Mileage Quest 2011!

[Montana71-F100]

I think I found the answer at: http://www.aa1car.com/library/carburetor.htm

Too rich: Plugs have heavy black, sooty carbon deposits on the electrodes.
Too lean: The ceramic insulator around the center electrode may be yellowish or blistered in appearance.
An overly lean air/fuel mixture can cause engine-damaging preignition and detonation.

[Montana71-F100]

Thanks! This has been a great education for me. I had never heard of a wideband tuner. It sounds like a great tool. I don't want to spring for one right now so I'll try a 50 and if I'm getting pinging at 36 degrees BTDC I'll know to try a 51.

[woods]

Try with the timing high first. Do one thing at a time, that way you know where you're at. I am guilty of doing too much at once. I'll fix a bunch of potential problems at once, the problem will go away, but I never knew just exactly what it was. Change the jets, see if it pings, if it does back off the timing a bit and see if you can get it to stop. If it stops around 36 38 or 40 and runs good, let it be.

[Montana71-F100]

That sounds like a good strategy. I'll do that.
Thanks.

[Bumpside Collector]

I tried out the manifold vac to the dizzy idea and man was I surprised! I don't know if it helped the mileage but it sure woke the engine up. The throttle response is much better and it feel more powerful throughout the range. I'm a believer!

[cdeal28078]

Not addressing the posters questions but.... I did go from ported to manifold vacuum the other day. I have not driven the truck without the trailer and mower on the back yet but it sure feels more responsive if that could be possible. It was already pretty dang responsive with a very mild 460 in it. I backed off the vacuum advance two turns at 1st but put that back in today and still no spark knock and it felt even better. I need to do a complete timing curve on this thing again as it has been a while. I am not having the idle problems I've had in the past when I tried this. I think because I have my secondaries adjusted pretty much closed. I need to back the idle down as it is too high caused by the added timing.
Now I read somewhere that I need to adjust my A/F again right WOODS? I havn't messed with this 1850 Holley in several years so it could use some attention I figure anyway. Don't know why people say a Holley has to be adjusted all of the time as this one sure stay where I put it
Thanks for the help and the advice to try this again. Might get me a couple miles more er gallon
clint

[woods]

Well...advancing your timing does make your air fuel ratio leaner, it's burning more of it. But you're not "really" advancing your overall timing by going to manifold vacuum (as you know).
It will run more advance at idle and at light cruise, where is is okay (even preferable) to run as lean as you can without any ill effects, such as stumbles or getting hot. It usually won't change the ratio enough in that area to cause any issues and if it does, it will show itself as a slight stumble or jerk when the power valve opens. If you don't have any of that and have not advanced your total timing, then leave it alone (if you like the way it runs).
Now, if you start putting in more total advance and find that it keeps building more power with more advance (like on a dyno) you should keep adding a little fuel until you reach a spot where power starts dropping off and then back up.

The only reason Holley sets their secondary plates just a tiny bit open on your 1850 is so that they do not stick closed. Not all of them stick, really, very few of them stick. I have seen a few that when warm, they can be just a little sticky if seated all the way, but 9 times out of 10, they will be fine.

I think the whole "you need to fiddle with Holleys all the time" thing is just something passed down. You know, one person hears it, then tells someone else and so on until it becomes something that is repeated as fact. A carb does not "go out of tune" once it's in tune. A mechanical failure of it can happen, other engine problems can happen, a chunk of debris in the carb can happen, but if everything is right...it's not going to change size on you or jetting on you, it's just a mechanical device. If set right once, it's not going to go out of tune.
Now tuning at the track for different weather and altitude conditions, that's a whole other deal. But, for a pickup you're just scooting around in, a holley will serve you trouble free for a very long time. Heck, I'm using the same carb on my motor (holley) that I have had in my possession since the 80's. It has had one rebuilt kit put in it and that was from me letting it sit too long on a shelf.

[cdeal28078]

Good advice. I need to go over the carb pretty soon anyway since the other day I stood on the gas for the 1st time in a while and I didn't hear the secondaries open. They might be stuck. Had a little popping and stumble happen and backed off.
My tail pipes are pretty dark so I need to lean it out anyway. I like to have at least a dark gray tail pipe and mine are black. I think I need to go to a smaller main jet size.
I'll also do a complete advance curve on it since I really don't know where everything is anymore. Used to run 18 initial but I think I backed it down a little a while back
Thanks Woods
clint

[woods]

You should not feel the secondarys come in if you have the right spring, but they may be sticky. Try to open them by hand and see if you feel a slight catch right off of their seat. If so, you may need to raise them off their seat a little to get them to open (or pull it off and adjust the plates a bit).
Do you remember what powervalve your carb has?

[OldBlue67]

Awesome thread! I'd be interested to see what kind of change, if any you get from higher octane gas or even an octane boost additive. I had a friend with a 70 f100 that swore by high octane gas and would add octane boost too for better milage. This was a long while ago so I don't remember his trucks stats or what kind of improvement he claimed, but it would be interesting to try out.

It reminds me of a slightly OT story:
I once dated a guy who was into autocross. One time I ran out of gas while heading over to his place in Blue. He said he had a spare can of gas and would bring it out to me, well it turns out his "spare gas" was 110 octane leaded racing fuel! Man, Blue purred like a kitten all the way to town! I can't attest for the gas milage but the engine had never run so well

[OldBlue67]

Interesting! Well that works out well 'cause that's just the kind of gas I can afford

[woods]

Ya, no kidding.

[BobbyFord]

So what happened with regard to the MPG's on the original poster's truck? About the ONLY thing you can do to improve mileage on these things is to lower the average running RPM via gear change or tire diameter. What was the outcome in the quest for better MPG's?
I know what to do to get worse MPG's if anyone's interested

[fomocoguy]

So what happened with regard to the MPG's on the original poster's truck? About the ONLY thing you can do to improve mileage on these things is to lower the average running RPM via gear change or tire diameter. What was the outcome in the quest for better MPG's?
I know what to do to get worse MPG's if anyone's interested

Back on page 7 I made my last mileage run and it came out to 13.2 mpg. I've been very busy so I haven't made a run since I advanced the timing 2 more degrees and switched over to full manifold vacuum advance. I promise I'll try and get a run in over the next few days and we'll see where she is. I'm far from finished, but all in all I think 13 ain't too bad for a 4x4 crew with 4.10's. It's better than my buddies 04 V10 F250 crew 4x4!

[BobbyFord]

So what happened with regard to the MPG's on the original poster's truck? About the ONLY thing you can do to improve mileage on these things is to lower the average running RPM via gear change or tire diameter. What was the outcome in the quest for better MPG's?
I know what to do to get worse MPG's if anyone's interested

Back on page 7 I made my last mileage run and it came out to 13.2 mpg. I've been very busy so I haven't made a run since I advanced the timing 2 more degrees and switched over to full manifold vacuum advance. I promise I'll try and get a run in over the next few days and we'll see where she is. I'm far from finished, but all in all I think 13 ain't too bad for a 4x4 crew with 4.10's. It's better than my buddies 04 V10 F250 crew 4x4!

I agree that's pretty good mileage for a 4.10, 4X4.