Mileage Quest 2011!

[fomocoguy]

So I checked today and whomever was the first to suggest that the fast idle screw on the choke may have been interfering wins the debate. I should have checked it first thing but I didn't even think about it. I adjusted it, so she's purring like a kitten at 650ish rpm.

I just checked back and it was woods. Nice catch!

[woods]

Cool...now all I have to do is become mildy sane and the whole life thing will be a snap.

[Montana71-F100]

Following up a little with the timing talk....

I feel that many folks underestimate the importance of proper timing in a vehicle. I mean, most know that it's important that it be set correctly for the engine to run, they set it at whatever the initial timing recommended is at idle and call it good. Well...it will run that way and will normally run good enough for you to think there is nothing wrong with it, but doing that can leave a lot of power and drivability on the table.

Total timing and at what rpm it comes in at are very important in making your engine run like it should. A lot of people are shocked at how well something runs and how much power it has when the distributor is set up properly. The easy thing is to take out the distributor and bring it to a guy like me with a machine to set up your advance curve...but, you won't really learn anything that way and you can do it yourself with a little trial and error.

Lets start with total timing. Forget about the vacuum advance talked about earlier, it has no bearing on total timing when your in the throttle hard. Here is the problem with a lot of distributors...when you set it to the total advance you want, many times the initial timing is too low. So it's a bit soggy down low, but screams to life once you built up some rpm. This is because the distributor has too much mechanical advance built into it. In example...lets say your distributor has a total mechanical advance of 36 degrees in it and you want to run 36 degrees total timing. Well, that means you will have to set your initial timing (at idle) at 0. This leaves a lot to be desired down low but runs great up high. You can put more initial timing in which will improve your bottom end power, but moves your total advance up way too high.

Well, there is an answer for this. Many of our distributors have a plate under the breaker plate. You may not have this, but many do.

dist15.jpg

You will notice in the picture that one side of this plate says 10 and the other says 15. This is what limits the amount of mechanical advance in your distributor. Since the distributor turns half the speed of the crankshaft, you double those numbers, so 10 will be 20 degrees of total advance and 15 will be 30. Most of the time, it's set on the higher one. By the way, there are a lot of different plates, some are 13 and 18 some are 12 and 20...you get the idea. If you turn it around so you're on the lower number, you can run more initial advance (for good power down low) and not go past the full amount of total timing you want. On this one take for instance, you would flip it over to the 10 side, this will give you 20 of degrees available in the distributor. Lets say you want to hit 36 total advance now. You would set your initial at 16, total would be 36. Good power down low and up high.

To flip this around, there is a small clip in the top (you will see it), you can get it off with needle nose or a small flat screwdriver. Now, since you turned it around, your rotor will be pointing 180 degrees off. The best way to deal with this is just to lift your distributor up a little, turn it back where it was and set it back in place. Or, you could be like a buddy of mine and just switch the plug wires around (because his distributor is stuck and he does not want to mess with it).

Anyway, doing this makes a huge difference in the way the car or truck will run and drive.

Now...they also make a spring kit so you can adjust what rpm your mechanical advance starts. I cannot give you an answer as to what rpm your truck should be at full advance, because it will be different from engine to engine, vehicle to vehicle. Have it come in as early as you can and not ping is the only suggestion I can give you. Up to you to find out where that is.

Once you have your distributor all tuned to your engine/truck and driving habits, you will be VERY glad you did. The difference is tremendous.

I really appreciate all of the input on this thread. I don't know anything about timing curves. I switched from ported to manifold vacuum and made the 180 degree switch in my distributor and put some lighter springs in. The package says they're not legal for street use but I'll take my chances.

It's a 71 with a stock 360 and electronic ignition. I removed the vacuum line and plugged it. My tach only goes to 2000 RPM. These are the results:

RPM /degrees BTDC
650/16

2000/46

Do these numbers look O.K.?

Thanks

[woods]

46 is pretty darn high...what number did your advance plate have on it, specificly the one you switched to? 15? Your avdvance is comming in good and working well. Have you driven it like this with everything hooked up? If it pings, I have another little trick you can use to reel in your total advance a bit.

[Montana71-F100]

46 is pretty darn high...what number did your advance plate have on it, specificly the one you switched to? 15? Your avdvance is comming in good and working well. Have you driven it like this with everything hooked up? If it pings, I have another little trick you can use to reel in your total advance a bit.

I was more intent on figuring out how to switch it than remembering the numbers. I think they were 18 and 21. I remember being surprised that the numbers were close together. I know they weren't 10 and 15. It may be a good idea for me to take it apart and double check.

I just took it for a drive for a few miles and up a hill at about 55 mph then slowing down as I went up and didn't notice any pinging. There's a fair amount of wind noise so I may not have heard it if it was.

Thanks for your input

[woods]

Yeah, some of the plates are high on both sides. A small pice of rubber tubing slide over the stop will limit how much total is avalible in such a case. If it pings, you will hear it (unless you have no exhaust). How did it run over all? Did it feel "jerky" any?

[Montana71-F100]

Yeah, some of the plates are high on both sides. A small pice of rubber tubing slide over the stop will limit how much total is avalible in such a case. If it pings, you will hear it (unless you have no exhaust). How did it run over all? Did it feel "jerky" any?

Thanks woods, It ran fine. Not jerky. How much advance should I limit it to? Is 16 BTDC initial timing too much?

[woods]

No, 16 is fine as long as you have no issue starting it. I run near 16 on my own truck, but I have an aftermarket starter that spins it over like there is no spark plugs in it. I would have really thought that 46 total would be a bit high, but if it runs good, does not ping and starts good when warm, then you're fine. Normally speaking, 38 to 40 is close to the limit for total mechanical advance on many FE's, but is most certainly not written in stone. With that change and no pre-ignition...your truck should feel more responsive when taking off and should start easier when cold...does it?

[Montana71-F100]

I just took it for a test drive. It started very easily cold and it is more responsive when taking off. I drove it out of town on a gravel road and up a fairly steep hill at about 35 mph in 4th gear. I put the peddle to the floor and it accelerated without pinging. When I got home, I shut it off and started it again to see how it started when warm and it fired right up.

I'll look forward to seeing the difference in the mpg. I'll let you know what I find out. It will be a while. I usually walk or ride my bike to work on warm days (about 3 blocks) and when I drive, its in town at 25 mph or under. I don't get on the highway with it very often unless I need to haul something because our van gets better mileage.

I have read about what you suggested about changing the distributor but didn't have the confidence to try it. It makes me wonder why the Ford engineers didn't come up with the idea. You'd think they'd do anything to be better than the competition.

Thanks for all of the help. It's nice to know it's running as well as it can.

[woods]

It will get better mileage in stop and go driving like you're doing for sure.
It was the time really...most engineers know what works, but it was not a free for all in these years, they still had to comply with certain rules (which is why your distributor springs are frowned upon). I love the FE engine to death...but it was not really a very efficient burner due to a lot of things. Chamber design, quench area (or lack of)...well, lots of stuff. You could make it run really great, or abide by the rules, not both given the technology at the time. So their hands were tied if they did not want to change the general lay out of the FE.

[Montana71-F100]

That's encouraging about the improved mileage with my stop and go driving. I appreciate the explanation of why the engineers did what they did. It makes sense.

I wonder if my elevation (about 5000 feet) has something to do with the ability to get by with more advanced timing.

Thanks!

[woods]

That's encouraging about the improved mileage with my stop and go driving. I appreciate the explanation of why the engineers did what they did. It makes sense.

I wonder if my elevation (about 5000 feet) has something to do with the ability to get by with more advanced timing.

Thanks!

It absolutely does. I did not know you were that high. Your engine is running on the rich side of things (due to less air). I would bet that you could safely drop a few jet sizes. I'm not sure what you have in there for jets now, but at that elevation you would probably run better with two to three sized smaller (and get better mileage). of course, if you lean it out a little bit, you will have to limit your amount of total timing, because then it will ping. I would give you a ballpark of three sizes lower on jets, keep your initial timing at 16, but knock total down to about 36.
This will make it run nice up there, a bit more crisp on acceleration and better mileage. Figure out what jets you have in there now and I can give you a more solid answer as to the size you should look for.

[Montana71-F100]

That sounds great! I put in a carburetor kit a few years ago and the jets seemed to be welded in place. I was worried about ruining the slots for the screwdriver so I gave up on taking them out. I'll give it another try when I have a little time.

The more I think about it, I live in a small town (pop 400) so the parts store probably won't have the right size jets in stock so I'll probably have to order them. It may be better to order the correct size and have them on hand so I can replace them when I take the original jets out. The carburetor is an Autolite 2100-D 2V. What size do I need?

I just did a search and found the elevation is actually 4324 ft.

Thanks!

[woods]

I would say 50 or 51 would be a good size for your engine, truck and altitude. Keep in mind that me saying that does not make it a sure bet...but it's a really good starting point...or it may just work perfect. I have seen the same engine in the same type of vehicle, with the same carb need different jets than the other one, but usually not by a whole bunch.

[Montana71-F100]

Thanks. What are things I would notice if I have the wrong size?