Metering rod hanger depth question

[Bailey28]

I have built up two carbs, first one a 17059217, and the second a 17056202 both for my stock 350 Chevy. 

I found this paper advising to set the rods into the main jets by aligning the root diameter lip of the rod with the lower step of the main jet as pictured.

In both cases, I set the rod next to the jet and measure 1.950" from the top of the rod to the top of the jet.

I then install the jets into the bowl and install the rods and PP with the spring into the bore and adjust the APT to get the 1.950" which usually results in the APT around 1 turn up from bottomed out. 

However, when I install the airhorn gasket, I noticed that the gasket itself will not allow the PP and rods to go all the way back down to where  I set it.   I believe the hanger bottoms out on the paper gasket... I need 2-3 more turns out on the APT before the pin on the PP will come in contact with the screw. 

It is like the rods are too short once the gasket is in place to maintain the setting as described in the photo.  I have the 2.395" rods for both of these carbs.  40K and 48K respectively.   

Am I not setting the rod depth the right way?

[Cliff Ruggles]

"K" series metering rods only allow .005" adjustment for their entire length of travel and why I don't use them here.

So even bottomed out to out 6-7 turns you have very limited control of A/F at light part throttle or "normal" driving with either carb.

The power piston arms on the later APT models should be level and exactly even, and bottomed out with the APT down the gasket isn't a player anyhow especially with the later model Chevy large MAB units, they are typically WAY too lean anyhow and need the metering rods up pretty high to bring in enough fuel right to start with.......Cliff

[Bailey28]

Thanks.   I need to get the 50M rods and get them set up. It would seem that the depth with the 50M rods would be more critical to set right at the start of the taper for maximum effectiveness from .050 to .036.   

Forgive me if I seem a bit hung up on this, but I am used tuning motorcycle carburetors that use very detailed needles with regard to taper, L1 length, clip position, root diameter, etc.

Thus far however, it looks like the Quadrajet is a very tuneable carburetor which I am enjoying learning about.   

[Cliff Ruggles]

50M rods have .036" tips and do not work with late 70's large MAB Chevy units.  Those need our 44 full tapered rods instead.  They are .044" on the top of the upper section, taper gently to .042" then all the way down to the .026" tips.

As they are raised up with the APT they will provide FULL control of A/F and much greater range of adjustment than the "stepped" K series rods........Cliff

[Bailey28]

Great info!  I am making an order with the 44 rods and a rebuild kit for the 17056202 carburetor.

 What main jets would you suggest I order for this combo on a stock 350 with the large air bleeds?

[Frank400]

I've built a 17056202 and also quite a few of those large main air bleeds carbs, and I may suggest you insert Cliff's air bleeds in those .120 main air bleeds.  They'll end up at about .046"-.048" you can go from there with let's say a 72 jet and Cliff's metering rod, or drill them to .070" and follow Cliff's recipes in his book.  Everything will be soooo easy to tune after that.

    Frank.

[Bailey28]

OK, it sounds like I should just convert to smaller main air bleeds.  I'm thinking I need four of them, two in the boosters and two in the airhorn, correct?

After that can I use both Cliff's 44 rods or the 50M rods if I rejet to each specific rod?

[Frank400]

Yes you need four of them, like you said, and you need Cliff's 44 rod (with a .026" tip.  The M rods have a .036" tip and are for single main air bleed carbs.

     Frank.

[Bailey28]

Got the metering rod depth sorted out... The hanger was slightly bent off camber.  Both rods were even, but the whole assembly was bent on a slight angle.