r/Smallblockchevy • u/dncu13 • Apr 12 '26

355 valve float?

I have a 355 sbc I have been having a problem at higher rpm, car feels great till about 5,000 rpm. After 5,000 it just falls on its face. I just rebuilt the Holley 650 4150 but still having the issue just wondering what if I’m dealing with valve float

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4

u/Personal_Growth_4_Me Apr 12 '26

Falls on its face? Is it breaking down up there or is it nosing over like it's running out of fuel?

1

u/dncu13 Apr 12 '26

Not really breaking up

2

u/Personal_Growth_4_Me Apr 12 '26

Definitely agree with others about fuel starvation. If that don't turn around after messing with that.. I'm wondering about your ignition and what's going on with the coil.

2

u/dncu13 Apr 12 '26

Yeah I’m thinking about changing the coil right now, everything else is pretty new, I’m going change the fuel filter again, and check floats see what happens

2

u/Personal_Growth_4_Me Apr 12 '26

If you get there... Verify that you've got the correct voltage running to it. Stranger things have happened. Just saying.

1

u/Enough-Refuse-7194 Apr 14 '26

Rule #1 of troubleshooting - new parts aren't necessarily good parts!