Started from scratch with the Edelbrock, advice needed...

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SnoMan wrote:


SnoMan,
The Edelbrock 1406 is in fact an enhanced version of what we used to call a Carter AFB (back in the dark ages), almost identical, and I bet some of the old gaskets would still interchange. The Quadrajet was a very different animal. The only similarities I can see is the vacuum operated metering rods, all else is very different.
Right out of high school I ended up in a Delco factory training school (they used to train their techs, back then) and was one of the first in the state (Oklahoma) to be certified to work on that beast (Quadrajet) and what a beast it was in the first iteration. It improved magnificently over the years.
All this carb talk does take us back some, doesn't it??
George
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Well... I have a set of the .095" jets... I'm going to put them in tomorrow and play with my existing meterings rods (I have 3 sets). If I get time I will pick up another set for experimentation.
I laid all the metering rod and jet combos out in a spreadsheet, and after running a few formulas to determine the flow area (area of the jet's hole minus the area of the metering rod) I was able to sort them in a logical order.
Needless to say, after that, I have little respect for Edelbrock's calibration chart.
Honestly though... I think the one thing that would help more than anything would be an O2 sensor and a fuel/air meter. At least then I could actually see what was happening, and when and where in the RPM and vacuum ranges.
You're not confusing me... I've learned a lot about carbs in the last year or so, and I keep my nose in the manual and constantly read websites to try and get a little more insight into what's going on.
Basically, I still think it all comes back to a carb that's not calibrated for that engine, with that cam, with that kind of (low) vacuum. I just need to find that balance.
~jp
SnoMan wrote:

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wrote:

You are 100% correct here. BTW with your current came you want it to start in enrichen around 8 or 9 inches or so and that fact that the opwer vale is felt it tell me that you might be a little lean in mid range and as you richen up jet or metering rods you sometimes need to size down power valve.You migh also try have power valve come in at maybe 4.5 too. I agree that a A/F sensor would help a lot here. I had it down to such a science that I used to run once size in summer months and two size larger in winter months to keep it at peak performance. Trust me it is worth the effort to get it right and ift is very important to watch your plugs too and be prepared to change the heat range of them if you want best possible performance. ----------------- The SnoMan www.thesnoman.com
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The A/F meter will be the next serious purchase.
Then I gotta get a bung put in the exhaust manifold...that'll be fun--not.
I may end up trying to find a set of '87-up manifolds and go ahead and swap them out. That way I'll be set up for the O2 sensor from the get-go, and it'll probably make the future TBI swap that much less involved.
Either way, I need it running good enough so I can start reconnecting the emission control equip to get it titled in GA. I'm still running TN tags (don't have emissions in TN) and as much as I hate to consider myself anything but a Tennessean, I've been here longer than the law would prefer without becoming a "proper" citizen.
~jp
SnoMan wrote:

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wrote:

The best factory exhaust manifold ever made for a SB were made in the 60's and early 70's and they were wheat we called the old "Ram Horn" style and they flowed well. They came in two sizes 2 ich and 2.5 inch dump but I am not sure if they would fit/work in your application. Granted, they would not have a O2 sensor port but you could add one to the pipe right beow manifold. . On the air fuel sensor probe. You could drill a hole in exhasut manifold and then tap it to take a bolt or plug so that you can seal it when done. ----------------- The SnoMan www.thesnoman.com
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Does it need to be in the manifold for best results, or can it be downwind a ways?
Just trying to make this easier.
~jp
SnoMan wrote:

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Also, is the standard GM O2 sensor a narrow band or wide band?
~jp
SnoMan wrote:

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Jon R. Pickens wrote: Jon R. Pickens wrote:

Jon,
I guess a simple question is in order here. Do you have the owners manual that comes with the 1406 carb?? It contains a very good setup procedure for your carb. I can't see how it wouldn't contain pertinant information to get you out of your situation.
If you don't have it, you can go to www.edelbrock.com and download it, it is a .pdf file.
George
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Oh yes... I know it well, LOL...
I'd like to print up a few hundred copies of the PDF manual--to use as fire-starting material.
Actually, the main thing that's not being addressed here is the cruise mode. The springs are advertised as bringing out Power Mode at a certain vacuum pressure, but nothing is mentioned about when the cruise mode comes into play.
Is it 10" Hg??? 8"? 6"?? The carb obviously does not go from idle circuit to full-on power mode.
I need to figure that part out. Then I can play with rods, jets, and springs according to find the balance I'm searching for.
The funniest part of the whole thing is...I've literally cost myself in the thousands of dollars with everything I've been through (some self-inflicted) with the truck. But in a sick way I like it, LOL... I'm forcing myself to learn so much about all aspects of it and I love it!
FYI, the exact link for the manual is here: http://www.edelbrock.com/automotive/eps_intro.html
Had it bookmarked on both the home PC's as well as the work PC for some time now ;-)
Also emailed Edelbrock, and I'm still waiting to hear back.
Thanks...
~jp
George wrote:

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Jon, I used to run these carbs as afb's ( 2) on my 426 S/S Belvedre Ramcharger and played with jetting and metering rods for 25 years of competition and did not find theem sensitive to these changes, keeping in mind I was running flat out, but even driving part throttle around the pits I did not see a problem. I don't think your entire issue lies with the carb, it is somewhat large for you gearing and application as mentioned a 650 would be more inline. BTW GM sensors are narrow band for the most part.

-
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Too large or too small of a carb?
Mine's a 600cfm and you think more would be better???
I'm geared at 3.73 with 31" tires...
~jp
Shep wrote:

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wrote:

600CFM is about right but 3.73 are not the best with that cam and it would run a lot better with a 4.10 as it would get it on the cam quicker and make better use of improved RPM range. ----------------- The SnoMan www.thesnoman.com
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Yeah, but...I just had the rear axle rebuilt 7 or 8 months ago. I don't want to do that again. I kind of consider the 3.73 a bit more ideal than the 3.08's I had, or 4.10's. Just seems like a good compromise between economy and power.
And I don't want to have to rev it up to get moving.
This why I keep coming back to swapping the cam for something better suited to my truck.
~jp
SnoMan wrote:

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wrote:

Yes you are at a cross road, deeper gears for current cam and different cam better matched to your gearing. ----------------- The SnoMan www.thesnoman.com
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I wholeheartedly agree. However I'm going to try to make due.
I did finally talk to Edelbrock's tech support folks. They answered the question that has been bugging me: At what vacuum level do the rods pop up into Cruise Mode?
They said with my 4" springs, that the onset of Cruise mode should happen around 8" Hg of vacuum.
This pretty much coincides with what I have been observing on the vacuum gauge. While driving down the road, the lean spot is basically between 5" and 8" of vacuum. At 5", it isn't great, but it's really noticable around 5.5"-8".
Oh well... Gonna try to pick up a couple of sets of metering rods on the way home. Gonna get a set with the .068" cruise step. That should take it almost all the way back to stock cruise settings, even with my current jets (which are smaller than stock).
If this doesn't work, I'm going to go ahead and start cam shopping. Will I need to remove the heads to do that, or just the intake, rockers/rods/lifters, and any and everything else from the front of the truck?
~jp
SnoMan wrote:

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wrote:
Try a 6 or 6.5 inch power valve. You might also reduce the size of power valve to if possible. You may not find the fuel flow you need in main jets for smooth transition without being too rich at times. You could also try polishing the road with emery cloth to take a few thousandth of on them and tweak the flow a bit.

The SnoMan www.thesnoman.com
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Power valve? I thought Edelbrocks didn't have them!?
I did the following Google search: "power valve" site:edelbrock.com
Which searches the entire Edelbrock website for the exact phrase "power valve". I got one link in return, and it was in regards to an Edelbrock Q-Jet.
On a site, I found this: "Briefly though I can expound on a few things regarding how the "power mode" interacts with the main metering system, which I didn't think was explained well enough in the manual. I learned this information through trial and error and through talking to Edelbrock Technical Support. What they call the power mode is the same thing Holley accomplishes by using a power valve."
???
~jp
SnoMan wrote:

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wrote:

Got my carbs mixed up sorry. I do reacll that what I wound up doing with my Qjets was to use large jets and large metering rods so that they leaned out well at cruise butfattened up nicely with foot in it. Larger dia rods still have same min diameter at bottom of rod so a biiger rod in a bigger jet allows for lean cruise and more fuel when foot is in it. Maybe you should stick with 98's and find a larger diameter rod. It is a thought anyway. ----------------- The SnoMan www.thesnoman.com
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you should not have to go with smaller jets on a 600 CFM carb with a stock engine?
I use to run some various Holleys on a quasi hot-rod i had at one time. Mostly stock 350 , a holley 600 ran very well, later when added a completely different modified engine went to a 750.
I agree with your advice or whomever made the point about make small changes at the time. Seems like you would want to get your idle scquared away first.
I'm guessing on a stock engine that one or two jet sizes would be as much as even would make sense to do. I would think a 600CFM carb would power a stock small block just fine, without modification. As i recall a minor change in metering rod or jet size can really get you too much fuel when you can't handle it. YOu would need some steep gears to take the fuel if you changed it much at all as far as jets or I'm guessing this carb uses metering rods on the secondaries like a quadrajet? been a long time since I even thought about carbs.... but it would be nice to have an old school hot-rod to mess around with. I'm thinking that might be one of my future projects. ----------- Elbert snipped-for-privacy@me.com
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No metering rods on the Secondaries...just jets.
I admit I did go too far with the changing of the jets, and I need to make it richer on cruise mode.
I talked to Edelbrock's tech support yesterday. I wasn't thrilled with the results. The dude kept putting me on hold each time I'd ask a question. He'd come back 30 seconds later with the answer, so I don't feel confident that I was speaking with a real expert. Having done tech support and assisted with training, I can say that a good script to read from can allow newbie tech agents handle *most* calls. But this guy didn't seem to really know what was going on.
I don't know whether to agree or disagree with the statements he made about the gas fumes from the pipe. I haven't checked the plugs in a while, but he said that's the ONLY way to know if it's rich or lean. I disagree. Regardless of what the plugs look like, if you're gassing yourself and everyone within 100 yards of you truck to death with gas fumes, then you're rich!
I was gonna mess with it last night. I left work early to get to the local speed shop to get 2 sets of metering rods. They close at 5:30pm, and like Noon on Saturdays. Traffic was horrendous so I called ahead. I got there right at closing time--doors locked.
I called, got the same dude. Told him I was there and REALLY needed those metering rods. He said "hold on". I got put on hold, then transferred to somebody's voice mail, then automatically disconnected.
An hour and 45 minutes later I managed to fight through traffic to get home--with no A/C.
Needless to say, I was pissed off, hot and tired, and didn't feel like screwing with it.
Oh well...
~jp
Elbert wrote:

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