71 Elky with 350,Isky 292 cam,750dp.Car runs fine at idle and throughout all rpms, but when I mash the throttle from idle it dies.I thought it was only because it wasn't warmed up,but it does it when it's warmed up too.Heck, if I'm lucky it will slightly backfire through the carb.Tommorow, I'm going to check the timing and go from there.The floats are adjusted correctly and the mixture screws are also correct.Any other ideas before I get started? Thanks

It's too lean. You need a larger accel. pump shot. Try upgrading the squirter first.

First Check to make sure you are getting a pump shot. With the engine off, look down the throttle bores and operate the throttle crank by hand. You should see fuel being squirted into your engine. If not, investigate why your accelerator pump isn't pumping. Could be a cracked diaphram.

Troy.

I checked the squirter and it's definitily squirting.When you say that it's too lean are you actually refering to the idle mixture screws,or do you just mean that I need a bigger shot a fuel in the carb from the squirter? I never did check my timing, somehow my timing light is broke.

change the accelerator pum from the 31cc to a 50cc the kit is like 45 bucks . maybe your carb is to small?

If your timing is right then the pumps need to be tuned. Make sure you have the right clearances on each one. With the engine running, in park, crack the throttle by hand half way or so and release. If it stumbles go up in squirter til it stops. If it does not stumble with this test, the squirter could be fine but the pump cam needs to be changed. After working out the front squirter, move to the rear. What I have found to work here is to get in the car, engine running in park, mash the peddle to the floor and let up as fast as you can. Now use the steps from the fist test to tune the rear pump. This will get you close to right and save time on the in gear tuning. The tighter the converter and higher the rear end gear the harder it will be to get it dead on. Don't waste time on this til you get the timing right.

Check the mechanical advance weights and springs to make sure they can move smoothly. They need to be kept clean and lubed (do not use grease).

I ran into a similar problem to this on a friends Camaro. We changed jets, squirters, pump cams and finally put on a different carb. Still had the same problem. It had a brand new HEI dist in but I decided to check the magnetic pickup anyways and after I pulled it off I noticed one of the wires coming out of it seemed "sloppy/loose" and the tag on the bottom of the pickup read "Made in Indonesia"...hmmmm. I installed a Borg Warner pickup and it cured the problem. It was a night and day difference when you hit the throttle, no hesitation. The back fire through the carb can either mean a very lean condition or an ignition problem. Would also be a good idea to just simply check the timing, it may be to far retarded.

Most problems with the carb are not carb problems. Check the entire igniton system, advance curve. Make double damn sure it's right, then look to the carb. If the car has worked fine in the past and has developed this issue, a bigger pump shot via cam change, squirter size or god forbid......bigger pumps, is gonna take you so far off track you'll be looking to score a new carb. After your are sure that the ignition is all that it needs to be, reference Holley's site for your carbs list number and put your carb to factory specs for PV's, jetting, pump cams, squirters, float level and proper fuel pressure. While you have the carb tore down, clean every thing twice, blow out all passages and reassemble with fresh gaskets. Tune from that point, set the idle mix screws at recommended base line setting, then tune with Vac gauge for higest reading at idle. Take it to the track and jet up or down for best mph. Or you can poke at it with a screw driver and hope it goes away :D