Planning For Big Blue's Trip To Ouray

[85lebaront2]

Sometimes, even in the flatlands, you can't see the forest for the trees.

[Gary Lewis]

85lebaront2 wrote

Sometimes, even in the flatlands, you can't see the forest for the trees.

Boy, ain't that the truth! Oops, wasn't supposed to post yet!

The spreadsheet below holds promise. The row in green looks like what I want, although the row above it would be better than what I'm running and I have those rods. Anyway, I'm going to go looking for the 16-237 Carter rod. Will be such an easy change - pull the air cleaner, loosen two screws, slide the tabs out of the way, and remove the rods and pistons. Change the rods and reverse the above procedure.

[Gary Lewis]

And, for the record, here's a chart I found on a Mopar site which shows the Carter rods and jets. This is a MUCH bigger set than Edelbrock is selling, which is why I couldn't use their calibration chart since it doesn't show combinations using these rods.

Bill says he has a number of rods and jets so will check to see what he has. Perhaps he has the ones I'm looking for. In any event, his idea of just changing the rods and not the jets will make things SO much easier! Thanks, Bill!!

EDIT: Mike's Carburetor Parts supplied this pdf, which is the same as the pic I shared, but MUCH better:

[Gary Lewis]

I put the carb back together, but not before checking the float levels.  They were high by ~1/16" so I set them where they should be.  And of course that leaned the AFR so I had to adjust the idle mix and idle stop, and it'll change things on the road as well so I'll have to check that out.

And, just to document things, I'm running .110" primary jets, #1455 rods (.074 x .042), and the orange springs which allow the piston to come up at 5" of vacuum.

Then I did some calling around looking for the .077 x .052 and .078 x .054 rods  Tried Mike's and found the largest rod they have in stock is a .075", which isn't big enough.  Called Allstate Carb and they have a pair of .076 x .052 in stock so I bought them as they are slightly better than the .076 x .054 rods I have on hand and should give proper AFR at 5700' for cruise and 7500' for power.

Then I called The Carburetor Shop and talked to John.  Or maybe I should say I listened to John.  He's like Bill in several ways.  First, they are the same age.  Second, he's forgotten more about carbs than I'll ever know.  Unfortunately he didn't have the rods I want, and while he could make them since he has Carter's original engineering drawings as well as their lab lathe, that would be a very expensive proposition and not worth doing for a 4-day stay in Colorado.

According to John, Carter rods don't necessarily work in an Edeljunk (his term) as Carter had 19 different rod profiles, meaning where the step is and how long the ramp of the step is.  That got me to wondering, and sure enough there is a difference.  Here's a shot of a Carter 16-691 (.076 x .055) rod vs an Edelbrock 1455 (.073 x .042) rod.  You can see that the step on the Carter starts a little bit farther down, meaning that the rod has to come out of the jet farther before enrichening the mix.




Also, John suggested that I not change rods but instead lower the float levels 1/16".  But that's not something I want to do as it is a lot more involved than swapping rods.  And, there is a much higher chance of error when doing so - like what I did today when I got the fast idle linkage on wrong.  

So I'm going to limit it to swapping rods.  And for those that don't know what that entails, once you pull the air cleaner you use a 1/4" socket to loosen the screw in the pic on the left, swivel the cover out of the way and the piston pops up.  Pull the piston out, pull the spring down that is circled in red on the right, and pull the rod out.  Put the new one in, and reverse the above procedure.  Including removing and reinstalling the air cleaner it might take 5 minutes.

[85lebaront2]

Now you understand why I suggested that. FWIW, lowering the float levels can give you hesitation as the throttles open far enough to transition to the main jets. If they wanted to make changing the float level easy then it would be externally adjustable like the ones you hate.

If you think some of the US carbs are strange, sometime you need to find a Solex 4A1, a shining example of what happens when Germans try to "improve" on an American design. Take everything bad about a Quadrajet and then modify the good points till they are bad.

[Gary Lewis]

I knew how easy it is to swap rods, but never realized that there are rods big enough to tame those .110 main jets for high altitudes.

Had a thought - how 'bout tinning the rods?  How much might that add to the diameter?  I do have multiples of some of the smaller rods so could experiment.

Bad parts of the QJet?  Like the leaky well plugs?

Speaking of QJets, John and I talked about them and TQuads.  He is a real fan of both.  But mainly he likes the Carter Competition Series carbs.  Had a high perf 390 in a '68 F100 and put two of them on with a non-progressive linkage.  But he took the innards from a Carter made for a Mercury and put it in these carbs.  Said you could stomp it in any gear but 4th and it wouldn't bog, and you couldn't feel the secondaries open.  (He sure reminded me of someone else that is now 75, had a high perf 390, etc, etc, etc.)

[Gary Lewis]

Still doing some packing for the trip.  I added my DVM/tach/dwell meter to the toolbox to aid in setting the idle mix and speed.  And, it will come in handy if we run into any electrical problems.  Was going to put in a vacuum gauge, but I have the one that David gave me on the steering column, so no need for another one.

As for the carb work, I'll need either that 1/4" socket or a T-15 Torx bit for the metering rod cover, so I was trying to figure out how to handle that when it hit me that I have a Ryobi set of 1/4" drive bits that seem to cover most applications I might ever come across.  But I was struggling to find a magnetic driver for them until I remembered a set that I used to have, and while the bits are long gone I still have the handle and the case.

So I worked through what bits are in the Ryobi set, which has multiples of everything, and pulled out the ones shown below:

T-6 through T-40

1/16" through 9/32

SQ1 through 3

PH0 through 3

Cabinet 4 through 12

Here they are in the box, and some of you might recognize the Brownell's driver.  And on the right is where I'm thinking I'll cut a piece out of the Ryobi kit and put it in the box.  And that will include those sockets from 1/4" to 1/2".

Anyone with a better idea?

[Gary Lewis]

Today I ordered the Coyote deflators: CED456, SET OF FOUR COYOTE AUTOMATIC TIRE DEFLATORS – RANGE 1 to 65 PSI.  On Amazon it doesn't show a price and when you click "Show All Vendors" it says $144.  So I searched for them and on the Coyote site it has them for $66.39 instead of $79.99 and shipping was only $4.75.

Not only that, these are the ones where you tell them what pressure you want them set to and they come that way from the factory.  I asked for them to be set to 15 psi.

[Nothing Special]

You'll like them!

And setting them yourself isn't hard, but it is a time consuming trial-and-error process.  So if you decide you need to change them it won't be a big deal, but you saved yourself a bunch of time getting ready for this trip!

[Gary Lewis]

Thanks, Bob!  I'm sure I'm going to like them.  And I'm really pleased with the price.

Do you think 15 psi is a good starting point for the DISCOVERER S/T MAXX - LT285/75R16 tires?  They are a Load Range E, so are pretty stiff in and of themselves.

[Nothing Special]

I think that's a good starting point.  I was running 15 psi in my 33/10.50-15 load range C tires on my Bronco until last year when I dropped to 12 psi.  And I ran 15 psi back when I had LT235/85-16E tires on a CJ5.

On the lightweight CJ5 15 psi in those tires was too much (those tires were just too much on their own), but I didn't know enough to know that until I got load range C tires on the Jeep.  They worked OK, but the ride was still pretty brutal.

On a truck that weighs close to twice what that Jeep weighed I think load range E tires will still be a bit more than would be ideal in some respects, but they'll be fine (and I certainly understand your desire to use what you have rather than throw money at it to get something that might be a little better).

Anyway, yes, it's a good starting place.  If you want to experiment you can drop a bit more and see if it rides any better, or if you notice that you need the front locker any less.  And you can do that experimentation either by just using a tire gage to let a bit more out, or by adjusting only one of the deflators rather than taking the time to do them all.

And this might be a good time to point out what would make you want to go higher or lower.  Lower is always better for ride quality and traction, and those are the things in short supply when rock crawling.  Higher means less time airing up (maybe not such an issue for you with your setup), less chance of losing a  bead, and better handling if you get a chance to drive at some higher speeds before airing up.  Oh, and also less chance of rim damage if you whack a rock at those higher speeds.  So you'll have to figure out what you do and what you want.  But 15 psi will be a good place to start doing that.

[Gary Lewis]

Thanks, Bob.  I appreciate the input.

If 15 psi is a good starting point it may be the ending point as well since I'm not sure how hard we are going to push things.  So if the ride is reasonable and the traction is adequate we may just stay with the original setting.

Which then brings up the question of what I should air back up to for short highway trips?  As you know, but for the other's sake, many of the Jeep roads around Ouray begin and/or end off CO 550, aka The Million Dollar Highway.  So it isn't unusual to take a trail and then have to get back on the highway for a stretch before getting to the next trail.  And since the highway is full of curves, some of which are very tight, how much air do I need?

I normally run at 35 psi, and had planned to take the tires back to that.  But obviously it'll be faster if I don't go back quite that high.  Might 30 be adequate for a few miles if we take it easy on the turns?

[Nothing Special]

First I wanted to apologize for only talking about rocks.  I guess some people go fourwheeling in sand, mud or snow as well!

Sand is also less air is better until you lose a bead.  And serious rock crawlers or sand runners run somewhere between 0 and 10 psi, depending on rig weight, tire size, actual conditions, etc.

Mud and snow I'm less sure of because there's so much variety in both of those.  Generally though people probably run a little higher pressures in those conditions unless either is bottomless and they're trying to float on top of it.


As to what to air back up to, all I can say is do what works for you.  You might be able to get by leaving it at 15 until you're done 'wheeling.  The issues with lower pressure are bad handling and possible tire damage from heat.  In Ouray I've left my tires at trail pressure and driven a little slower if I don't want to take the time to air up.  Or I've aired up to 25 or 30 (I also normally run 35 on the road) and then drive more normally.

[Gary Lewis]

Bob - Sorry, I meant to reply and somehow got sidetracked.  

And thanks.  We will probably air up to at least 25 if we are going very far, but that shouldn't take too long.  In fact, I might actually check to see how long it'll take using these that came in today.  




And the MyFAK came in today and fit right into the storage unit, as shown below:

[Gary Lewis]

Just had a chance to test both the deflaters as well as the compressor.  I put the Coyote deflators on and in ~5 minutes I was down to their settings.  I checked with my two gauges and one showed 14 and the other showed 13 on all four tires, so I'm guessing that Coyote's 15 psi setting is accurate and my gauges are off a bit.

Then I aired all four of them back up to 20 psi, which took 3 minutes and 15 seconds with the tank at 200 psi at the start.  Then I aired them on up to 25 psi, and that took another 2 minutes and 35 seconds.  In other words, it looks like it takes about 3 minutes for each 5 psi on all four tires at that low range, although as I think about it that first "5 psi" injection was probably from 15 to 21 psi since my gauge was reading 1 psi lower than Coyote's setting.

But, I discovered that kneeling beside the tire and holding the inflator w/a gauge on wasn't all that much fun.  So I put the clamp-on inflator on when I took them back up to 35 psi, and that is a whole lot better.

Given that, I'm thinking at the end of the trail I'll give each tire a 2 minute shot of air.  My math says that should bring the tires up to 28ish psi, which should be plenty for running around on the highway.  And I won't have to even check the pressures but just time the shot.

Is that reasonable?

And, by the way, this is what the right front looked like at 15 psi.  It is a bit lower than I expected, but I guess it is ok?

[grumpin]

That’s impressive to me! Not as long as I thought it would take to air up.

Those deflators are cool.

A couple minutes sound good to me and you’ll see it too.

BTW, nice locking hubs!

[Gary Lewis]

Thanks, Dane.  Yes, it was less time than I thought as well.  

Doing a bit more math, it took 350 seconds to air 4 tires up 11 psi (14 - 25).  So it took 87.5 seconds per tire.  And dividing that by 11 psi gives 7.95 seconds/psi.

Dividing the two minutes by 8 gives an increase of 15 psi for a 2 minute blast.  And to go from 15 psi to 35 psi would take just 2 minutes and 40 seconds.  

Obviously this is all back-of-the-envelope math, but the system works really well.  I think I'm happy!  

As for the hubs, yes they are nice.  But they seem to be kind of scarce.  

[Nothing Special]

Yeah, a clamp-on chuck is a necessity, for the same reason the deflators are.  I had a hard time squatting down to deflate tires when I was 30.  I love my Coyote deflators!

And I'm jealous of your compressor!  It takes me a LOT longer to air up.

And that tire looks pretty good to me.  You could probably get by with a little more air, but you'd be OK with less too.  Like I said before, less air is better for ride and traction, the two things you'll be waning more of most of the time on rough trails.  More air is better for tire life and handling, which don't matter so much on most trails.  Losing a bead is the other downside to low pressure, and I don't think you'll be close to that at 15 psi.

[Gary Lewis]

Thanks, Bob.  It is comforting to know that the tire looks about "right" for the plans we have.

As for the compressor, it really works.  I didn't check on the pressure, but since the compressor cycled while I was airing the tires up I'm guessing that the pressure was between 155 and 200, and that can move a lot of air.  However, as I think about it I have the regulator set at 90.  I wonder if it would fill faster at full tank pressure?

[ArdWrknTrk]

Tires would definitely fill faster with higher pressure.
But the Schrader valve in the stem is really what's limiting flow.
That's why many will pull the valves when trying to seat a bead