Need help tuning a 454
Need help tuning a 454 Just bought a 72 Camaro with a 454. Don't know much about the engine, except that it is a crate motor. It had an old Quadrajet intake and carb on it when I bought it. For some reason, the intake ports were slightly too small and blocked the secondaries on the carb from opening. I picked up an Edelbrock RPM Air Gap intake and Performer 750 carb. I installed both and did not do anything to the carb out of the box. The timing tab on the timing cover was all ripped up, so no notches were visible, but "before" and "aft" were visible. Using these two indicators as a guide, I timed the motor to what I believe is 10 degrees. The car idles fine, but when I took it for a drive and hit the gas to open it up just a little, it stuttered so bad that it through my head back and forth. The car accelerates, then feels like it gets completely starved for a split second, then accelerates again, then stops again, all through the RPM range. I don't know much about getting these motors dialed in after swapping parts, so I need some help. Don't know if it's a carb issue, timing issue, vacuum issue, or all of the above. Need some lessons on troubleshooting. Any help appreciated.
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Joined: Jun 2009
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From: Tulsa, OK
A carbed BBC tunes no differently than any other carbed engine. Air, spark, fuel. You've got either a fuel delivery problem, or an ignition problem, but more detail is needed to help much.
Does it start and idle properly? What's the idle rpm, and did you have any trouble getting idle speed adjusted? If you go full stroke on the carb (engine off), do you see 2 solid streams of fuel squirting in the carb primaries? Is the vacuum advance hooked up in the right spot?
More info, please.
P.S. Just my opinion, but you'd have been much better off leaving the Q-Jet on the car. Superb carb when they're dialed in. The Eddy, not so much.
Does it start and idle properly? What's the idle rpm, and did you have any trouble getting idle speed adjusted? If you go full stroke on the carb (engine off), do you see 2 solid streams of fuel squirting in the carb primaries? Is the vacuum advance hooked up in the right spot?
More info, please.
P.S. Just my opinion, but you'd have been much better off leaving the Q-Jet on the car. Superb carb when they're dialed in. The Eddy, not so much.
The car idles fine after warming up. The carb has a manual choke, so I do have to feed it until warm or it dies out. Immediately after the parts change and timing, it idled at about 500rpm (choppy). I adjusted the carb idle screw and brought it up to about 850, though I noticed after I came back from the drive, the idle seemed to dip again. The vacuum advance canister is hooked up to the driver's side vacuum port of the carb, which is the "non-egr" side. I watched an Edelbrock troubleshooting video that said about 90% of vehicles should be hooked up to the passenger side port, but my speed shop guy told me that I had it in the right spot. I will be doing anything that is suggested here this afternoon, so I'll check for those two streams at full open and report back. I also plan on making sure that my plug wires are in the right order on the distributor and switching the advance vacuum ports to see what happens. I did have a problem re-installing the distributor and had to practically crawl into the engine bay to turn the oil pump drive slot with a screw driver in order to get the distributor to fall in. It seems to me that the distributor sits a little crooked. I'll try to post a picture of the engine bay, in case that will help. Thanks.
Carb seems to be working properly and has two fuel streams going to primaries at full open. Advance hose is hooked to the right port (driver's side). I tried hooking it to the passenger side vacuum port, but then the car wouldn't even idle. I went to pull the #1 plug and the wire boot was stuck on it. The boot pulled off, leaving the metal contact on the plug. I'm going to have to get a new set of wires before continuing. The #1 plug was black when I pulled it.
