AFB metering rods

[rocketman]

Looking for 4 16-124 afb metering rods for 3361-2 carb setup. I'm putting together a 409 for my 62 Belair Sport Coupe to run in the Pure Stock Muscle Car Drag races here in Michigan. The Carb Shop wants $280 to machine 4 rods, that quite a bit more than I can spend. Ronnie Russell has some rods that are close to the stock ones, and jets I'll need in the .070-.077 range. I'd like to try some stock rods if possible. I posted in the wanted ads too. Thanks Dave

[Ronnie Russell]

Dave, $280 ?????? That's the funniest thing I've heard in a while. If you can't find the stock rods ( .069x.0635 ) I have the .071x.058 s . As explained earlier, a hair leaner than stock on cruise mode and 1 to 1 1/2 step richer in high-speed mode. You would never know the differance. In fact, they should be a better rod for your application. That would be with a .101 jet. Price is 41 cent stamp.

[jim_ss409]

I'm sure the factory rods would be CLOSE to perfect but it's almost certain that some other rod-jet combo would be even better. The fuel we get today is different and if you do any intake manifold mods or run an open spacer that will also throw things off a bit. The edelbrock instruction manual describes how to fine tune the air-fuel mixture. You can read it on line here... http://www.edelbrock.com/automotive_new/mc/carbs_acc/pdf/carb_owners_manual.pdf
Maybe someone will have the stock rods but if not just get something close then try going richer and leaner untill you hit the right combo.
By the way, there was a bone stock 63 Impala that ran really well in the Pure Stock Muscle Car Drags a few years ago.
Good luck.

[Ronnie Russell]

Jim, I'm not sure if the Edelbrock charts pertain to a 3361 Carter. My reason for saying that is according to my hand written notes ( not sure they are correct ) the 3361 uses .101 primary jet with .069x.063 rod and .063 secondary jet. When compared to 1404 ( 500cfm) Edelbrock, .086 primary jet with .065x.052 rod and .095 secondary jet. The 1405 (600cfm) uses .100 primary jet with .070x.047 rod and .095 secondary jet. So the 3361 is similar to the 1405 on the primaries but much smaller in the secondaries. It would appear the 3361 is of a different design to use those jets. Over the years I have seen the 3361 rated from 500cfm to 625 cfm. As I've said before, I have never raced 3361-3362, but thousands have. Maybe Aubrey or gearhead can contribute. But I don't see how the Edelbrock chart can be used with the 3361-2. I do like to learn so maybe someone will enlighten me.

[gearhead409]

when Edelbrock came out with their version of the AFB they made alot of changes in it. when it comes to jetting the Carter AFB verses the Edelbrock, they're two differant animals.

[jim_ss409]

I see what you mean Ronnie. I don't really use the charts on the Carter carbs but I do follow the general advise given about getting a proper fuel-air mixture. In my case, tunnel ram or stock manifold with open spacers, I've found that I have to jet richer. So I just work off of the stock setting then go with smaller rods and larger jets until I get it right. I try to balance things out so that I go an equal amount richer on the primarys and secondaries but there is some estimating involved. But after looking at the Edelbrock chart I see that they don't make a metering rod that's very close to the .069/.063 Carter. The closest thing Edelbrock seems to have is a .065/.057 That's not too far off but it might require a .100 or .098 jet to work out to the right flow.

Rocketman, I've got a pretty good sized pile of rods. I'll check tomorrow to see if I happen to have the exact size you need.

[dq409]

I have both the Edelbroke and Carter racing re-jet kits and it seems the difference between the two is only the combinations of the jets and rods.
That does sound confusing but what they did is one uses a larger jet and larger rod then the other to achieve the same jetting.

Lets see,,, how to make that clearer,,:scratch
it makes the same sized jet hole,,,,
Just different numbers,,,

You can get the Carter Calibration kit has a ton more jets then the Edelbroke box.

Try these guys,,,http://www.carburetion.com/Carter4.htm

[Ronnie Russell]

To avoid further confusion,,,, The Carter 9000 series carb is the same as the Edelbrock carb. I have examined both many times and can find almost no differance. Jet and rod sizes are the same or almost the same . The Edelbrock charts are a great tool to tune both the Carter 9000 and the Edelbrock. As the distinguished gentleman from Ohio said ( can you tell I've been watching too much immigration debates?? ) the Edelbrock and Carter 9000 series carb are different designs of the old style AFB so the charts dont work for the earlier AFBs.

[jim_ss409]

I have both the Edelbroke and Carter racing re-jet kits and it seems the difference between the two is only the combinations of the jets and rods.
That does sound confusing but what they did is one uses a larger jet and larger rod then the other to achieve the same jetting.

Lets see,,, how to make that clearer,,:scratch
it makes the same sized jet hole,,,,
Just different numbers,,,

You can get the Carter Calibration kit has a ton more jets then the Edelbroke box.

Try these guys,,,http://www.carburetion.com/Carter4.htm


I understand what you mean. (now that's scary) It doesn't really matter what combination you use as long as the hole the fuel flows through ends up being the right size. But it does get harder to estimate the total flow area if you stray too far from the stock setup. One thing I have noticed is that there isn't a lot of difference between the power step and the economy step on the factory rods. That seems to be a good thing because I've noticed that I once I get the power mode right I'm a little lean in the cruise mode with the wider stepped rods.

[jim_ss409]

Rocketman, I checked and I don't have any of the stock 16-124 .069 x .0635 rods. Maybe someone else does.

If you can't locate any here's a quote from Curt Harvey, a very experienced W engine builder...
"With stock carbs I usually use .100 primary and .074 secondary jets with .073 x .060 rods, and if it's rich I go to .098 primaries"

But wait,,, I just looked and I don't see .073 x .060 rods listed in either the Carter or the Edelbrock listings so they might be just as hard to come by as the stock rods.:cuss

If worst comes to worst, you'd still be very close with an Edelbrock .065 x .057 rod with a .100 jet and if that's too rich go to a .098 jet.

[Ronnie Russell]

Or maybe the .071x.058 s I have suggested for 41 cents :rofl :rofl

[409z28]

Here use the math to measure rich or lean.
Pick a jet .092 divide by 2 = .046 then x .046 = xxxxxxxxxxx
then X by PI 3.1415927, that = area of jet
The do the m-rod say .069 div by 2= .0345 then x .0345= xxxxxxx
then X by PI 3.1415927 that = area of rod subtract the two and it gives xxxxxxxxx

Now do the same to a different combination of jet- m-rod combo... the larger the # the richer you are. This way you can FINE tune that thing: to the cats whisker. Paid off for me when I raced Stock and SS stock. :)

[jim_ss409]

409z28, That's a great formula!:deal

I tried the stock .101 jet and .0635 rod and came up with .0048449
Then I tried a .098 jet with a .058 rod and came up with .0049009
I'd bet that rocketman could find a combo of jets and rods that would be even closer with a bit of calculating.

[409z28]

Jim,, back in my days we didnt have computers or Jeg's or Summit. We had to THINK and use our brains a little. Hope this helps for those that need that little x-tra. Mike:) :)

[rocketman]

Thanks everyone, now I see how this works should have no problem finding a combination with the edelbrock calibration kits and parts. Heck of a lot cheaper than $280 for 4 rods. Thanks again. Dave

[Ronnie Russell]

This has been an entertaining discussion . Mikes formula is fun to experiment with. rocketman stated in an earlier post that he wanted the .069x .0635 rods to use with .104 jets along with .074 secondary jets so as to duplicate a setup he found in an article from the way racers set em up " way back then". I suppost that is why he wants the exact .069x.0635 rods. Using Mikes formula , I came up with .104 jet with .0635 rod = .00533 .101 jet with .058 rod = .00537 Probably gonna take some sandpaper on a rod to get closer. I reckon a .071x .058 rod might just work. I mailed my last 4 to a buddy in New York today. They are a common size so they should not be difficult to find.

[409dog]

For the mathematically lazy. Use this chart.

[acr3]

Remember that the original Carter AFB, made from 1957 to mid-1980's (when Federal-Mogul took it over) had a domed plate/cover, & 3 step (longer) metering rod than the Fed.-Mogul, Weber or Edelbrock AFB's. Those original 3 step rods are rare & expensive! You can convert to the newer 2 step (shorter) Fed-Mog. or Eddy rods but you have to use the newer jets & flat covering plate, or fill in the domed plate w/JB Weld,etc. ;)

[fatride]

I thought the three step rod was introduced in the early 70s when the heavy RVs were becoming popular? Most of the early AFBs I have worked on had a two step rod. :dunno

[Ronnie Russell]

Affirmative Ray,,,, The vast majority of early AFBs are two step rods. There is such a thing as a three step old style AFB , however I have never seen one. The early AVS carbs were three step, but not the same as AFB.

[jim_ss409]

409dog, Great chart!:deal

I printed it and I'll keep a copy with my carb jetting stuff.