down beside the rocker cover, then crawl underneath and point the timing light in the timing marks from just above the frame rail. I can just barely turn the (loosened) distributor from down there, and I am not in danger of getting my fingers sliced off.
I had also made my own crude timing marks. I lined up the slot in the damper with the 8 degree BTDC mark, then painted a line on the bottom of the crankshaft damper, and a matching line on the front lip of the oil pan. This allowed me to check the timing from directly under the radiator (when the two lines were lined-up), but I couldn’t turn the distributor from down there.
The service manual says the timing is 5 degrees BTDC, plus or minus 2.5 degrees. That’s with the vacuum line disconnected from the carb. So I aim to set mine at 8 degrees BTDC. As long as the engine is not pinging you are probably okay being a little early. I might try 9 or 10 degrees BTDC this November when we start for Texas.
I don’t think headers or a different air intake system will make any difference. Leaning out the mixture might help, or it might cause the exhaust manifolds to warp/crack, or an exhaust valve to burn. If you decide to lean it, be sure to let us know how it goes. Keep track of the color of your spark plugs too. I like mine to be not-quite-white in color.
It can also help to paint the slot in the crankshaft damper white, and to clean up and paint the marks on the timing chain cover white too.



From: denison
Sent: 9/24/2005 10:03 PM

the timing flange on the front of the timing chain cover, and some painted marks on the crankshaft damper too. I aim my timing light in from the left side of that opening, behind the radiator.



From: cooneytunes
Sent: 9/25/2005 1:10 AM

In my opinion one of the first things to do to save on fuel mileage is, SLOW down a bit....these 440's and 413's have little problem doing 65 & 70 mph..and more if they are tuned and running at their peak.....back er' down to 55 and see the improvement.....I found about a 25 to 30% improvement which also depends on terrain and weather condition. Trying to keep the vaccum reading above 10 inches.....going up hill this is impossible, so compensate on the down hill and flat parts.let it roll going down a hill so you won't need as much throttle to get you over the top of the next uphill.....keep that vaccum as high as possible..also what uses a lot of fuel is, to get these things going from a dead stop.....so once your on the road and moving at 55...... go............ don't stop until you must ......they are much better on fuel in the long run than a whole bunch of short ones...Keeping you rig lubed and check your tire pressure often and keep it inflated to the reccomended pressure for you rigs tires..Also UPS doesn't clean and wax their planes to make them look good.....they claim, it save them millions of dollars in fuel cost.....so.......... keep your rig clean & waxed, and according to UPS, this causes less friction or drag, improving fuel mileage....... Just some thoughts on how to save a few dollars in fuel....

Timmy



From: The_Pharaoh_Rulz_
Sent: 9/25/2005 9:47 AM

How about other things which may affect mileage, like...  Tire pressure, condition and gapping of spark plugs, frequent oil changes, etc.? 

- Sob



From: galaxieman59retr
Sent: 11/18/2005 1:10 PM

Try adding acetone to the fuel. About 3 OZ. per 10 galllons. There is a web site for this. Just search for fuel economy and it will come up.



From: MacD22C
Sent: 11/22/2005 12:49 PM

HI, I also have a '72 413.  I got a BIG improvement with a set of headers and dual all the way back.  About 1mpg and up to 5 MPH on the big hills.  I got a set of Doug Thorly headers as they were recomended and are extra thick 14 ga wall and chromed for rust resistance. 
  I saved $200 by putting them on my self - but while the RH side was a snap, the LH side was very dificult as the rngine is offset to the left and the brake master cylinder and bracket is in the way.
Good luck,
John



From: ClydesdaleKevin
Sent: 11/22/2005 8:11 PM

How much did the headers themselves cost you, if you don't mind me asking, and where did you get them?  The Ark is going to need a whole new exhaust in a year or so, so I'm thinking of going with headers.

Kev



From: denison
Sent: 11/25/2005 4:38 PM

The original type 413 exhaust manifolds seem to go for $150 plus shipping on ebay. They are new repros.



From: Slantsixness
Sent: 11/28/2005 8:40 AM

Kev,
Headers can be headaches. we'll get the MPG up on the Ark next monday, without headers. While they are nice to consider, and some, not all, can improve economy. Improved MPG only happens when used with the proper muffler, pipe size and post header exhaust restriction. For any mopar, I would also suggest a  post header crossover pipe in a dual exhaust system. Why? the exhaust flow will increase, the engine runs smoother, the exhaust will be quieter, and that means the mpg goes up again, too!

The original type 413 exhaust manifolds are actually not very restrictive to begin with.

Tom



From: cooneytunes
Sent: 11/28/2005 8:39 PM

I think one of the biggest thing people forget when they go to headers is "Engine Backpressure"....These engines were designed from the factory, to run with a certain amount of backpressure.... adding headers eliminaltes most of the backpressure. Without making other changes, this alone (just adding headers) will not improve fuel mileage, and can cause a host of other problems.

Timmy



From: The_Pharaoh_Rulz_
Sent: 11/29/2005 8:13 AM

For more information on headers, use the Message Search.  - Sob