Hey guys, been a while since I've been able to post anything up here since our training schedule is crazy at work(army). I need some help to get my carb tuned better than what I have. I have an Edelbrock 1406 and yes I do regret buying it but for now I need to get this running as best as possible until I have the money to buy a better Holley.

I'm getting really lousy mpg and I'm not really sure why since I'm sure there are several contributors. I've got the carb tuned as best as I can by ear without having a finished exhuast(no money left until jan). I have an Edelbrock 1406 that I bought from ebay and rebuilt with a rebuild kit. I wish that I had thought to get the numbers off the jets that are in it so that I could see where it is at currently.

I also don't have vacuum hooked up to my HEI yet since I'm not sure which port to hook up to, or how much advance to put on it. The only advance that I have right now is from the springs inside, and I can't remember what my base timing is right now. As soon as I find out where I put my timing light I'll find that out and post that up as well. I know that this engine is not set where it should be so I'm just asking for a little help so that I can get it done cheaply since no-one around here remembers how to work on carbs.

I finally got the electric choke hooked up so I'm sure that's going to take some time to get that set right too with winter settling in around here.

By lousy - I mean that I'm getting about 10-11mpg

I would really appreciate any input so that I can get more done on the car before monday. Thanks!!

 

Hey, dont bash the 1406- Ive had 6 and loved every one. As far as the MPG and Vacuum, I would suggest that you hook the short port (on the left of the carb as you are looking at it) to the distributor. That is the "timed" port, meaning that it only gets vacuum at throttle, not idle- so you dont have advenced timing at a stop but achive it at around 2000 RPMs. Another thing to consider is the accelerator pump, on the front right side of the carb. If the plunger is set at the bottom hole, you might be pushing in too much fuel. Check it, should be in the middle or top for a mild 350. If you pull out the rods, the numbers stamped on them correspond to the diameter of the rod, i.e.: 7445 is .075 inches for the second stage and .045" for the primary. the jet also has a number stamped on the top, like 101 which is .101". You should have around a 98 or 99 jet and a 7645 rod for a mild 350, but these numbers aren't magic. Another thing to look at is your emissions setup and what else you have running off the engine. Hope this helps,

 

To tune the carb ...

Make sure all vacuum ports are capped or connected where they should be - big on on rear to brake booster, big one on front to PCV valve in valve cover. That leaves the two small ones on front - cap the one your not testing.

Get a vacuum guage, cap the right port, plug guage to the left port, then adjust the left screw in and out until you get the most vacuum you can. Then plug the left port, and vacuum guage the right port, and adjust right screw to get most vacuum you can. Then, adjust left screw to see if you can get anymore vacuum. Then, cap right port and guage left port again, but adjust right screw to see if you can get anymore vacuum.

Then, you are tuned. Plug right port, and run a vacuum line from left port to distributor, and that should be it.

Depending on rear gears and whether or not you've got a lockup rigged for the torque converter, you should get closer to 17mpg. I'm getting 17 on mine setup as below.

For the choke - see the instructions at Edelbrocks website - it's pretty easy. There will be better tuning instructions to download there too - but my method will get you going.

Some bash them, but the Edelbrocks are good, easy, reliable carbs. The Holleys are easier to change jets and such on, but they are built that way for the track - can't beat the ease and reliability of an Edelbrock on the street. I haven't had to touch mine in over 2 years, always runs good.

 

It's not really that I mean to bash the Edelbrock's, I know that they can be good and reliable for stock to mild engines, I'm just having problems with mine since I bought it used. Then to top it off it's been a very long time since I've done any carb tuning so I don't remember much about tuning them or the ignition by ear.

While I was waiting for anyone to reply I was out in the garage trying to get my pressure regulator mounted in the car so that I could be sure that I'm not getting more pressure than I need to the carb. I got it in but since our other vehicle was right outside the door I decided to leave setting the pressure for tomorrow. I'll probably set it for 5ish once I reread the instructions for the carb.

I'll be sure to hook up the vac advance to the left port, I just have to get some vac lines for that. I'll have to get the MSD instructions too so that I can get the vac advance set too. I advance it a degree or two at a time until I start hear pinging...right? (that would be so much easier with a car that wasn't so loud, lol)

I will try to remember to get the rod numbers at least. To get the jet size I have to pull the top of the carb back off again right? I really don't want to do that.

I don't remember which spot I put the plunger in, I think it was the center hole but I can't remember for sure. I'll set it to the leanest setting now that I understand that part of it.

I have no emissions on this thing, I wanted to run it as stripped as possible.

I appreciate the tuning guide camaro... I used that method sorta when tuning it when I first dropped it in, but had to change it since then(don't remember why). When I did it last time I think I had the booster line on as well as the PVC, and I'm not really sure which side I was on but I didn't change ports when I did the whole thing. Isn't one port vac above a certain RPM and the other vac at all times?

How much will not having mufflers on the car effect the tuning of the carb and ignition? I'm sure I'll have to go back and retune it once I'm done, but I don't think that no exhuast will cause this much trouble. And yes I will get it done, I'm just broke until Jan 1st. Hopefully I can get all this done by the time I get my clothing allowance at EOM Jan or Feb paychecks. So far I have Hedman shorties with dual 3" following the stock routing until I get's to the driveshaft under the passenger seat.

Thanks

 

hi , i have a 1405 and it's good...but i bought it new and basically bolted it right on and with minor adjustments ....it runs well...you should go to edelbrock.com....they have instrctional and helpful tips on how to install--tune ..re-jet etc and make the edelbrock carbs run at their best ...good luck.

 

Hook up the vacuum advance. It's there to improve fuel economy.

Set the initial timing at 12 degrees BTDC without the vacuum advance connected.

 

I have the vac advance hooked up now, although I have it out only two turns, can anyone help me to read this? http://www.street-fire.com/8362.pdf

I have verified that my plunger for the accel pump is on the center setting so as soon as I have time I'll change that to the top to try to reduce the fuel used.

I did use my vac guage again and set the mixture screws and the timing to the best readings. I still don't know where my timing light is so I'm not really sure where it is set at. After adjusting both for smoothness and highest vac I got it to 20in vac at idle, not sure how good that is in general, but that's the best I could get this motor to.

How much will vacuum change in the manifold when I do get the exhuast finished? A lot? or just at little?

 

You've got to have the timing set correctly. If it isn't, you can't expect the engine to run properly.

How much of the exhaust are you missing now?

 

The exhuast was removed when I put this motor in and I have just not had the money to finish it with the holiday and birthdays getting in the way. Right now it's run dual pipes to under the passenger seat right where it comes back to the driveshaft. I'm hoping that I can get the rest of it finished soon.

 

Very little if any effect on intake vacuum, then.

 

I changed the accel pump to what looks like the leanest setting, hopefully it will do some good since it doesn't look like the things that I have done so far have done nothing to improve the MPG. It really looks like I'm going to have to take the top off this carb to get at the jet and also look at the hanger so that I can at least see where on the chart this carb is sitting.

 

The accelerator pump isn't going to have a significant effect on MPG. It only operates when the throttle is being opened. If you aren't having any stumble problems when opening the throttle, then having it on the lean setting is fine.

Have you done any rod changes yet? One "pro" of the Performer carb is the relative ease of tuning via rod changes. Of course, when you can't tune any further with rod changes, you have to go to jet changes, but that's usually a big step.

 

I know that the accel pump wouldn't have that much effect on the mpg, but it's something that I could try. Of course I did that last night and since driving it today I've noticed a little stumble every now and then, but I'll drive it some more. If it is worse, or happens more often I'll change it back to the center position.

As far as the rods, I haven't pulled them up yet and I haven't pulled the top of the carb to see what size jets I have in the bottome. Is the jet size stamped on the top of the jet where it would be visible without fully removing it? Or is stamped on the side?

I'm not sure if it really did as much as I think, but when I changed timing I've since noticed a harder time starting it sometimes and overheating under acceleration or above 2k. As long as I'm idling it'll run cool, otherwise it'll climb all the way up to 260 if I can't idle it. I don't think ignition timing would effect the lean/rich effect or egnine temp, but I figured I'd mention it just to be sure.

I figure I'll give the new accel pump setting a day or two longer 'testing' just to see it if will continue to stumble, or if it was something else that caused it. I'll wait to check the rod numbers and jet numbers sometime, probably till when I have to change the accel pump setting again.

 

The overheating could be caused by excessive advance in your timing. If the cylinder fires too far before top dead center, you are causing more friction (thus heat) in the engine. Make sure your base timing is set for no more than 12* BTDC. I time mine at 10, but that is more for longevity and tunability than for power or economy. Your distributor could also be throwing the timing off if you have changed the weight springs for lighter ones, or set the advance too high. Make sure your base timing (without the dist. plugged in) is around 8-12, and then verify that it does not jump when you plug the dist. back in. If your total advance is more than 22* for a mild motor, you may have the overheating problem, but with hard starts I'd say that your initial timing is too far advanced.

The main jet (and secondary for that matter) diameter number is stamped on the top of the jet, and is visable with just the upper housing of the carb removed. You may need a magnifing glass to see it clearly, or just remove it. Use the calibrations chart from edelbrock to get your air fuel ratio right, those charts are a huge time saver. Hope this helps,

 

I've actually been suspecting this for a bit, but more to the over advanced condition causing excessive burn time in the cylinder which would cause overheating as well. I just wanted someone to confirm what I was thinking, thank you. I had to use christmas money from my family to get a timing light last night, so hopefully I can find some time today to get to the timing and to get into the carburetor. I will have to reduce idle to below 800 rpm so that I can be sure that the stock springs in the distributor don't start working, which by the way are still stock. The hard starting is usually just for a couple cranks and then it spins normally.

I know the charts are there, but without knowing what I have for jets and rods in the carb the chart doesn't do me much good. I just hope that I don't have to replace the gasket just because I pull the top off the carb.

As far as the accel pump, while paying close attention to the engine I've still noticed slight stumbling so I'll change that back to the center position, just to get rid of that. I have noticed that I've gotten slightly better mpg, but I'm really thinking that I'm going to have to start changing rods and jets to get it where it needs to be.

Edit:

I'll be really happy when I can get the rest of the money I need to finish the exhuast. I won't be able to get the carb done right if I can't hear the rest of the engine, or the timing for that matter. Unfortunately that won't be until the beginning of January.

 

Overheating is usually caused by retarded timing, not overly advanced timing.

 

Well, as I suspected, my timing was WAY off. So far off that I could not see the timing mark until I turned the distributor a bit. I now have it set at 12*, and by guess should not be more than 22* with vac advance. Of course the only way to really tell is to put some timing tape on, but I really don't feel like pulling off the front of the engine just to put some of that on.

I also pulled the top of the carburetor off and took a look at the rods and jets. According to the Edelbrock owners manual, both rod and jet are stock (.075/.045) and (.098) respectively. Which would be better, 1 stage leaner or 2 stages leaner?

I am still having a problem with the engine running hot under acceleration though. I noticed a little dirt/junk in the bottom of the bowl on the driver's side, I'm wondering if something got stuck further in the circuit and causing it to lean out. Does anyone have any other ideas that might cause this hot problem? If it is what I think it might be, does anyone have any idea how to fix it? I had the idea of using compressed air through the main and secondary jets to try to flush any junk out.

Thanks

 

Which would be better, 1 stage leaner or 2 stages leaner?

Does anyone have any other ideas that might cause this hot problem?

Edit:
Did my math from the refuel yesterday and I'm still only getting 10.1 mpg.

 

http://www.edelbrock.com/automotive_...ers_manual.pdf

I'm thinking of getting the jets for the #7 and #10 on page 13, and stage 2 and 3 lean on the secondary mains. I'm hoping that these will fix my problem, or at least get me better mpg.

I do have a question that I hope someone here can answer or at least will answer...do the jets and hangers for the smaller carbs still fit in the larger ones? I would assume yes, I just want to be sure.

 

I've ordered the jets and rods for #7 and #11 in the instruction manual, that should give me a good start in the direction that I need to go. Hopefully I'll be able to get this thing running right soon after the new year.

 

Concerning your overheating issue, what have you done in checking your cooling system? Does your car overheat from normal driving around or only wide open throttle? Are your hoses old and possible collapsing under hard acceleration?

Another question that I believe was asked but never answered was if you have a lock up converter and if it is working properly.

 

I have converted to a manual transmission. I was having a problem with the overheating during acceleration or rpm's any higher than the idle circuit. I haven't noticed that much lately since the first drive after opening the top of the carb up, but I also haven't had the car out much other than the short 3 mile drive to work.

Edit: hoses haven't been collapsing, that was one of the first things that I checked, as well as fluid level.

 

I hadn't taken the car for a long drive since I've been trying to work on the carb to get the overheating to go away. Took a drive yesterday and it was overheating again, I can't go 60 without it trying to overheat. Going 70 is completely out of the question too. Whatever the problem is, it is in the mid to full throttle area. I still think that it may be some junk caught somewhere in the fuel circuit, either for the mains or the secondaries.

 

This may be stupid, but it came to mind.

Is the overheating occuring at a certain throttle position (ie RPM range), or is it happening at a certain physical car speed?

I guess what I'm getting at is - do you have the air dam under the car for the highway speed cooling? Without it, all of our cars overheat at highway speeds.

So, was kinda a stupid question, not related to the tuning - but was my first thought when you mentioned overheating at 60-70 mph.

 

I've have part of it on, but not all of it. I serisouly doubt that is the problem since I've had that off for a ver long time, this has only been recent. I said 60-70 because I don't drive it any faster than 75, maybe I'm old but I really don't feel like getting speeding tickets anymore. Besides I had the old 305 running the same way. When it all boils down the only thing that was changed has been induction. I think I'm going to have to just take carb back off and clean it out again, and see if there's a way to clean the circuits better than I did last time.

 

Well yesterday when I was driving out to the in-laws house I went the back roads and didnt' notice any overheating, so I didn't think about much, but I drove home using the interstate instead and that's when I noticed the overheating again. When I'm not doing a steady state pace 60, like through the twists of back country roads, that is when I'm not overheating. But when I'm staying on a straight road that is when I'm having problems with the overheating.

 

Well your overheating could be several things. Could be a thermostat sticking shut, could be your water passeges being clogged. The guy that had my car before me put a new water pump on it and caked it with silicone so when I took the pump off looking for my overheating problem I found smaller-than a dime sized passages on both sides of the pump. As for your crappy gas mileage I couldn't really contribute to that..I have a 1406 and I get 26mpg highway so...

As for Blind Driver are you actually gonna contribute anything useful?

 

It's a brand new water pump, and the engine was cooling just fine at speed and under acceleration just fine when I first put the engine in. I'm going to have to put a filter in right before the carb, I thought that the stock filter would be fine but it seems I was wrong with the junk I saw in the bottom of the carb bowls.

edit: it has a brand new thermostat too. Thanks for the mpg number on yours, can you tell me what you have in your carb(jets and rods) and what you have in your motor?

 

I've had enough of crap with this thing. I bought a Holley 80670 Street Avenger 670CFM w/electric choke last night, along with a pair of sight plugs and a Holley tuning book. All the external stuff put the cost over $500, jeez. Anyone happy or unhappy with this carb?