(81, stock 350, 2701 performer intake, 1406 EB carb, New MSD "ready to run" distributor, new plugs, new plug wires, true dual exhaust, no cat, or computer)

Finally got the intake and New Carb reinstalled. After giving up on the 750cfm EB carb, I ordered the 600 cfm. Put it on, set timing, adjusted A/F, and it's the same crap.......This thing is acting just like the bigger carb. Changed springs 3 times playing with the timing, to no avail. Dang think acts like it's not getting enough gas. I noticed while driving with my A/F meter hooked up that it back fired when I got on it, and it was leaned out.....Haven't tried rod/jet/spring change yet in carb, but I've been this route with the other carb.

Timing: 16* initial at idle, 34* initial with vac attached at idle, and I'm getting 36 in before 3000 rpm depending on which springs I have in without vac. The middle springs want to run the best.

I can't find any vac leaks, timing seems correct, new fuel filter, new air filter, new gas hoses. Could this be a vapor lock problem? My gas hose is right on top of my valve covers and it get pretty warm to the touch.

Other notes: I can set the carb up steady on the A/F in garage at idle, but it's all over the place while driving. Will read 13 at partial or no throttle, then you get on it a little and it leans out, then catches up as the throttle is continued to be opened.

I tried spring changes, pump shot change, and all that with the other carb, and don't want to waste my time....

Fuel delivery problem is what I'm thinking.....any thoughts??

Oh....I took the banjo fitting off because it was leaking and put on the stock fitting, When I did, that boy had alot of pressure on it. I even popped the gas cap first. Seemed like alot of air mixed in with the gas......

 

Did you change out the stock distributor????

Barry

 

Yep, new MSD distributor.....forgot about that...and new plugs and wires....I'll add that to the top....

 

hey brian,
ok man, going bad lean agen? it's do'n the same thing, it's time to look at the other things, hate to throw parts at it, may be a bad fuel pump like you mechanic told you before? or maybe a bad sock in the tank or it's come'n off? when you get'n on it sock get'n in the way of fuel?
maybe look over them lines one more time, back when your Half Shaft let go you may have a bent line back there some were that you did'nt see. was do'n good tell then was'nt it?

 

Shoulda bought a Holleyyyyy......

Brett

 

Double teamed by the south Jackson boys....imagine that.

Test run two: I rodded richer, change springs in the carb for higher vac, and adjusted pump shot......Ran alot better. Similar to other carb. Had to jet/rod richer to get it out of the hole. Ran okay, but doesn't want to get out of the hole. Held the brake, and barely got a squeak out of the tires.....

Still think I need to go richer......why is this? After the carb catches up when stepping on it, it will lay you back in the seat.......Sometimes it's also non-responsive at higher speeds when getting on the gas...it's like there are lean/dead spots.

Done for the day, will play some more tomorrow.....It was fun to get out and drive for a change!!

 

just try'n to give ya a hand my frend not a easy thing over the net.
glad you get'n worked out

 

You and Brett better come early to the crawfish boil Saturday! I'm gonna just toss ya the keys, and you can't come out and have crawfish and beer until she's running right!

Any other vette boys in the area are invited as well, but gotta bring your ride! PM me for more info.....

Hey, maybe that will work.....tuning for crawfish and beer, I supply, you fix!!

 

Calling all Texas and Louisiana vette wrenchers...FREE BEER and BUGS in MS. Have tools will travel!

 

There was a thread a small while back that gave some ideas for getting a 1406 to work better. Look in the manual at the base settings for the 1405 carb, it's 600 cfm just like the 1406, but it is jetted richer. Jet and rod your 1406 using the base calibration for the 1405 and see what happens. I'm also running a 1406 on top of a Performer RPM and when I made that change, life got good!

 

I'll check into that....thanks

 

Come on.........we have plenty. Just remember, no crawfish or beer until the baby is running properly!

 

ttt.....HELP!!

 

have you tested the fuel pump for delivery? disconnect fuel line from the carb, take out spark plugs, ground coil get a bucket and crank for one minute and then measure the fuel you have in the bucket.

 

I'm going to get to the bottom of this! Here's letter I emailed Edelbrock Tech support, after being put on old for 15 minutes with no answer over the phone......


To: Edelbrock Tech
RE: Carb issues with 1406 and 1411

I have recently purchase two carbs....1411 and 1406 and can't get either to run properly on my car.

Car history: 1981, Corvette, stock 350 engine, true dual exhaust, no cat, no smog, no computer. New MSD distrib., new plugs, new plug wires, new EB 2701 intake, new EB fuel filter, and motor was overhauled by previous owner 4 years ago.

Timing is not an issue, and I have played with various settings. Lean conditions have caused hot running motor which didn't exist before any changes made.

Stock mechanical fuel pump, new EB fuel filter, new rubber gas line to carb.

Had the car running good with previous setup with stock intake, old non computer Qjet, and new MSD distrib. It would get out the hole very well and had good front end power.

I have checked for vac leaks (none), I have reinstalled intake for a second time to make sure it was sealed properly, and have ruled out most everything except the actual carb, and possible fuel delivery problem. I put on a 5.5 gas press. regulator, it made no difference and is now removed.

Problems are similar and exist for both the larger carb, and the small cfm carb. I have an A/F meter hooked up to verify rich/lean. My at idle vac is 15". Vac is hooked to manifold vac.

I am presently working with the 1406 carb. The stock setting ran very poorly. Very inconsistent A/F readings, though somewhat stable at idle. Meter would lean out on initial throttle, then at partial, fairly steady at WOT. Cruise was steady. (Cruise is not an issue). Would not get out of the hole, would backfire, and lack power. I changed to #23 on calibration chart with limited success. Car did run better and was more responsive. Still doesn't want to get out of the hole very well. A/F readings were more stable. It feels like a catch up situation with the carb. In this setup carb would barely trickle into the rich mode on A/F at idle, and was running around 14 at cruise, but would still go lean in spots. Adjusted springs to plain, and pump shot to highest hole. Made very little difference. Idle Mix screws like to be turned rich and have little affect after backing down, then coming back up initially.

I went through these same issues with the 1411 carb, and almost identical comparison. I actually took the 1411 to #23 on the charts with same results. Hopefully you can help......Please call if needed

 

i'm waiting to see this fix

 

it sure sounds like a fuel delivery problem.
bad pump, or some'm block'n the fuel in the line, bent-up line or bad sock in the tank.
what ever it turn's out to be, it's got to be some'm in common with both setup's.


yeah, let us know what the Edelbrock Tech has to say.

 

Sounds like a problem with the accelerator pump to me. The pump should give you a very brief Rich signal on the AF gauge when you poke the gas while driving. Maybe the linkage(s) are not set right or the pump is not pumping when it is in the initial part of its stroke.
The MSD vac advance worked okay with the Qjet and was probably at ported manifold vacuum but maybe now you have it on manifold vac and that makes the vac advance go away much quicker when you poke the throttle. Is the distributor end play set about 15 thou? The Accel distributor I bought was at 80 thou and their tech guy confirmed that was not right so I had to shim it myself.

 

9 hrs later....no reply from Edelbrock yet......It's funny on their recording when you call and wait....and wait....you here what great customers service they spout off as having....

 

I was having fuel delivery issues that REALLy only showed up at WOT at the track. I changed to electric fuel pump after I found my fuel pump pushrod was bent. I could've just changed the rod, but wasn't sure if that part of the cam was damaged.

Matt Gruber offered a good idea: plumb in a test fuel pressure guage, and tape it to the windshield. Watch it under WOT. If it falls below 5 PSI, you have a fuel starvation issue.