1973 Custom Classic 454 (Loss of Power)

[notyo_cheez]

Originally Posted by savatreatabvr

This may be a stupid question but can not having a choke at all affect it's performance once it's warmed up?

No choke when it's warmed up shouldn't matter. If the choke doesn't work you might want to do something to get it working again, on a 4bbl the second stage should open when you push the pedal naturally. Choke thermostats are common failure points on the old Rochesters.

If your budget allows for it look at an aftermarket Edelbrock or Holley and get rid of that Quadrajet. They worked well when new but when they wear out they're more trouble than they are worth. All the GMs I ever owned with Roch carbs always had problems.

But before you take out a second mortgage on the house to fund your repairs check all your vacuum lines, get a manual for your truck and look for the specs for choke/carb adjustments and if you feel plucky get a rebuild kit and tear it down. Most of the time cracked vacuum lines will wreak havoc with engine behavior so insure you are all tight where you need to be before you start turning screws.

[cjlinkster]

Is your engine running at the correct operating temp? I suggest that you may want to check your thermostat.

On my 454, the prior owner took out the thermostat, and the engine wasn't warming up past 160 degrees.

Mine's a 1984, its vacuum advance source is from a line connected to a temperature switch on the front of the engine. Without having the engine operating in the correct range (190 to 210), it's timing seemed to be off (low power, etc..). I suspect that the vacuum advance wasn't working correctly or even at all.

With the new thermostat, it is running a lot cleaner and seems to have more power.

[motornut]

speaking of vacume advance check the dizzy weights move freely

[savatreatabvr]

Another good tip, I'll check it out in the morning!

Originally Posted by motornut

speaking of vacume advance check the dizzy weights move freely

[savatreatabvr]

I've learned to not overlook the simple things that I think are insignificant to the issue I'm have with this 454! I mentioned before that it had no power and ran rough well after replacing the plugs, wires and Quadrajet kit it ran better but it ran great after I simply moved the Accelerator Pump linkage from the lowest hole to the top hole of the arm the actually pushes the plunger down into the carb. I may be getting ahead of myself because I haven't started it yet today but I've got high hopes so thank you all for the excellent troubleshooting ideas.

[savatreatabvr]

You know what, you're right!!! You jumbled my memory, back in Okla I had a 72' Chevelle with a 454 when I was 17 years old, 25 years ago, and it had a huge radiator just like my truck does now but the Chevelle wasn't getting up to operating temp so I'd put a piece of cardboard in front of the radiator to get it to run hotter and it solved my problems. I'll try the same thing on my truck and see what happens! Thanks cjlinkster!

Originally Posted by cjlinkster

Is your engine running at the correct operating temp? I suggest that you may want to check your thermostat.

On my 454, the prior owner took out the thermostat, and the engine wasn't warming up past 160 degrees.

Mine's a 1984, its vacuum advance source is from a line connected to a temperature switch on the front of the engine. Without having the engine operating in the correct range (190 to 210), it's timing seemed to be off (low power, etc..). I suspect that the vacuum advance wasn't working correctly or even at all.

With the new thermostat, it is running a lot cleaner and seems to have more power.