Rod difference between automatic and manual transmissions.

[MRSOFTE]

I have a 7028210 on my 68 325HP 396. The specs call for 71 jets and 49 rods which it has as the car did come equipped from the factory with a powerglide. But looking at a Rochester chart I see that a 7028211 which would be for a manual trans car, the specs call for 71 jets and 45 size rods. Assuming that chart is correct....why the difference?
Thx.

[Ethan1]

I have a 7028210 on my 68 325HP 396. The specs call for 71 jets and 49 rods which it has as the car did come equipped from the factory with a powerglide. But looking at a Rochester chart I see that a 7028211 which would be for a manual trans car, the specs call for 71 jets and 45 size rods. Assuming that chart is correct....why the difference?
Thx.

 Remember, the differences between A/T and M/T Qjets were the jetting. So, that would probably correlate to the metering rods as well. M/T Qjets were ran leaner than A/T Qjets. This was necessary for the A/T, to compensate for fluid loss.

[MRSOFTE]

Ethan
Thx for your time.  But I'm not exactly sure what you mean by fluid loss? The Rochester list I saw (posted by Lars)
shows no jetting change between the two. That stays at 71. Its only a difference in the rod size.  I did swap in a manual trans on to my Chevelle last year. But never thought there might be an "internal" difference between the two carbs.
Just an external one on the accelerator cable side for the trans kick down cable/linkage pin thing.
However, interestingly. Just after I posted the question I was rooting around in the garage, and find a set of 45 rods.
So after installing them I head out. And the absolute first thing I notice, is there is no more deceleration burble. It was minor at best before and not a real concern. I also had a "hardly noticeable" soft spot when pressing the throttle at around 3000 RPM. That is now apparently gone.
I have taken Cliffs suggestions he has stated in this forum to heart and resisted getting one of the wide band gizmos. And just concentrating on test and tune by feel. Besides its more fun that way! And in my opinion a lot less confusing.

[Ethan1]

 What I meant by fluid loss, was due to going through the torque converter. I didn't mean actually loosing fluid.

 As for the jetting, it all correlates together. Whether the jets are the same and metering rods are different or vice-versa, it is still the same.

[MRSOFTE]

Gotcha. But what exactly is going on in the engine for the factory to specify different rods sizes between carbs due to whether its automatic or manual behind the engine?

[Mudsport96]

My guess would be the way a manual " locked solid" Power transfer vs automatic (fluid coupled) minutely varying power transfer slightly higher rpms at the same speed for same gearing because of converter slip. 

[Ethan1]

My guess would be the way a manual " locked solid" Power transfer vs automatic (fluid coupled) minutely varying power transfer slightly higher rpms at the same speed for same gearing because of converter slip. 

 That would be my best guess as well. I don't think it has as much to do with the engine as it does with the transmission. I don't know why Rochester configured it that way, but they did.

[Ethan1]

 Also, keep in mind, the calibration settings on the M/T Qjet will have different size restrictors, air bleeds, etc., than the A/T Qjet. I should have said it is a calibration setting difference, not a jetting difference. Sorry for the confusion. I know someone who may have the answer to your question above or I can ask him for you. He usually doesn't like to be bothered by e-mail. I am an exception, LOL.

 EDIT: I just asked him the question. Let see if he knows the answer.

[MRSOFTE]

 I will have too get all the info I can off my 7028210, restrictor sizes and down tube size and so on. Unless that is all correct for my eng/trans combo I'll never get it all dialed in exactly right.
Ok thx again for your time.
Ill be back!

[Ethan1]

I will have too get all the info I can off my 7028210, restrictor sizes and down tube size and so on. Unless that is all correct for my eng/trans combo I'll never get it all dialed in exactly right.
Ok thx again for your time.
Ill be back!

 You're welcome, bud. Let us know what you find out, settings wise. I am not the person to talk to, to dial in your carburetor. Cliff, Frank, Carman, etc. are your best bet for that. I will let you know what, John, says whenever I here from him. Take care! Ethan

[MRSOFTE]

Copy that! 
Thx Ethan

[Ethan1]

Gotcha. But what exactly is going on in the engine for the factory to specify different rods sizes between carbs due to whether its automatic or manual behind the engine?

 Didn't receive an e-mail, but I called him.

 Basically what I/Mudsport have been saying, the M/T takes lesser amount of power, whereas the automatic transmission does. Converter slippage, clutch slippage, fluid transfer, rear differential, all have a roll in this. Jon told me 15%-25% power loss for the M/T and 35%-75% power loss for the A/T! Crazy! 

[DeCaff2007]

Wow, funny I was just going to ask this exact same question.  I have a 76 Trans Am with a 74 400/96 heads, th350.... but I have a factory correct QJ.  Pretty standard configuration, but I've found a good deal on a 79 ST-10 4 speed (which was mated to a 78 400).  I'm SERIOUSLY considering doing the 4 speed conversion. 

Now that I know it's just a matter of a different jetting kit, I may just go ahead and pull the trigger on this.

[Ethan1]

Wow, funny I was just going to ask this exact same question.  I have a 76 Trans Am with a 74 400/96 heads, th350.... but I have a factory correct QJ.  Pretty standard configuration, but I've found a good deal on a 79 ST-10 4 speed (which was mated to a 78 400).  I'm SERIOUSLY considering doing the 4 speed conversion. 

Now that I know it's just a matter of a different jetting kit, I may just go ahead and pull the trigger on this.

 It is more than just needing a jetting kit. You have to open up some passage ways, too. Restrictors, idle tubes, etc.

[MRSOFTE]

Thx for making that call Ethan.
Knowledge is power!!!!!  Especially here...ha!