Joined
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237 Posts
Uh Oh, not liking the sound of this! :unhappy:
The '68 suddenly started running poorly last night, acted like it was running out of gas.
Could not be, the tank is full.
So today I changed out fuel lines, filter, replaced the missing filter in the Quadrajet, and ran some spray cleaner down the venturies.
OK good, runs much better............... except!
I had noticed when I first got it that there was some weakness in the upper RPM range.
No surprise, the car sat a long time, so I put some Lucas fuel system cleaner in at the first gas fill.
After doing what I could to clean up the fuel system today I took it out for a little test drive.
Engine is a 400SB+30/400 trans with shift kit.
So far as I know the engine is basically stock.
Good idle and pulls strong now, BUT!
At higher rpm I hear a sound I dread, light popping at the carb!
It could be I'm floating the valves, no tach so I'm unsure of the RPM.
What is the max RPM for a stock 400 anyway?
Doesn't seem like it's really being spun that high.
Lean carb?
I get gas smell, so a high fuel level and rich seems more likely, and not expected to cause popping.
My cam is going flat isn't it! :banghead:
I did not have this engine built, but the first thing I did when I got the car home was an oil change, "racing oil" WITH ZDDP to protect the cam.
Seems I was already too late, maybe why the car sat?
Hydraulic lifters, but I suppose I should still be able to measure or at least compare the lift if I pull a valve cover?
I looked at cams on-line, then I looked at roller cam$, going to have to be another flat tappet cam due to cost.
Car is a daily driver, I like power but still need decent mileage and do not race.
Will be doing occasional light towing.
I'm thinking Edelbrock Performer cam, put on my Performer manifold at the same time, keep the quadrajet until I can get the Edelbrock FI system.
So, is my thinking sound?
Something simple I missed?
Better cam for a 400 engine daily driver?
400 Red-line?
Serious suggestions?
The '68 suddenly started running poorly last night, acted like it was running out of gas.
Could not be, the tank is full.
So today I changed out fuel lines, filter, replaced the missing filter in the Quadrajet, and ran some spray cleaner down the venturies.
OK good, runs much better............... except!
I had noticed when I first got it that there was some weakness in the upper RPM range.
No surprise, the car sat a long time, so I put some Lucas fuel system cleaner in at the first gas fill.
After doing what I could to clean up the fuel system today I took it out for a little test drive.
Engine is a 400SB+30/400 trans with shift kit.
So far as I know the engine is basically stock.
Good idle and pulls strong now, BUT!
At higher rpm I hear a sound I dread, light popping at the carb!
It could be I'm floating the valves, no tach so I'm unsure of the RPM.
What is the max RPM for a stock 400 anyway?
Doesn't seem like it's really being spun that high.
Lean carb?
I get gas smell, so a high fuel level and rich seems more likely, and not expected to cause popping.
My cam is going flat isn't it! :banghead:
I did not have this engine built, but the first thing I did when I got the car home was an oil change, "racing oil" WITH ZDDP to protect the cam.
Seems I was already too late, maybe why the car sat?
Hydraulic lifters, but I suppose I should still be able to measure or at least compare the lift if I pull a valve cover?
I looked at cams on-line, then I looked at roller cam$, going to have to be another flat tappet cam due to cost.
Car is a daily driver, I like power but still need decent mileage and do not race.
Will be doing occasional light towing.
I'm thinking Edelbrock Performer cam, put on my Performer manifold at the same time, keep the quadrajet until I can get the Edelbrock FI system.
So, is my thinking sound?
Something simple I missed?
Better cam for a 400 engine daily driver?
400 Red-line?
Serious suggestions?