1967 427/435 runnig poorly, fuel problem?

[Jerry N.]

I have a 427/435 and it will barely run. I replaced the spark plugs and they were totally black after about 100 miles, and it looks like carbon. Most of them were dry, and both exhausts are puffing black smoke. I checked the timing, put 100 octane low lead aviation gas in, pulled the valve covers off and checked the valves, and tried to adjust the small mixture screw on the drivers side on the center carb, but no help. I used a vacuum gauge for the carburetor adjustment, but it runs so rough you can't get a good adjustment, and the car does not smooth out. If I put a new set of plugs in, it will run slightly better but still puffs black smoke out both exhausts and will foul the plugs in a matter of minutes. The choke opens correctly and the car still puffs and runs rough. Both exhausts appear to be equally black. Also when you shut the engine off, the center carb has white smoke that comes back out for about 1 minute. The exhaust has also done that. I believe the problem got gradually worse, but I kept changing plugs. Any help would be appreciated. Jerry Nutt 31931

[Clem Z.]

Re: 1967 427/435 runnig poorly, fuel problem?

sounds like your carbs need worked on if your timing is correct. could be a blown power valve in the center carb or a warped metering body

[Tracy C.]

Re: 1967 427/435 runnig poorly, fuel problem?

Jerry,

As Clem indicated, you have a fuel problem. Your mixture is way too rich and I would even hazard a guess that to say the white "smoke" that rises out of the center carb after shut down is vaporized gasoline rather than smoke.

I wouldn't run it anymore until you get the carbs overhauled. This is something that will only get worse.

Good luck,
tc

[Jim T.]

Re: 1967 427/435 runnig poorly, fuel problem?

My first guess would be the infamous blown power valve. Quick check is to start the engine and put a finger over the vertical fuel bowl vent, if the engine dies in a few seconds the power valve is not staying closed with vacuum and requires replacement. A simple little ole backfire of the engine can damage the power valve. Something you never want to leave home without is a spare power valve and new metering block and fuel bowl gaskets with a Holley.

[jack farmer]

Re: 1967 427/435 runnig poorly, fuel problem?

I agree with the other responses, I had the exact same symptoms on my '68 tri-power and a new power valve and re-timing fixed it. The smell of gas was thick in the garage after running the car, and the white smoke on mine was gas coming back out of the center carb.