i just did a full carb swap from my TBI system and new heads, intake ect. but im running a Edelbrock 1406 600cfm 4barr. temporarily (free from a friend)

i have a wideband hooked up and AFRs are fine at idle, cruise, heavy throttle, and WOT (once i get there) as soon as i go WOT the WB shoots to SUPER lean and the car almost stalls but if i "pump" from like 100% to 70% back to 100% a time or two it it will catch up and run fine at full throttle with good AFRs or sometimes if i just sit for a few seconds at WOT it will pick its self up.


im pretty new to carbs and still learning how to tune, is this a tuning issue or is something not working right??

Thanks!

 

That is definately an accelerator pump issue. I know jack about edelbrock carbs so maybe someone with some experience here can chime in.

 

It's the secondary air valve opening too quickly. It's not adjustable.

Where's your ignition timing set? What distributor are you using?

 

well my timing on the crank is off from the actual timing so im close to 0 or a little bit advanced for base timing i have an MSD dist. with mag pick up with Vac adv. and Mech adv. (both set to out of the package settings) run by my 6al

 

Before you touch anything on the carb, get that ignition timing sorted out. If you've converted from EFI to a carb that means you're also running a non-computer-controlled distributor now (right?). You'll want about 12* base/initial timing (with the vacuum advance disconnected) to get you in the ballpark for a street performance application. A lot more than the factory TBI base timing. If you're down around 0* BTDC on the base/initial timing you'll be shocked how much better it runs with another ~10* or so of advance dialed in.

ALWAYS do ignition timing first before you mess with the carb. Remember the old mechanic's rule that 90% of carburetor problems are found in the ignition!

 

How can i set the timing to around 12*s without being able to use the crank as reference?? im new to none computer controlled anything i've only done computer based tuning before

Thanks!!

 

I assume you have a different damper than original, or different timing tab (front cover). If that's the case, and they are of different type, you need to get a piston stop and go through the process of finding TDC and marking your damper to the timing tab accordingly.

 

For what i did i got a timing light out then loosened the little bracket on the disributor bolted on the engine and with the engine running i just turned the dist. till the timing light said i was at the right spot. And an easy way i do for top dead center(tdc) is to take cylinder number one's spark plug out and crack the engine about one click and if you feel compression out the whole of the spark plug with your finger or just take the valve cover's off and see if your springs are both up. but for the testing of tdc just make sure you take the wires out of the dist. woudn't want the engine starting when you were testing that.

Hope that helps?

 

That's not finding TDC, that's finding the #1 firing position.

 

ok well im hoping that my fuel pressure was just too low, i raised it at my AFPR and it seemed to help (havnt had time to really play with it though) but either way i want to reset my timing to were it will match up

How do you use the piston stop?? from my understanding u just put it in and turn on compress stroke until it stops... but how do you find TDC then?

sorry im such a noob but
Thanks for the help!!