I have a pretty fresh Buick 350 (approx. 300 miles) with a mild ISKY Supercam and 600cfm Edelbrock performer carb. Off the line it stumbles really bad and if I step on the accelerator it sometimes pops/backfires through the carb. Once I'm rolling it performs very well but at really low speed or from a dead stop it is really bad. I went through and checked the obvious stuff like timing and air mixture they seem right from what I can tell but I'm not an expert. Any tip's or advice are greatly appreciated :beer
It could be a number of things but the 1st thing I would do is drop kick that Edelbrock right on to Craigslist. Not saying part of your issues arent ignition but that is a pile of "marketing" junk at its finest.
back fire up thru the carb is typically a super lean condition if its carb related. could be timing related
After verifying timing, one of the things I did to tune that out of my Demon was with larger squirters (along with playing with jets, acc pump cams). To me, it sounds like you have a lot of work to do...
x3 on getting a new carb...had the same issues with an edelbrock on my first Buick 350. Carb cured it.
Buick put a 750 cfm Quadrajet on the 350. Conventional wisdom says 600 should be fine for a 350, but Buicks like bigger carbs. The key to getting a modified engine running right is tuning. The thread on power timing is excellent. Get a carb you can work on and learn how to read the plugs and tune it. As a general rule of thumb a backfire through the carb is a sign of being too lean, a backfire through the exhaust is too rich. Let's guess it's too lean. Since the engine sounds like it works well once you're rolling I would guess the accelerator pump shot is insufficient. If you want to stick with your current carb see what options you have for increasing it. John
My Edelbrock has 3 holes on the accelerator pump arm to adjust the shot. Try setting it on the hole that gives the most travel. Don't lose the micro sized clip!
Well I adjusted the pump arm and turned the air mixture screws in half a turn (clockwise) and it made a big difference. Much better off the line and no more popping through the carb. Man I'm gonna need new tires before long. This is too much fun :eek2:
I know what you guy's are saying about the carb but it was a freebee brand new in the box and better than the stock 2bbl. I am looking into a good offroad carb but not sure what to get? The only one I know of is the Edelbrock truck avenger. Anybody have any ideas?
I just know I'll be taken to task:laugh:.....but I've never been a fan of the Quadrajet. I have a Holley 770cfm Street Avenger on my mildly built SBB 350. Worked perfect right out of the out of the box.....I havnt touched a thing. At least with a Holley you dont have to be a carb "guru" to get it tuned...unlike the QJ. And, if you need any tuning parts...there available "off the shelf", so to speak...unlike the QJ. Extra bonus....Holleys look cool under the hood:TU: Only good thing w/QJ is a little bit better off idle throttle response due to the small primaries. Or if your want the stock look.... Have fun smoken 'em...:3gears:
I just know I'll be taken to task:laugh:.....but I've never been a fan of the Quadrajet. I have a Holley 770cfm Street Avenger on my mildly built SBB 350. Worked perfect right out of the out of the box.....I havnt touched a thing. At least with a Holley you dont have to be a carb "guru" to get it tuned...unlike the QJ. And, if you need any tuning parts...there available "off the shelf", so to speak...unlike the QJ. Extra bonus....Holleys look cool under the hood:TU: Only good thing w/QJ is a little bit better off idle throttle response due to the small primaries. Or if your want the stock look.... Have fun smoken 'em...:3gears:
I'm running an edelbrock carb right now, and I'm having a similar problem. I believe it has to do with the secondaries, and from what I've been told, it is not something you can tune or tweak out of the carb. They run right on some cars, but not on my buick. Going to a BBB qjet!
q-jet makes an outstanding off-roading carb as the float bowl is in the centre of the carb, but they are a chore to tune.
I am thinking of going with the Edelbrock Truck Avenger. It is supposed to be a pretty good carb with good offroading abilities?
Well I have to admit Edelbrock does make decent intake manifolds. That about sums it up. Goodyear makes tires, MSD makes ignition parts, Jesel makes valve train parts, Holley makes carbs... 4150 for me thanks. Easy to tune hard to beat.
Put a holley on it and be done with it. Easy to tune and if you ever change your combo its easy to adjust the holley with it.
