88305tpiT/A

iTrader: (2)

Hello,

I am looking for jet and rod reccomendations for the new 383 I am building. It should be about 9.5 to 1 with flat tops and 76cc chamber world SR torquer heads. Manifold is a weiand Action Plus with a Non-CC Qjet on top. I currently have #74 main jets in it and I am not sure what letters the main rods or secondary rods are.

The camshaft will probably be a Comp extreme roller specs: 210/214 @.050, 260/264 @ .002 with .474 lift on both. LSA is 111.

I will have 1 5/8 longtubes with mufflers but no cats and I doubt the motor will ever see above 5000 RPM.

I can get the Carb serial number if it helps. I hope I provided enough information to give y'all an idea of what primary jets and secondary rods i should look into buying.

Thanks.

Damon

You need to know what primary and secondary rods and hangers are in it now.

Here's how I'd set it up, just making an educated internet guess:

Your 74 primary jets aren't far off. I'd go with 76s, personally, but you're not far off.

Primary rods: 44K or thereabouts. If the carb has an APT screw for the primary rod piston then screw it all the way down with these rods. If you're going to play with the APT screw then the primary rods can be a higher number- like 46-48K.

Secondary rods: DRs with a G hanger. Marginally lean for a strong 383, but a good get-you-in-the-ballpark choice, if you're going to step up to the larger 76 primary jets. If not, stick in a set of DA secondary rods on the same G hanger.

These recommendations will work for MOST typical QJets, not all.

88305tpiT/A

iTrader: (2)

Awesome -- thats the kind of info I was looking for.

I will have the carb off and apart tommorow or sunday and will look for the primary and secondary rods letters then and post back.

88305tpiT/A

iTrader: (2)

Ok I finally got the carb apart. it is a 17059229. It doesnt look like I have an APT screw unless I am completely blind or it is missing. The secondary hanger has what looks like an L stamped into the rear top surface opposite end from where the rods hang. It also has the number 33797 stamped on the curved leg of one side of the hanger. The secondary rods have DP stamped both vertically and horizontally on the shafts above the taper.

The primary rods are not so easy. I definately need to get a magnifying glass or microscope but I think they are 50V or 50 something, could be K but I have no idea. And as I said above I have both 72 and 74 jets.

On a side note I asked my machinist (who I thought I trusted) and he scoffed at my 74 jets. He thought that would be WAY rich and suggested I go with 69's or 70's. When I told him the plugs looked very white he said "you cant tell anything by plugs with today's gas. You will be way to rich if your plugs actually show color."

I am open to anything at this point in terms of advice. I want to get the motor running on this carb but I do have plans to TPI it in the future so I will have the opportunity to get and O2 sensor's read on things when I do that.

Thanks again for any help.

Sonix

iTrader: (1)

Yea, that sounds like a typical old truck Q-jet. DP's are like fingers, they're HUGE! (that's bad). Or maybe i'm just thinking of the DD's.

Find some reasonable secondary rods.

The primaries can be all over the place, some older vehicles took a 70 jet, with a 50 rod, and ran fine, others took a 73 and a 41, and ran fine. It really depends on the air bleeds.

Check for some of my old posts asking about this, but the main thing is to test it out. You'll probably want to drill out your mixture screw holes, so you can get some mixture adjustment. You may need holes in the throttle blades, but if you run enough timing you can probably get away without it. Just make sure your primary blades aren't further than .040" open, (in height, not gap of blades), otherwise you'll get an off idle stumble.

Then go ahead and lock out your secondaries, and tune your primary jets. Run WOT runs up to 50mph or so, and time it. Do 3 runs or so, make sure you can get it consistent. Then swap 2 jet sizes in a direction and try again. Plugs are really hard to read, guess based on power and speed. Your butt dyno can lie to you, but a good stopwatch won't.

Once you get that right, cruise on the highway and see what primary rods do you the best. Remember, your primary rods won't effect your power, only cruise. They all have the same power tip (some exceptions).

Then finally unlock the secondaries, and play with rods and hangers. I think DA's with an F or G hanger would work nice.

I don't think you'll have to modify your pump shot, at least not yet.

I'd forget the hope of running TPI on that 383.

88305tpiT/A

iTrader: (2)

Thanks for the great info!!!

Ok so the jets and power tips on the primary rods set the WOT primary mixture. The primary rods set cruise mixture and the secondaries come last.

I think I will put the 74s back in and stick with my 50 rods. But I will replace my secondary rods with some DA's and a G hanger.

88305tpiT/A

iTrader: (2)

So I just checked summit and it seems edelbrock only makes the following secondary rods
CK,CL,CE,CC,AY

Would any of these be ok? or is there another place to get a set of DA rods?

Thanks again.

88305tpiT/A

iTrader: (2)

Uh Oh...

I was putting the carb back together and I broke one of the air valve retaining screws off in the shaft. I knew it would be hard to get those little screws in and out since they were staked in but the other 3 went in just fine.

Anybody know where I can get an oversized screw? I probably should just ask -- is there an online source for drill tap and screw around? I did some searching for Q-jet parts and was wondering if this kindof thing might happen alot.

Any Suggestions appriciated. (including that I'm a dumbass for even taking them out!)

Sonix

iTrader: (1)

oh, you broke off one of the screws holding a plate onto one of the air valve shafts? Hmm, I guess you can try to drill it out... Maybe get a left hand drill bit and drill through it, and hope it pulls the screw back out.
Check mcmastercarr.com for that type of thing.

88305tpiT/A

iTrader: (2)

I think I will drill it out the right handed way since I got it almost all the way through before the damn head poped off.

Ill check mcmaster for the screw size.

88305tpiT/A

iTrader: (2)

Its ALIVE!!!!

It took me a couple trys to set the timing but eventually I got it to run right. Sounded good.

It got to 200 real quick but I kept an eye on it and shut it down. Only took about 10 minutes. In that time I set the timing, idle mixture screws and filled the coolant.

Next time Ill fill the trans to full and check the advance. I am going to have to wait till tommorow to start it again though -- long but funny story.

A month ago when I was assembling the internals I had this quart of oil with the top cut off for dipping stuff in oil. Well I kicked it and the oil went all over the headers which happened to be sitting near the stand. I didnt forget this today when I started it but wholy CRAP did it smoke. I remember cleaning them as much as I could but they were rusty and I guess they held alot of the oil I spilled. I had the extinguisher ready and in hand for a minute there cause I thought the oil might catch but it didnt.

Anyway tommorow is round 2 where I will start and run to temp a couple more times then drain the oil and put the front wheels back on so I can drive it.

88305tpiT/A

iTrader: (2)

So I got the LC1 wired up today and its going to be money well spent. I am around 15.5 to 1 when just cruising around but WOT is 13 - 13.5.

I will unscrew the APT stop some as its all the way down at the moment. After that I guess I will look for some even thinner secondary rods (CE's are what I have and I thought those would be pig rich!).

I noticed that it was idling at 12-13 to 1, Is that normal? I set the idle the normal way, with a vacuum gauge, but this seems rich to me.

Any suggestions for what A/F ratio I should shoot for at the different loads and how many turns out on the APT screw would put me at 14.7 from the 15.5 it is now?

Thanks!

Sonix

iTrader: (1)

Yea, you're going to idle significantly more rich than stoich, that just seems to be the way it goes.
You might find it's faster with it even richer at WOT, like 12.5:1 even.

Try turning in the idle mixture screws, if the vacuum doesn't change you're ok. Keep going until vacuum drops off or idle speed drops off. See what the mixture shows then.

How much was the LC1 setup that you bought? Did you just buy the O2 sensor, or the whole package with a gauge of some sort?

88305tpiT/A

iTrader: (2)

I bought it from Craig Moates. He sells the LC1 kit (sensor and controler) with a little LED programable display that Craig makes (O-Meter) all for 200 bucks. http://www.moates.net/product_info.p...roducts_id=134

Its a smokin deal and should cover anything I want to do including providing a 1V signal to any GM computer to simulate a narrowband signal.

Thanks for the help!

Sonix

iTrader: (1)

Interesting... I've never dealt with wideband stuff, so a few questions if I may;

I'm wondering what is in "The LC-1 is a complete wideband controller built in to a sealed cable"

I currently use a narrow band O2 sensor in a bung in the Y-pipe, hooked up to power, and measure it with a voltmeter. Then do the math in my head later.

Couldn't I just buy his 5 wire wideband sensor for $80 and do the same thing? I'm not sure what those 5 wires hook up to, or why i'd need the "LC1" thingy

88305tpiT/A

iTrader: (2)

well Im certainly not the expert but Ill tell you what I know...

the LC1 controller basically operates the sensor heater and pump which I gather need more than just a constant voltage like most heated narrow band sensors. The controller performs calibrations and things that I dont understand but that seem to make the sensor itself pretty useless unless you have one.

The LC1 also has a bunch of nice features for outputs. It has a 0-5V and a 0-1V analog output, both of which can be programed with almost any curve of Voltage vs. A/F ratio. You program the curves with a laptop which can be plugged into the LC1 via a serial connection. You can also use the Serial connection to log the output digitally in real time.

If you are creative and determined I am sure you could come up with your own wideband sensor controller but I am certainly not.

Damon

You'll be wanting those 76 primary jets now (or even a set of 78s). Going richer than the DA rods won't help you much- there's not mech "flow area" left on the tip to give up at this point. It's gotta come mainly front the front of the carb now.

Look for the APT screw in a well directly in front of the primary power piston. It's got a funny looking head on the top of it that you could grab with a pair of needle-nose pliers, if your carb is so equipped. That would be how you lean out the part throttle mixture again once you step up the primary jetting.

ALTERNATIVE SOLUTION: Again, you need to KNOW what primary rods you've got now before you consider this. If they're typical 50-52 sized rods, chances are they are "M" style rods with a fairly large .036" power tip- measure them with a micrometer. That's what they used in the 80s on a lot of non-computer controlled QJets (truck carbs, etc.). You could go to an older "K" style primary rod which uses a smaller .026" tip diameter and effectively fatten up only the full throttle mixture (assuming you get a similar part throttle diameter on the fat part of the taper- i.e. 49K rods, for instance). Going from a .036" primary rod tip to a .026" primary rod tip is equivalent to jetting up about 4 primary jet sizes at full throttle.

Leaning the idle mixture should be as simple as turning the idle mixture screws in a little. This will always be required if you've fattened up the entire idle circuit system such as Sonix described. Don't think you're going to get down to a stock-type 14.7:1 at idle, though, in all cases. With bigger-than-stock cams it's always going to want to be a bit fat to idle best.

And DON'T go by exhaust smell! It's absolutely meaningless on a motor with no emissions and a performance cam. It'll always stink like fuel to a greater or lesser extent- that's a function of cam overlap and how much unburnt fuel it dumps into the exhaust at idle- nothing you can do anything about. I've tuned them for a long time now and there's only one way to do it right on a performance motor- set the screws where they need to be for best idle. Period. If it's a bit fat, so be it.

88305tpiT/A

iTrader: (2)

76 jets are in it. APT screw was all the way down though so I will unscrew it a bit to get the mixture better.

As I said above CE rods are what I used and supposedly they are a good bit richer than DA's.

Thanks for the suggestions Damon.

Sonix

iTrader: (1)

Hmm, interesting, I may have to look more into this.

I don't have any interest in datalogging, I don't even have a laptop. I just really wanted to see my AFR while I was cruising, WOT and about 1/2 throttle. See it, tweak it, then put the parts in the garage for a few years...

88305tpiT/A

iTrader: (2)

Running much better now. I backed the APT screw out like 4 turns and each of the idle screws in 1/4 of a turn.

Idle is now right around 13 to 1 and cruising is right on at 14.7 to 1 only very rarely going above 15 or below 14.5.

Thanks again for all the help!

James.