Back nearly 20 years ago, I bought a #1406 Edelbrock Performer Carburetor for my 65 300 horse Coupe. The car only got 200 miles of driving after finishing the body-off and about 50 to 100 miles after the new carb installation. Took it out of mothballs recently and remembered that then as now, the engine had a slight surge while under cruise conditions. Back then I verified the float level was as it should be right out of the box and then proceeded to try various rods and jets but that light surge was still present. Recently, I've been taking care of a few things to get it ready to drive again and went back to the owners manual that came with the carb and again verified the float level is still the same measurement - 11/32.

Last night I was looking through an old Chevy High Performance Magazine, dated 2005 and I saw in one of the Q&A sections their recommendation to set the Performer Carb to the prescribed settings which was '7/16', not 11/32 which is 3/32 higher than what is now recommended. Haven't changed the float to that new 7/16 measurement and it might not change my surge condition but 3/32s higher might have been enough to cause that surge after all. I've checked their website but the only reference to float level in the 1400 series Performer carbs is for that 7/16s dimension. I'll report back after I get the carb readjusted and give it a test drive but does anyone know if the Performer Carb's are different now from back then or if not, when did they change the float level dimension?
Mike T.

 

It might be running lean. Maybe increase jet size a little.

 

I asked a somewhat similar question over 2yrs ago. It received zero replies (which I attributed to my Avatar pizzing people off). I noticed a difference between the specs listed in the owner's manual and those listed in the rebuild kit.

I tried both specs and liked the owners manual best. Anyway, here's a link to my old thread.............

http://forums.corvetteforum.com/c3-t...ed-advice.html

 

7Vettes - Was it the same Avatar you have now? If so, I guess they didn't have a sense of humor. The owners manual(s) I got with the carbs (we had two 65 300 horse Coupes at the time) were both dated 1989. Can't remember exactly when we bought the carbs but figure it had to be very early in the 90's. The 300 horse 327 in my 65 saw a lot more time up on jackstands than it did rolling on down the road so it's not like I had plenty of driving experience with it to determine the new carb was causing the slight surge or not. From my (all too brief) notes I wrote in the owners manual, I tried a number of different rod/jet combinations but never did nail down the cause of that surge. The plugs did have a dry black/sooty look to them but figured that could have been due to a possibly slightly-tired engine. It had been 'rebuilt' before I bought it in '85 and the compression readings were just okay so the surge issue was chalked up to a less than great ring seal and valve stem seal. Now that there's a chance the float level settings were higher than they should have been, maybe a simple float 're-adjustment' might make things right again.
You said you preferred the 7/16 measurement in your owners manual over the rebuild instructions, were you having overly rich conditions at the higher setting?
Mike T.

 

we just had an entire thread devoted to this called 340 stumble.....most likely your idle air screws are in too far...if you set them with a vacuum gauge at the highest point, that's waay too lean for an afb... back them out 1/2-3/4 turns more and try it......good luck

 

Pretty much.

 

Nope, I always set the idle screws with a vacuum gauge hooked up, and while in the process of finding that 'perfect' setting, I always run it in and out at least a half turn past the setting that gives me the best vacuum reading and also let it run at those points to see if there's any adjustment to it.

It will be interesting to see how it runs after I try this lower 7/16-inch float setting.
Mike T.