Sec Hanger Height

[von]

  I read in another place that the specific hanger letter doesn't matter as longer as the hanger height is 41/64" from the top of the airhorn to the metering rod holes in the hanger (doesn't say whether top of hole or center), when the air flap is open and hanger is raised. Can anyone confirm or dispel that?

[omaha]

I do not agree with that at all. Its a tuning tool that can have an effect on power. Everything else is the same except the hanger and the metering rod. the jet diameter is the same in all q-jets and it is non-removable. Yeah you can mess with the poe and the sec. well feed hole but that is just for the transition stage from prim. to sec. Different hangers will locate the TAPERED (imporant) metering rod at different heights in the jet hole. This has the same function as changing jet size. The cam that lifts the rods are the same also.  edelbrock sells different hangers. 4 or 5 I think.

[von]

I understand what you're saying and agree in general. I have a list of different hangers and their specs. But it seems there should be a starting point for height of the rod holes, at least certain heights for certain rods (long, med, or short at least). There could be variances due to cam wear, hangers being bent, etc. I've heard an NHRA racer (Michael Beachy) makes a hanger bending tool for sale. I'm thinking, why have an assortment of hangers when they can be adjusted (bent) so easily. Maybe a range of hole heights from richer to leaner? Or 3 ranges for long, med, short rods?

[omaha]

I guess if it were me I would start with one of Cliff's recipe's that would match up with the engine combination being used. Then, if changes were thought to be needed, they could be done either on the car and/or without removing the top from the carb. ( one of the few easy things to do on a Q-jet). The secondary rods and hanger are acessible from the outside of the carb. So then, hangers, rods and opening rate. Those are the BIG three elements used to tune the secondaries. The next part is the drag strip. Have fun!!

[von]

  One of the reasons for asking is that when I first installed my old "F" hanger (which agrees with Cliff's second recipe), it was bent so far off that one of the the metering rods was coming up so high it was hanging up on the oriface in the main body. I first bent the hanger to conform to the 41/64" installed dimension but in measuring the hanger itself it was even lower than a "V" rod spec. So I bent it back to it's original "F" spec of .540  from the centerline of the hole to the underside of the hanger mounting surface. The spec is in an old version of the Doug Roe book I have. I believe the "F" rod agrees with the second recipe which calls for "G" or higher. I'd still like to hear Cliff's take on this.

[Cliff Ruggles]

The hanger height controls the fattest portion of the rod in the jet (orifice) at the initial onset of the secondaries.  Since the secondary cam raises all hangers the same amount, it also controls how much of the tip is in the jet at full lift.  These facts are pretty obvious.  What isn't obvious, is that different metering rods have different dimensions for their entire length, and produce different fuel curves as they lift out of the jets.

The length of the tips, and diameter, combined with how far they are out of the jets, will have final control of the fuel flow once they reach maximum height.

It is actually possible to go to a smaller tip rod, and lean up the fuel curve vs a longer tip rod that exposes more of the jet opening (based soley on hanger height).

For most applications, it is best to start out with a lower hanger (higher letter).  I made a gauge years ago from a peice of flat stock, by drilling different holes in it, corresponding to the "B" hanger and up to "P".   I don't search in vane these days for various different hangers, I just bent the arms to get them even and where I want them on the scale.

I use DA or CE metering rods for most builds, and set the hanger height low for initial testing, then bend the hanger if/as needed for best results during a running test.....Cliff

[von]

I guess I'm still confused as to hanger height versus hanger letter code. Either that or the chart I saw in a Doug Roe book is wrong. I'm assuming by "higher letter" you mean a D is higher than an F, correct? Or the other way around?  Per the chart I saw, a D hanger has a centerline of rod hole to bottom of hanger attaching flange spec dimension of .530 and an F hanger is .540. That would mean the F hanger would put the rods lower into the oriface at the same air valve opening and therefore tend to be leaner with the same rods as a D hanger, correct? In your book second recipe you recommend a G or higher hanger. I took it to mean G,F,E, etc. Is that correct?

[omaha]

I think you are correct. Just like the B hanger is .520
                                                  the P hanger is .590
                                          I could see the confusement.
    since you are measuring from the top down, it actually means that the rods are hung higher in comparison 
                                         to the jet with the B hanger at .520 than the P hanger at .590.                   
                                                                                                                                                                                                            [In the alphabet you could say that the P letter is higher than the B letter.]                             
                                        Not the case with the rod hanger letter designations.                                               
                            The lower letters in the alphabet actually HANG the rods HIGHER in the jets.
             If you look at the summit site, it lists the hangers they sell {seperately I guess} as B, G, K, and P.
              Where can other hangers be obtained?  Would  a person actually need more of a selection than these for fine tuning?  I wouldn't think so seeing as you can bend them to suit your needs. I know rods a able to be modified also.    This is all very enlightening info as I have not put much research into the secondary side yet.

[von]

How can the lower letters in the alphabet hang the rods higher in the jet then higher letters when the dimension is more from the hole to the mounting surface? The greater dimension places the hole and therefore the rod closer to the jet.

[Cliff Ruggles]

Confusing stuff, isn't it?

I really don't pay much attention to hanger height here.  Decades ago I made a gauge from a peice of flat steel the same width as the part in the q-jet that holds the hanger.

Using a "B" and then an "P" hanger, I drilled a small hole at each point thru the flat stock.  I use this to compare different hangers, and custom bend them if/as needed. 

It's interesting to find that most factory hangers to NOT hold the rods exactly even, being a mass produced part, and often they get bent during rebulding, especially when the rebuilder bolts down the airhorn with the hanger and rods still in it!

What I do pay close attention to is the metering rod.  Rods with rich tapers and long tip delivery more fuel everyplace than those with fat sections and short fat tips.  As a general rule of thumb, rich tapered rods require a lower height in the jets, all else being equal.  Also, the better we set up the POE system, as mentioned in our book, the lower the hanger will be required.......Cliff

[von]

I guess I'd still like to know what the definition is of "G or higher", per the second recipe in your book. Would an F fit that description or would it be an H, all else aside?

[kamcoman]

As I understand the response from Cliff about "higher letter = lower hanger" I am assuming that the letter A is considered letter #1 in the alphabet, therefore the "lowest" letter.  This would also equate to the highest hanger (rods held higher in the secondary metering holes).  Therefore, when Cliff says a hanger F, or higher in his book, I think he means F, or G, H, I, and so on for higher letter (Z=#26).

If this assumption is wrong, please advise.  Von and I are trying to figure this out.  In Von's last question, H is higher than G as far as letters go, if my assumption is correct.

Keith

[Toronado]

Well sounds like you could
get some different rods and test them out,
on the hanger than bend the hanger
if it needs further adjustment. No matter
what, you need to test them out at the track
to measure actual difference, the numbers
never lie, just go with which size gets you down the track the fastest and thats the size you need. I do get trying to follow the recipe in the
book, but you still have to test it out even if its the exact rod size you need.

[Cliff Ruggles]

Something to keep in mind here, more important than hanger height, is that comparing metering rods on the dyno and/or at the track can be very miss-leading.

Unless all of your metering rods are cut from the same core, the results can be all over the place.

Quite a few of our customers have us custom machine sets of rods for them from the same cores.  This way they do NOT have to change hangers with each set of rods tested for direct comparisons.

What happens in actual use, is that you can go from a small diameter long tipped rod, AX for example, to a short tipped rod with a much smaller tip, and actually lean up the fuel curve.  This happens due to the fuels inability to flow around the fatter rod section into he hole in the casting floor as effectively.

Bottom line here, if you want to see precise changes when making metering rod changes, use the same metering rods with the tips custom machined to different diameters.  Then you can test them on the same hanger back to back, change hangers and test them again, etc, with accurate results.....Cliff