Float level and other Qs

[Cliff Ruggles]

The "M" series rods are shorter and used in the later Q-jets with the APT system in front of the power piston.  For the most part they were used in the single main airbleed models with few exceptions......Cliff

[Macadoo]

Okay, I have the '81 Checker Q-jet (M4MC) installed and it runs great!  Very crisp throttle and hard launches.  The idle is MUCH better now that the mating surfaces are all sealed up.  It is, however, dropping too much when put in gear; from 1100 in park to 700 in Drive.  The torque converter is a 2500 but the brand doesn't get great reviews (it came with my 200-4r).
For the carb, I used 74 jets with 56P rods which actually measured at 048 at the widest so maybe they were machined?  Half way down the taper they measured 44 so I raised the APT in an attempt to get that .030 range.  The only thing is; it pings at WOT, where as the Holley did not.  So I must be running a little lean.  Initial advance is right at 14* (recommended for my 455 setup) but I haven't checked "all-in" with the HEI.  Truth be told, I haven't had the guts to stand next to this engine I built myself with it running at 4k RPM 
I'm wondering if your modified primary rods would be a better/richer fit.

[Cliff Ruggles]

P metering rods should taper apprx .010" on the upper section unless they are worn down some.

I do NOT put used metering rods into our builds here, most are worn down and often flat-sided, and the jets are typically "egged" out some as well.

Pinging at WOT could be sucking the bowl low and going lean, may not be a tuning issue.

Our "M" series metering rods are full taper with .036" tips and designed to be used in the later model single MAB models.......Cliff

[Macadoo]

The 74 jets I bought new last summer and never installed.  The rods are questionable, as they came with the "rebuilt" carb.
I'll replace the rods and play with the fuel pressure.
Thanks for your patience, Cliff.  I'm happy with my progress.

[Macadoo]

Okay, well, this is embarrassing but I was told at a car show that I was cranking down on the distributor bolt too hard.  I went out this morning to figure out the pinging and the bolt was loose and the dizzy had jumped forward.
I started from scratch, set the initial at 14* with vac disconnected, played with the fuel mixture screws for best vacuum, and locked it all down.
I went out for a test, shifted from 1st to 2nd (200-4r) and hammered it.  The darn thing broke loose at the 2-3 shift!  I laid a short patch in 3rd gear so I must be getting close.
Cliff, would the shipping really be just $5 for a couple rods?  I'm looking at the 44s and maybe the secondary rods.

[Cliff Ruggles]

Shipping to where?

[Macadoo]

61753

[Cliff Ruggles]

Flat rate shipping this month for any shipments in the USA no matter what parts are purchased.

I would recommend installing new jets with the metering rods, unless you bought them from us.  Currently there are 4 different jets on the market being sold for Quadrajet carburetors and 3 styles do not work.

We sell the correct jets made to OEM specifications so the depth of the orifice in them is where it's supposed to be.

We can also so USPS First Class shipping on very small items for even less if you call the shop directly to order, usually around $3-5 dollars if the total weight is under 1 lbs and they will fit in an envelope of small package.......Cliff

[Macadoo]

I called and ordered the parts today (main rods, jets, and secondary rods).  The dude I talked to was really cool and we chatted for a while.  He thinks, and I tend to agree, that the 110 LSA is at least part of my idle problem.  But I'm stuck with it for now so I'll make due.
The other day I accidentally knocked off a vac hose (direct to manifold) and the idle sped up and smoothed a bit.  When I did the mods I drilled the idle bypass in the baseplate (and plugs in the main casting) to .106.  The fellow I talked to said I need at least .110 for my motor.  But .004 doesn't seems like much.  Should I go more than .110?

Carb #17081287

[Macadoo]

Okay fellas, I'm having trouble nailing down my tune for this 461.  Seems like I get it close and then I lose it.  I think a lot of it is the 110 LSA on the cam.  I can get it to cruise very smooth and to break loose at the 2-3 shift but it pings at WOT.  So I dial it back just a little and it becomes a turd.  It likes a quick timing curve but the mark bounces around at idle (800 rpm in park).  So I put in stiffer springs (two medium) and it becomes a turd at part throttle. (HEI)
Today I tried limiting the mechanical advance to about 12* and bumping up the initial to 21* and it runs "okay" but I know there is more power there.  I realize that's only 33* total so I need to trim my mechanical limiter a little.  And it's a little hard to start when hot with 21* initial.  No kickback, just a little slow turning over (Summit mini starter).
I'm still dialing in the Q-jet's APT but I've got it close.  No stumble and good cruise mileage (18 mpg - ish with my 200-4r and 3.73s).  That's using Cliff's tip-in method at 2200 rpm.  But I can still pull the AC vacuum hose and increase the idle (manifold vacuum).
Idle tubes are at .038
Down channels .055
Idle bypass air is at .120
Jets: Cliff's 73
Metering Rods: Cliff's 44
Mixture screws are 3 turns out giving me a steady 14 inches of merc
I do have a 1" spacer under the carb for clearance reasons.  That may be part of my low part throttle power issue.  I could probably get away with a 3/4" but not much less.
Engine runs strong and pulls HARD but only if I push the timing past the safe zone.
Thoughts?

[Cliff Ruggles]

Is the spacer 4 hole, fully divided, or open?

[Macadoo]

Hey Cliff,
It's a four hole phenolic.  It wasn't real flat when I bought it but it sanded flat pretty easy.  But I don't think I can take a 1/4" off by hand.  Although I do have a wide belt sander at school. 

[Macadoo]

Oh, and the carb/spacer are sitting on an Edelbrock performer dual plane manifold.

[Macadoo]

A small update:  my dial-back timing light is a POS.  I put my old light on it and, although I can't see the timing mark since it's so advanced, the nicks and other marks on the balancer are rock-solid steady.  I'm making a timing tape and will get it on tomorrow.  I was real close to pulling the distributor to have a look at the gear.

[Cliff Ruggles]

I've done a lot of testing with spacers and have found them for the most part to be a waste of time/funds.

They create issues by raising the carb up higher, like hood clearance, choke tubes, throttle cables, etc. 

On my 455 making over 550hp I did some drag strip runs back to back with 4 different spacers.  4 hole, fully open, fully divided and semi-open (divided in the front and open between the secondaries.

I also drove the car on the street with all 4 of them to get a "feel" for how well they worked there as well.

The 4 hole and full open were horrible at the track, slowed the car down everyplace and the fully open induced a huge stumble going to full throttle.

The fully divided did OK, and I ran the highest MPH with the semi-open.

However, when the smoke cleared and dust settled, the quickest ET was with no spacer at all, just a 1/4" thick factory gasket.

I also did some intake testing.  The Edelbrock Performer was a "turd" on my engine, and couldn't even make a full throttle pass as the runners are smaller in cross section than a stock one.  The engine hated it.  The RPM did fine, and I also tested a Holley Street Dominator, Torker and Tomahawk.

All the single plane intakes ran slower everyplace than the dual plane, and required a 1" open spacer to work well.  The Tomahawk ended up running the highest MPH but slowed the car down considerably in 60' times.  Once again the factory iron intake ran the quickest ET, so it was making the most average power.

Folks in the Pontiac World cried "foul" because I had modified the iron intake by opening it up under the carb to the same apprx size/shape as the RPM intake. 

For SBC builds it is hard to beat a stock iron intake to at least 450hp.  They are excellent, low profile, very well made, etc.  Even so we see them tossed out all the time for aftermarket intakes and folks think they are making more power.

A few years ago I did some back to back dyno testing with a 428 Pontiac engine.  It had aluminum heads on it flowing 260cfm, 10.7 to 1 compression, and custom ground 236/242 hydraulic roller cam in it.  I tested a factory aluminum HO intake, Edelbrock RPM, and my "modified" iron intake. 

The HO made 487hp, the RPM 491 and the iron intake 497hp.  Keep that in mind when you buy a Performer, Performer RPM or even the larger Air Gap version for you little SBC engine build make considerably LESS than 500hp.

Looks like you may have found your tuning issue.  No real need for timing tape, I just measure over with a tape measure and put a mark at 36 degrees with a paint marker.  You can reference off of that mark when setting the timing, etc..........Cliff