TOPIC: Newly grooved, now what?

OK, so I added the carb spacer, 1" square aluminum type with mostly square and tapered insert in the middle from autozone. I also replaced driver side pcv with a breather filter cap, no hose to air cleaner. Hooked the hose from passenger pcv to air cleaner.
Then I grooved to full depth, a little past actually but not much.
Torqued intake manifold to spec, half were a bit under spec.
Installed carb, left pcv port on carb un capped, engine was very hard to start, barely ran for a couple seconds.
Then capped the pcv port on carb, it fired right up, idled fine slightly higher than before any mods. (Yes, opposite of last post!?)
When pressing accelerator it wants to die just past idle, but revs right up with some easy pumps of the pedal. Basically just trouble transitioning from idle.
Exhaust is still slightly blue (at night with my headlight), and more smelly than before all mods.
And now it sounds like I have a turbo on all the time the groove whistles as loud as the engine, maybe my over-cut.
It was late so I didn't get many pics, and still need to check timing and vacuum. More to follow soon.

Very good Geronimo! I bet the new spacer and new gaskets above/below the new spacer cured a vacuum leak. Your new PCV and Breather arrangement is just fine, I should have recommended it that way. Watch for any oil aspirating to air cleaner from PCV hose. We have fixes if that happens. Let's see what it's like after re-adjusting base idle, idle RPM, etc. Interesting you got a whistle, I've not seen/heard a carb do that yet, it's cool if ya dig it!

The cap on the carb PCV port- I use vinyl ones, all the rubber caps nowadays crack in a few months in my experience.

The blue smoke may be from oil that was being sucked in w/ the previous PCV arrangement, see if it persists or not. If the smoke is worse when under hard decell. in gear, then I'd suspect valve guide seals or the guides. Seals are pretty easy to swap out, a few hours. Again , is this a basically stock engine?

After you finish this round of tuning, drive it awhile and see how it does. If exhaust is only oil smoke, that's one thing, see if it has a rich fuel smell as well. The aluminum spacer adds plenum volume, that will help power. If you need help on jets/rods sizes or changes, I know the Edelb/AFB carbs pretty well, it can be confusing on the jet/rod size numbers. But actually it's simple. IF off idle stumble persists after this tune, you may want to increase accel. pump shot volume. Dist. advance mechanism could be sticky or worn, and check that the dist. vac. advance holds vacuum OK.

We can talk of other stuff later, tires. tire sizes, pressures, and some other tricks, depending on driving style locale and conditions. You are doing Great, Geronimo!

Tracy G

OK,  I adjusted the idle air mixture and speed, got the vacuum gauge up to 22.  That was with idle at 850.  Then I set timing to 4dg btdc as recommended by Haynes manual.  This seemed to bring idle down to 650, left that there.  No more blue smoke or oil smell from exhaust,  even on decel, but smells too rich.  Still have off idle stumble.  No mileage gains yet. Also it started to diesel (keep running for 1 sec) after key off.

I do not know if it has stock cams,  and the dual pcv was there when I bought it,  so don't know about tuning for it.

I put new spark plugs in, gapped them to .055, manual says .045. Old plugs were between .025 and .055, no black or white soot.

I drove it for a few hours, it ran OK.
Plugs are now black and sooty. Used a colortune glass spark plug to find out it was orange (rich) at idle. I adjusted the idle mix till it was blue (correct afr).
Also, I tried the paper on the exhaust pipe test, it sucks it in slightly.
So I added a quart of atf to the oil as Ron suggests.

Drive it 75 miles, still poor mileage and short diesel ing after key off. Maybe carbon still burning?

Carb tuning kit should get here today.

Add 2-4 deg. initiaL timing, see if you can back off the idle speed screw some to get 850 idle speed. If the exhaust smells Ok at idle, but stinky on the road, then yes it's too rich for primary metering.

What is idle quality like now- smooth, good throttle response, or other?

I'm assuming you are getting an Edelbrock tuning kit. I could go into a whole drone about decoding the size numbering system for Edelbrock and Carter, but if you tell me if it's an Edelbrock rod/jet kit, and If you want input, I'll help out.

IF you go to Edelbrock's website and look around, they have info about what jets and rods come stock with which carb's. You probably know that the carb # is stamped at left front corner (passenger) of the base. This tells which model # you have. Often the carb's have been left alone internally, but not always. Once you have which model# it is, you can look in the website at the tuning charts, or maybe the booklet comes w/ the tuning kit. The tuning charts give options for rod jet combos, but its just simple math. The rods have 2 size diameters in 1000'ths of an inch, like say .076 X .055. that would be stamped 7655.

Edelbrock just stamps the 2 number sizes into the rod, so Edelbrock would say 7655 in the above example. Carter uses a coded numbering system for rods, you need their chart for that. Edelbrock and Carter rods/jets physically swap same/same. The larger number is the thicker section of rod that will be down in the jet at idle and cruise. When you accelerate, or floor it, vacuum drops, the metering rod piston springs push the rod pistons up, and the thinner end of the rod(s) is now in the jet(s.) The metering rod pistons are controlled by manifold vac. sucking them down, the piston springs inside the rods push up against the vacuum, the 2 forces constantly balance against each other. This system is the Power Valve for an Edelbrock/Carter AFB, no diaphragm ala' Holley to blow out!!

SO- for everything except acceleration and full power, just take the primary jet size #, and subtract the larger rod size # from the jet size #, and you have the actual opening size of the combo. So, if you had a 98 jet and 76 rod (larger diameter part) the final size is .022. Same rod/jet combo, the power size # is .043. see? Once you know this, you can plot out the whole fuel delivery curve for the carb. Again, float height is critical, you want both floats the same. Once an optimal rod/jet combo is found, then tiny changes from stock float height can fine tune it.

If you are going to open the carb up to check the jets, I'd check the float height too. Somebody might have been playing w/ this carb, never know. Spray it out w/ carb. cleaner, you can't tell how clean it is from the outside. Good idea to hit all the tiny openings in the venturi clusters, you can pull 'em out 1 at a time. Often my experience has been, when an engine runs weird, get the carb back to factory baseline, get it clean, and go from there. Most of the time, if an engine is basically stock, these carb's do very well "out of the box". I can usually just change metering rods by one or two size steps, and leave jetting stock. That's a careful ten minute job, just loosen the metering piston cover screws, rotate the plate till the piston pops up, carefully lift the piston/rod out, and swap the rod, (hold on to the little rod retainer curly-spring, they like to fly off! ) I ensure the piston spring stays in the piston bore, I handle the pistons/rods carefully, and it usually takes a few gentle tries to get the piston to go back down in the bore don't force it, the rod's narrow thin end needs to line up into the primary jet.

With the way a previous owner/tuner did the dual PCV valve thing, I would be on the lookout for possible "tuning" inside this Edelbrock. The spark plug gaps are another indication. Once you have the Edelbrock tuning chart and info on what rods/jets it came with stock, you can compare to what it has now, and judge accordingly. IF you are in "left field" for tuning info for the rods/jets, then post the carb. model#, and the primary and secondary jet #'s, and the rod#'s of what it has now. I will look up the data in my books, and give info to help out.

IF you already know all this stuff, then more power to ya and maybe this will help someone else out.

Tracy G

OK,  set timing to 8dg with idle at 850.  Idle is pretty smooth, very  small fluctuations.  Exhaust smells normal at idle,  no fresh air coming out of there though. 
I put the color tune spark plug in,  still get blue on idle,  but at 2k rpm color flashes between blue and orange.
I just confirmed with the previous owner who installed this engine and carb.   He says it has stock cams,  and the carb is all stock.

Took it for a test drive,  throttle response is good,  except for a very slight hesitation off idle.  Smells like fuel in cab while driving.

I have never tuned or taken a carb apart,  but I am not afraid to try

I have an edelbrock tuning kit 1487 for a 1406 carb.

OMFG-- I just spent over 3 hours responding for Geronimo, w/ 8 pics, and tons of info, I tried to upload, and the site told me I was SPAMMING it!!

kill! kill! kill! ARGGHH!!

(Tracy resists the urge to hurl his vintage Carter AVS carb at the computer monitor in furstration!!!

well then...JFC I will try again later, good thiung I don't have an RPG lying around right now!!!


groan....

Tracy G

I feel your pain Tracey. I learned early on to copy my post to notepad before hitting submit; had a lesser but similar problem.
I pulled the metering rods that were in there, they were 7052 with 5hg springs. To avoid getting to the jets, I tried to lean the mixture with the rods I have in the kit. I used the 7347 rods with 3hg springs. Throttle response and power became great in cruise and medium accel. Full throttle got worse, so I figure the smaller opening helped a lot in the first part of throttle, and the larger opening let too much fuel in past that.
I'm waiting for a gasket kit so I can get to jets, then I'll see how lean I can go!
Do you think I can use original air horn gasket again if I take it apart, until I get new ones?
Also, I noticed that the vacuum advance on the msd distributor is not hooked up. Should I hook it up?
Btw, thank you very much for all your help

Geronimo- yes first test the vac. advance diaphragm, just stick a vac hose on see if it holds vacuum. Suck it down then wait 30 seconds to be sure. Can also remove dist. cap and check the centrifugal advance, watch for sticking of the weights, looseness in the weight pivots etc. Light oil on the weight pivots, if it acts sticky it might need torn down cleaned and lubed.

Well someone swapped out the metering rods from stock. You did the right thing w/ what you have on hand, I would have swapped the rods and springs just as you did.

IT might be that the jetting has been fiddled with. To avoid endless frustration/confusion with the whole rod/jet combo thing, since you have grasped it so well so far...

Just take the Primary jet size # in thousandths, like 98, then subtract the rod Cruise diameter size like 70, result is 28. Just simple math. Same thing for the rod Power step 98 minus 52 is 46. Understanding this, then multiply the result by 2 to get total fuel delivery for the primary side for both cruise and power. Result for Primary total delivery is 56 cruise, 92 power. To get total WOT delivery for all 4 barrels, just add the secondary jet size X2 to the final # for Primary power delivery. Understanding this, you can use the charts Edelbrock recommends, AND you can mix and match rods and jets in many ways. OF course, some of the combo's that seem ideal for Primary cruise may throw off the Power setting. IF you can find them, Carter made rods with different sizes than Edelbrock did, they all physically swap no problemo.

I'll go ahead and try again to upload the pics I took of my old rebuilt Carter AVS. I got views of the exterior linkages and the little hairpin clips that hold 'em. I will come back and try to attach a youtube video from a pro carb rebuilder showing taking apart a Carter AFB. The Carter and Edelbrock are virtually the same carb, the differences are subtle. This guy is a pro, so he attacks the AFB like a hungry animal IMHO! I'm more deliberate and slow. As you watch the video, you will see he doesn't remove the 3 exterior linkage rods in deliberate fashion like I do, he just yanks parts and chucks 'em off the camera view But he's prob done it so many times, plus he has spare parts too. He does point out the accel pump S link, it should look like letter S from front installed right. Just look at yours closely before dissasembling it. You CAN open it up on the engine, but I advise pulling it off, dumping out the gas, then take it to a good place w/ a clean floor so you can find any clips or anything that gets away from you. You only need remove the top to get to the jets, and usually the top gasket will be OK. IF it acts like it's gonna stick and tear as you gently pull the top up, shoot some carb cleaner or even WD 40 at it and let sit a moment then proceed. Would be good to have a kit on hand first in case.

You can check the dist. out first while waiting on the rebuild kit, getting it right should also help. When you know the vacuum advance/dist. is OK, connect it to the left hand front vacuum port on carb bottom front, it's higher than the right one. The Left port is called Ported vacuum, it sees vacuum after the throttle plate rotates open past it. The right hand port is Manifold vacuum it has full manifold vac. all the time. You can see which one it likes better. OK I'll post this then add pics, then the youtube link.

I get the impression that the previous owner or someone was trying to Hotrod this thing, Iv'e seen stuff like the PCV setup, wrong base plate/gaskets, dist. and carb messed with before, it takes careful deliberate work to tune dist./carb setups, one thing at a time!

Tracy G

Geronimo, looking at the chart Edelbrock provided in the tuning kit, I'd see about ordering the stock size 7547 rods. Jets- it's hard to say without knowing what's in there. With a stock engine often the stock rods/jets work quite well. In the end, I bet you will be surprised just how well this Suburban can do with the Groove and correct tuning!

You are doing very well my friend! BTW, if you have a good digital DVOM electrical multi-meter, you can take any plug wire and check the Ohms resistance, there may be gains to find there depending on what's there now... ( Ignition Freak speaking....) This works best if there are alligator clips on the leads to get a good attachment to the wire terminals.

Tracy G

OK, I haven't checked distributor yet, but did take the carb apart to swap primary jets. It had .098, swapped to .095. It looked clean inside.
Here is what my final groove looks like.









I need to smooth the right groove to eliminate whistle at idle.
I wonder if the groove position being against the fully closed throttle plate is causing the terrible stumble off idle that I haven't been able to get rid of yet? I increased the pump shot on carb to the closest of the 3 holes, that helped a little, but maybe it's getting too much air off idle?

I know I went too deep on right groove. . Oops, maybe I should've tried on a cheap carb first. .
The engine was a little hard to start before the groove, required some pumping of the pedal and a couple cranks, but warmed up quickly. Also before groove it would get up and jump over the starting line, now it can barely fall over the line unless I carefully tap the pedal, then starts to take off.
Boy this is quite a learning curve! I hope it saves me some $ on fuel
Maybe making the groove work on my 2006 Buick terazza with its efi and ecus will be easier. .

Unfortunately Geronimo, the R.H. Groove broke thru pretty badly, and in the critical center part too. I doubt that side is giving the desired waveform, though it's likely doing some good. Possible to fix? I'd be uncomfortable trying to epoxy in that area to re-Groove, there's nothing to support any epoxy there. IT MIGHT, I say, Might, be ok to fill it in carefully, sand it flat at bottom, and re-Groove, I think I would want a 4-hole carb spacer that had a bore size exactly the same as the bore of this barrel. with a matching thin base 4 hole gasket in between, a spacer to match this carb bore MIGHT give enough support. Would make me nervous though!

Live and learn. This is why I say practice first. The carb looks pretty good otherwise, the accel. pump piston cup looks off color, I'd verify it gives a good pump shot w/ air cleaner removed. It might be optical illusion, but the floats look to be at different heights, did ya check? There is some light color crud sticking to the floats as well, fairly common, I would spray that carb out and blow out w/ compressed air if it was on my bench. These Edelb/AFB accel pump cups do go bad over time, they can dry out a bit of get a wrinkle if left dry in hot climate. I do see 'em at parts stores ala' carte as separate parts for sale. You have a kit coming anyway, right?

One thought- IF this carb won't tune right due to the bad Groove, might start watching Ebay/Craigslist, they are still fairly common carbs. IF you replace it, try the Medium bit first!

You're gaining a bunch of knowledge here, Geronimo, some of it comes easier than other parts!

Tracy G