Float level and other Qs

[Macadoo]

Hi folks, new member here

I just bought Cliff's book.  I thought I knew a lot about these carbs, but wow!
So, a couple questions, if I may.  I just broke-in my first ever engine build.  An Olds 455, 030 over, Wiseco HC pistons (9.8:1 CR, if my numbers are correct), Howards cam (.512 lift in and out, 227/233 duration, 110 LSA), Edelbrock performer intake, Hedman long tube headers, holley fuel pump with regulator (althoug it doesn't seem like the gauge is consistent), 200-4r OD trans with lockup, 3.73 rear gears.

I'm, of course, having major idle problems with the Qjet calibrated for my old small block.  I'm through most of the book and it all makes perfect sense.  I have a couple of carbs to play with.  The one on the car now is the original '71, #1705... but I've started a rebuild on a 1981, 800 CFM from a checker cab.  #17081287

Q #1. The book says to go with a float level of 1/4" if the stock setting is unknown.  I've looked up the stock setting but I doubt the checker cab had a high performance 455 (461) under the hood, lol.  The paper says to set it at 15/32 for an '81 455.  What's the best compromise here?

Q #2.  Although the pictures in Cliff's book are excellent, I still can't seem to figure out where the upper air bleeds are on this '81 carb.  I think they're in the air horn, recessed in a shallow channel, but these holes don't go all the way through.  If I understand the book correctly, there's a good chance I don't have to mess with them but I'd at least like to measure them.

Q #3.  I've never had this wild of a cam but from what I've read, a properly tuned Qjet shouldn't idle erratically.  I really have to crack the primary blades to get it to idle.  The carb that's on it now (the '71) has the idle bypass circuit in place and hoes drilled into the primary blades.  Yesterday, just to get me by, I pulled it and enlarged the idle screw holes to .1065 but that didn't have any effect.  I guess what I'm asking here is, by following recipe #2 from the book (with the '81 carb), will I get it to idle well enough to run AC without having to add a solenoid to bump up the idle?

Anyway, nice forum you have here.  Very informative.
-Mac

[Cliff Ruggles]

A 455 with that cam on a 110LSA will have a somewhat "ratty" idle and require idle system modifications.

Opening up the holes under the mixture screw do nothing without increasing idle fuel to them.

Can't help much not knowing all the parameters of that unit, but I would identify what you have, measure all the players, and make improvements to the areas that need help.

Being a 1981 emission calibrated unit it's going to need larger idle tubes, DCR's, and possibly a little smaller idle airbleeds.

It will also need larger main jets, and I'd recommend using our custom primary metering rods and smaller secondary metering rods.

We sell rebuild kits with tuning parts for any carburetor part number as a "package".  This will include the necessary high flow N/S assembly to keep up with your 455, HP accl pump, small float, secondary cam/spring, new PP retainer, gaskets, small parts, filter/spring, jets, metering rods, PP spring and secondary metering rods.

We can also include idle tubes (pre-drilled if requested) with the kit. 

This will take the guesswork out of setting the carb up so basically "plug and play"......Cliff

[Macadoo]

Thanks Cliff.  I appreciate the input.
Do you recommend a 1/4" float level?  And "custom" primary rods?  Are these different than the B (pre 75), and K, M, and P (post 75) rods?  I've been through the book but I haven't been around this website yet.
Happy 4th!
-Mac

[Cliff Ruggles]

We offer full taper 50C rods for the single main airbleed later units.  They taper from .050" all the way to .036".

We also have custom .044" rods that taper from .044" to .026".  Those have a gently taper on the first part of the upper section, then quicker down to the .026" tips.

Since you have a fuel pressure regulator I'd set the float at 9/32" and pressure at 7 to 7.5 psi with our high flow .135" N/S assembly.  That should keep up with that engine, if not get the .145" seat......Cliff

[Macadoo]

Hey fellas, it's been a little while since I posted.  But I went through Cliff's book and used recipe #2 on an '81 Q-jet with APT.  I installed it, grabbed my neighbor, and ran down the road.  When I punched it, it scared us both, it was so fast.  However, it still wouldn't idle worth a squat and had a hard time starting.  I found that the mating surface on the Edelbrock intake was all jacked up and uneven and sucking air.  I got it flat now but that Quadrajet is now warped, I'm sure from bolting it to the uneven surface (or maybe it was to begin with).
I have another that looks very close to my original '71 Olds carb but the fuel bowl was replaced and has no numbers.  D'oh!
Cliff, can I post pics of the carb and gaskets here?  Maybe you could post the part numbers of the gaskets I need?  I don't need the entire rebuild kit since this was a carb I bought a couple years ago from a rebuilder.  Now that I know MUCH more about these Q-jets, I can tell this was a decent build for my old small block.  I just need to match it to my BB, now.  I'll need the gaskets and some odds and ends.

[Macadoo]

Thought I'd go ahead and add some pics.

[Macadoo]

Air horn gasket

[Macadoo]

Base plate

[Macadoo]

Main body, top

[Macadoo]

Main body, bottom

[Macadoo]

Air horn, bottom, has six tubes.

[Cliff Ruggles]

Our basic kit will have all the gaskets, plus the high flow N/S assembly and HP pump at no additional charge.  A much better bargain than buying the gaskets separately and you'll need the better N/S assembly and pump for the big 455 anyhow......Cliff

[Macadoo]

Sounds good, Cliff.  But I still don't have a carb number to plug in.

[Cliff Ruggles]

Doesn't matter I can see enough in the pictures to provide the correct gaskets, the N/S and pump are universal......

[Macadoo]

Thanks Cliff, that helps.

I've been reading the Q-jet tuning article by Lars Grimsrud, particularly the table that contains the factory jetting for different motor combos.  It seems that the higher compression motors from the late 60s were setup leaner (and meaner?) than the 70s EGR units.  The EGR motors ran very rich with jets as big as 77.  For example; a 1974 Vette with a 454 BB motor ran 75 jets with a 39 rod (manual trans).
My question is; how does a more aggressive cam change the jetting?  More lift with more duration would move more fuel, would it not?  I was thinking of installing 74 jets with 49B rods (this is the 1705 era carb) but now I'm thinking that would be too lean.  I don't wan to burn my new valves