leaner jets- hopefully my mileage improves now

blackagatha · Post by **blackagatha** » March 2, 2008, 7:34 pm

I just swapped the jets on my carter 625... Was getting 8-9 mpg. Today it somehow made 10... I was driving at a liesurely pace on a local highway, probably 40 mph, fewer stops than normal.

Anyway, I took out the .120 jets (same on primary and secondary circuits) and swapped in some .092s, with real fat rods (dont know what size) that I put in previously. It runs good.... at Least as strong as before, probably a bit less stink now. Hopefully a lot better MPGs.

OH, I should mention, I found a basic owners manual for the edelbrock/carters on edelbrock.com. good info in there.

MadMaxetc · Post by **MadMaxetc** » March 3, 2008, 6:29 pm

I need to do the same.

I checked mine the other day...down to 13mpg (was 17-18) but I think that has to do with the 5 min warm up I had to do every day because of the ice & snow.

I think I am going to go dow 2 steps.

blackagatha · Post by **blackagatha** » March 3, 2008, 9:53 pm

you seem to know more about this than I do, with steps and such. I just found some jets that looked a lot tighter and still fit around the rods. It still seems to run ok so I must have done ok?

blackagatha · Post by **blackagatha** » March 5, 2008, 1:09 am

maybe its too lean? it still seems to run decent but pops under acceleration, feels kinda weak accel thru about 30... DOES ANYBODY KNOW what would be a good jet/metering rod combo for a Carter (edelbrock) 625 on a 390?

My65 · Post by **My65** » March 5, 2008, 11:25 am

You can email Edelbrock with your carb model (size), engine make, size and year, and your elevation above sea level and they will tell you what is the optimum combo for you.

jakdad · Post by **jakdad** » March 5, 2008, 12:01 pm

The AFBs are easy to work on but never did to well on milage or performance.

blackagatha · Post by **blackagatha** » March 5, 2008, 7:57 pm

fact is, AFB/edelbrock guys and Holley guys have been duking it out forever, and I'm sure they'll continue.

I like my AFB, it has been getting terrible mileage, but as I knew NOTHING about properly tuning. I downloaded an owner's manual from edelbrock.com, and set the rods and jets for the leanest charted setting. (I guessed I might have something comparable to the 1405 carb), and the #27 plot is 10% lean on power, 12% lean on cruise.

I had put in some .092 jets the other day, apparently off the chart lean. She was runnin like hell during acceleration, but smoothed out at steady throttle.

I richened it back up a tad, but the leanest plot on charted territory.

Runs incredibly well actually, I accidentally squeaked my tires at a stoplight, straight and level on asphalt. In the past this has been Almost impossible, with the 2.75 rear installed.

MadMaxetc · Post by **MadMaxetc** » March 5, 2008, 8:50 pm

remember that there are Jets and Metering Rods.

check out there wesite and you can get a manual (pdf) that will show you the propper tune.

shawns fords · Post by **shawns fords** » March 5, 2008, 8:59 pm

I rn one on my 67 for a long long time, back then you could buy a Strip kit from super shops for 15 bucks, I tried to buy one a couple of years ago from local parts house, the Edelbrock kit is now 65-70 bucks. so I went to swap meet bought a holley for 10, rebuild kit for 22 and went on my way, gave the Edel to a buddy who needed one for wifes van, the old strip kit and everything. Dad runs one on his cuda also, it works great. He Called Edelbrock in, they gave him the correct calibration Jets and rods to replace. he went with that for a baseline. then fine tuned it to perfection. He obviously has alot more time than I do rofl. I could never seem to get rid of a " dead spot" weather it was on accelleration, or on cruise. it was always somewhere in there whichever way I adjusted it. so many combinations its alot of work to get a perfect tune, but once its there you never have anymore troubles. Anyways enough blah blah blah. good thing your where the air is good, up here there can be elevation changes from 6800 feet to 11,000 in a matter of a couple of hours

My65 · Post by **My65** » March 5, 2008, 11:01 pm

Like I said, just email them directly, and they will tell you what to put in. Make sure you give them your elvation above sea level.
On a side note, I have never had a Holley run right no matter what. The Eddy I have now tho, I get @ 20 Mpg carrying 2 engines and 2 trannies (@1500 Lbs). That is with 3.73 gears and a C-6!

shawns fords · Post by **shawns fords** » March 5, 2008, 11:24 pm

Off topic but, not much to do to a holley. I dont know why you couldnt get it to work. Set the floats, size your jets, adjust your idle mixture, and go baby go!

blackagatha · Post by **blackagatha** » March 5, 2008, 11:44 pm

My65 wrote:The Eddy I have now tho, I get @ 20 Mpg carrying 2 engines and 2 trannies (@1500 Lbs). That is with 3.73 gears and a C-6!

what engine, what metering rods/jets?

My65 · Post by **My65** » March 6, 2008, 6:19 pm

I don't remember what rods and jets, but they feed a 351 Windsor and flow out dual 2.5" exhaust. Make sure you tell them the elevation. That sounds trivial, and yes you can run the same rods and jets from 3500 feet down to sea level, however there is a huge difference in perfomance.

blackagatha · Post by **blackagatha** » March 6, 2008, 10:01 pm

My65 wrote:yes you can run the same rods and jets from 3500 feet down to sea level, however there is a huge difference in perfomance.

oh sure... of course... I guess it's good that I got some pretty tight rods in there, so I could easily swap in richer rods as I go down the big hill...

SOMEDAY, I would like to get EFI, maybe one of those fake carburetor types... then I wouldnt have to worry about it...

My65 · Post by **My65** » March 6, 2008, 11:06 pm

Smarta$$

What I so ineloquently meant to say is that you can run any carb right out of the box with no changes. Problem is tho, that if you are not at sea level, you will be running either rich or lean. Also because that same carb is made for all brands and Cubic Inches, there are a lot of factors to take into consideration. The easiest was for me to email them, tell them all my details and let them tell me what I needed. They didn't even ask me if I had AC or the color of my valve covers!!!

Once I put the recomended parts in, she ran like new. Runs and sounds better than it did with all the EFI and 'smog' crap on it. (I took all that off) The only other mod to the engine was a set of Crane roller rockers. Even at @ 20mpg it is still running a little rich I think. However I heard the newer ('80 and up) engines prefer rich to lean...

blackagatha · Post by **blackagatha** » March 7, 2008, 12:01 am

Well, I think anything probably prefers the rich side of the mixture curve. It's really obvious in small airplanes.

We lean the mixture during cruise, using the exhaust gas temperature guage. We pull it back to peak EGT, then push it 50 degrees richer than that. You can get the same temperature by pulling it leaner, but it is not nearly as uumphy as when rich. Granted if you were running out of gas, it would be an obvious solution, as it still runs ok, but when you advance the throttle it acts crappy... HELL, just like Aggie was when I had her too lean the other day... Acted fine while at a steady state, but give her the goose and she didnt like it... I got her back into a nice range and she's running SWEET. MUCH less stink, quicker takeoff, and I would think at least a few more HP. Just a tad easier to squeak the tires now. I havent tried to powerbrake her, but I bet I could lay out a decent peel right now... If I had the 3.89s in the rear, I could probably lay out 20 feet or so... Maybe I'm givin the old girl too much credit, but she feels better than she ever has...

And I fixed my damn shifter tonight, it's been a pain ever since I installed it. Not sure why I never messed with it till tonight.

The Park position was so far forward (my C6 has a clamp-on type lever that you can move) that it was at the very front of the arc, and the linkage wasnt able to hold it UP, when I pump the gas to start her, the kickdown would hit the shift lever and momentarily throw her out of park, and she would roll.
I took the bracket out, a chunk of lawnmower blade (that thing was a BITCH to drill a 1/4 inch hole in- we didnt have a 3/4 drill bit, and needed a 3/4 hole) attached to a chunk of angle iron... Was made with no adjustability. WTF was I thinking when I made it? I slotted the holes in the angle and pulled it back about an inch. MAN, does it shift nice now.... I'm happy. I've gotten 2 major LONG-TIME issues squared away...

Now I wish I had the cash to make some of my fantasies come true... I would be working my ass off every night on her, doin the suspension mods, doing my fabled chop stretch convertable mod, but Im away from home and little cash, so crack...

My65 · Post by **My65** » March 7, 2008, 11:19 am

blackagatha wrote:Now I wish I had the cash to make some of my fantasies come true... I would be working my ass off every night on her,

Mmmmm, makes me think of Danica Patrick....

Too bad you weren't closer. You sound like my own "Redneck fab shop".

Johnny Canuck · Post by **Johnny Canuck** » March 7, 2008, 11:44 am

My65 wrote:
blackagatha wrote:Now I wish I had the cash to make some of my fantasies come true... I would be working my ass off every night on her,
Mmmmm, makes me think of Danica Patrick....

blackagatha · Post by **blackagatha** » March 7, 2008, 6:29 pm

Johnny Canuck wrote:

LMAO JC, Whaat the hell? HAHAHA

Too bad you weren't closer. You sound like my own "Redneck fab shop".

haha huh? whatchoo mean? I try to avoid the redneckery on my truck... but yeah, I tend to be a bit red in my shop practices... Like our toxic waste zone in the backyard.... MOST of the used oil goes to the collection place, but a large amount goes on the ground next to the can.

Most rotten gas gets used to wash rags and/or the floor of the garage. Some gets thrown out on the ground.

You know... the EPA would probably have a fit if they came to the garage...