Sputtering under heavy load

[zachste]

Truck details: SBC 350/th350, edelbrock carb, big solid roller cam.
Drove it Friday night, it was fine. Drove it 100 miles saturday, it was fine. Saturday evening I pulled the valve cover to change the gaskets to thick rubber gaskets only to realize I need long bolts to run them, so put the older rubber gaskets back on. Then I changed my oil yesterday (Valvoline 10w30 and Lucas oil treatment). Took it out last night for a drive, and under WOT it's sputtering from about 3k-4k rpm. Driving it under normal conditions (even and slow on throttle), it runs fine all the way to 5k. Sputters once it gets up in RPM from a stop as well. I spilled some oil when filling it back up, so was thinking maybe the #8 plug/wire got wet. Pulled the wire and the plug and seemed fine. Put it back on and drove it to work this AM, and it's doing the same thing. Coincidence that this didn't start until the oil was changed? Runs great until the pedal is mashed, idles great, etc. So after searching I see this could be a number of different problems.

Edit: Seems to be a common problem with the 1406 edelbrock carbs. Am I off base here? I'm thinking either ignition issue, or fuel delivery issue?

[ElKotze]

Almost sounds like it doesn't get enough fuel for some reason. Partially plugged fuel filter?

[rally]

Is it a sputter or is it bogging? I had some issues with my 1406 until I adjusted the accelerator pump. Before then, if I accelerated really slowly, it wouldn't bog too much, but if I stepped on it, it would bog down really badly. WOT would cause it to fall flat on its face.

I'm assuming your fully warmed up when you notice the sputtering. If not you'll sputter and bog, too.

I'd do what ElKotze suggested and check the fuel filter. Sounds like you might be starving the carb.

If all that looks good, I might check the carb floats to see if one is full of gas. My truck sputtered and eventually quit running altogether because the carb flooded.

[hamjet]

if it ran fine before you pulled the valve covers, it may be a plug wire not plugged all the way on the cap or plug,( if you removed them to pull covers) or maybe the plug wire it's self. also check to see if all vac. hoses are on that may have been disturbed while under hood...

[zachste]

Originally Posted by ElKotze

Almost sounds like it doesn't get enough fuel for some reason. Partially plugged fuel filter?

Yea that's what I'm thinking/hoping.

Originally Posted by rally

Is it a sputter or is it bogging? I had some issues with my 1406 until I adjusted the accelerator pump. Before then, if I accelerated really slowly, it wouldn't bog too much, but if I stepped on it, it would bog down really badly. WOT would cause it to fall flat on its face.

I'm assuming your fully warmed up when you notice the sputtering. If not you'll sputter and bog, too.

I'd do what ElKotze suggested and check the fuel filter. Sounds like you might be starving the carb.

If all that looks good, I might check the carb floats to see if one is full of gas. My truck sputtered and eventually quit running altogether because the carb flooded.

It sputters and pops through the exhaust and acts like it wants to fall on it's face.

Originally Posted by hamjet

if it ran fine before you pulled the valve covers, it may be a plug wire not plugged all the way on the cap or plug,( if you removed them to pull covers) or maybe the plug wire it's self. also check to see if all vac. hoses are on that may have been disturbed while under hood...

I didn't pull plug wires to pull the valve cover. I only pulled the passenger side valve cover. I did double check them though, as well as for anything I may have knocked off/loose and saw nothing.

[bill3rail]

Sounds like lack of fuel to me. Filter or carb adjustment.

Bill

[zachste]

Just wanted to give an update for future/search references. I checked some normal stuff like fuel filter, debris in a bowl of carb, vacuum leaks, plug wires, plugs, etc all were good. I needed some assistance so took it out to my buddy's shop and first thing he wanted to check was timing. Said no way that could be it. Initial timing was too advanced, brought it back a little lean to I think it was 28*-30* advanced total timing, and ran great after that.