Terry, I read your post to Bobby about AX and Brian. Don't you believe I'm the guru of carbs? LOL.... I've done Edelbrocks with my eyes closed and did extensive research on the carb. I was determined to figure out how to adjust these carbs because everyone fears them. In fact,these are the easiest carbs to work on. Since your running rich! You'll have to drop some smaller jets in the carb. Taking the top off is no big deal. That's where you'll see the biggest difference. The needles and springs can be changed to fine tune the carb. It won't make big differences like the jets. Your running really rich my friend. I think you may be fine with the needle and spring combination you have. By what you tell me you have in your carb, I'm not surprised your getting 10 mpg. The 3.25 and 29.5 tires is fine. I'm running 2.75 gears and 28 inch tires on mine right now and am getting around 18 mpg around town. Email me if you have problems adjusting the carb. I'll walk you through it. In the meantime, put the .395 and .398 jets in and get rid of the .400. You'll see a hugh difference in performance and gas mileage. Trust me, I'm the guru!!!! LOL...

 

You're the man Ed!!!

I've had great luck with Edlebrock carbs over the years. With the advice you are giving I'm sure Terry is going to see some major improvements in driveability and efficiency in his truck.

Bobby

 

Hey Ed, I IN NO way ment to offend you . I just was asking Bobby, cause he's the first one I made friends with on this board. I do beleive you are the carb guru on here now. I REALLY APPRECIATE your offer. I will definately be P.M. ing you for help once I get started. As I said, I have an extra carb and took it apart to see how it comes apart and such. I dont know for sure that my carb has the "400's" I just took the other one apart, but they do have the same rods in them. As soon as I get my kit I'll talk to you more.

BTW whats the deal with adjusting the float level and the heighth of the metering rods? As I said I dont want to mess it up, at least it does run now.

Thanks man

 

I'm joking with you guys on the guru stuff. I just like to help when I can. I'm by no means a guru when it comes to carbs. As for the float level, it's very important. You remove the top of the carb, just like doing the jets. Flip it upside down and measure the distance between the float and the top of the carb. It's suppose to be 5/16". Edelbrock recommends taking a 5/16" drill and sliding it between the float and carb. That will get you very accurate. Make sure both floats arethe same. The height of the metering rod is determined by the springs. The metering rods activate by vacuum. When you start the engine, the vacuum sucks the rod into the jet, when you release vacuum, the spring raises the rod. Thus if you have a softer spring, it will lean the mixture slightly on idle and midrange. If it does have the punch, you'd want to put a slightly stiffer spring and maybe a little longer spring in to richen it up a bit. You can also mess with the accelerator pump on the right hand side of the carb where the linkage hooks up. There are three positions. The furthest from the carb is the most squirt of fuel to the carb. I usually run the middle postition and that works out best. Have fun buddy! LOL...

 

Hey Ed one more question, the extra carb I took apart, looks as if only one of the needle seat valve's is working? Am I missing something there or is there only one function needle and seat assembly? I thought maybe the other one was for if you had the fuel line comming on the other side?


I'm by no means a carb guy, but these things look really simple?

 

Terry, both needles need to be functioning. Sometimes the needle will bind, take that plate off that holds the needle down. Pull the needle out and see if any obstruction is there or maybe the spring is broken or missing. Put the needle back in and kinda bounce it up and down to make sure it moves freely. If it doesn't, something may be wrong with the needle or the jet below. It should move up and down freely. Ed.

 

OK, Ed, I forgot to ask you. Where are the rear jets? I easily found the front or primary jets when I took the top off, cause the metering rods go through them. BUT I didnt find the rear ones? As I said, I havent done much or any carb work before, but it really dont look that hard on this one. Please be patient with me cause of my lack of experience with carbs and THANKS agian! As I said, I dont have the top off of my real carb just the extra one so I dont know for sure what I have on my truck. YET.

Thanks again!!

 

Terry, the rear jets are to the rear of the carb. There is a partition in the fuel bowl that you can remove by using a needle nose pliers, simply pull that partition straight up. The jets are underneath that. You should be able see them even with the partition in place. It just makes it easier to remove them and put them back with the partition removed. Make sure you put them back the same way the came out. The rears are actually easier to get to then the primaries?? Don't get crazy, but the rear jets are smaller than the primaries. Example. Primaries should be .398 and the secondaries .395. Don't ask me why? It'll take to long to explain.

 

When Carter went out of the carb manufacturing business Edelbrock bought the manufacturing rights to the AFB Quadrajet (since many of E.'s intake manifolds were designed for that carb, they had a vested interest in it living on), it is basically the same carb.
It's been too long since I messed with carb much to remember the tuning specs, but Ed is well versed in them. Carbs ARE really pretty basic mechanically once you get them jetted properly. The best way to verify that the jetting is correct is to take it to someplace that has a chassis dyno and they can tell you what the Ox-fuel ratio is at various rpms and if not busy allow you to rejet between pulls (especially if the owner/tech happens to be a hot rodder). They can also tell you a lot more about the health of your engine and ignition system. Lacking that does your state require emissions testing? If so a testing station should have a tailpipe "sniffer" for pre OBD II cars that can also tell you the ratio, albeit only at idle.

 

Thanks AX, glad to see you back here!! My state dont have any kind of emissions testing anywhere so the only real reason I want to rejet is for the health of my engine and mpg's. It's a little late, since its been this way for 12 years anyway, I do appreciate all you guys help! I'll let you know more when I get my jets and start this process.





On a side note, I seen an ad on TV for E3 spark plugs. The ad looks impressive, but I've seen alot of hype on plugs. What do you guys think are they worth the cost? They are $6 each?

I also have to tune my distributor, when I built the truck, you could not get stock weights and springs for the HEI distributor so I put in a curve kit. It's been SO long since I did it, I cant remember which springs I have in it? I really need to tune it too. Who's the distributor guru on here?

 

Terry, stay away from "gimmick" plugs. (unless they're Bosch) IMHO

 

Raerjim is right. There really is no such thing as a super plug. Standard plugs work just fine especially for what you want them to do. Save your money.
On the distributor, it's often cheaper to buy a new distributor and ignition system then trying to diagnose what yours is doing. I've had a few distributors in the past that I had curved, etc and my performance got worse. I put a new distributor in and I was back to laying strips on the ground. (not on public streets of course, I would never do that!)

 

Jim, my recommendation for the diz is the same as for the carb, take the truck to a chassis dyno for a complete diagnosis and adjustment, should be < 100.00 for several pulls with cool down adjustment time in between and it will tell you what is going on thru the entire operating rpm range. It will pay for itself quickly in gas and engine wear and tear savings, well worth it!

 

Hey thanks guys, AX, there is NO place around here to do a dyno test so I'm on MY own. I think I'm just goin to keep it mild. The truck has run flawlessly for 12 years, it just gets lousy gas mileage and you cant stand to be behind it cause it runs rich. I'm just goin to mildly rejet it and check the springs on the advance weights. I'm not looking for spectacular differences, just a little improvement.

Thanks again!! guys!! P.S. which plugs do you guys recomend? I'm running an '88 model 305 chevy block with '85 model heads a RV cam(252 I think) HEI ignition, 600 CFM Carter manual choke 350 turbo, 3:25 gears and 29.5" tall tires, I also have a Edelbrock Performer intake.

Thanks again for all your patience!

 

For every 10 degree increase, chemical reactions will double (rough rule of thumb), so it makes sense to me that the cooler the better. I have had your same problems. If you run the math, a yblock such as mine should have about 339 cfm as I recall. All carbs in general can be too big. I had a carter and struggled with it on my 56 yblock. I now have a manual choke edelbrock leaned out to the max and its so much better.