427 engine loss of power

[b dworsky]

During the last Bloomington tour my 1966 427 convertible was constantly being challanged by a 2006 ZO6 on every stop. During these events I noticed that every time my RPMs went over 4500 my engine seemed to bog down and even decrease in power. This seem to happen no matter what gear I was in. What gives? The engine had been rebuilt a number of years ago prior to myself and all the external parts(Intakes,carb,trans,heads, valves) are original.
Thanks

[Rob Dame]

Re: 427 engine loss of power

Sounds like it's starving for fuel. Ckeck fuel pump pressure, fuel filter and the most overlooked item is the filter on the end of the pick-up in the tank. Rob

[Wayne K.]

Which 427, 390 or 425hp ? *NM*

[b dworsky]

Re: Which 427, 390 or 425hp ?

The 427 is a 425 HP.

[Rick S.]

Re: Which 427, 390 or 425hp ?

Which door did he blow off, the right or left one? Or both?

[Mark #28455]

start with the basics

First, check that your fuel delivery is ok, check the fuel filter, check the "sock" in the tank, you may even want to pull off the carb fuel bowls to see if any crud is lurking - gasohol sometimes builds up a nasty white goo.

Second, check your spark plugs and wires (the stock type braided wires break down over time). Check your cap and rotor. Check your timing - are both the vacuum and mechanical advance systems working - you'll need to rev the engine up to total mechanical advance to verify the total timing (without the vacuum it should be about 34 to 36 degrees). Do you have an MSD or other aftermarket ignition? If so, the leads from the Mag Pulse pickup coil are pos and neg and if installed in the wrong position, your timing will be all over the place. Do you have a stock suppression capacitor on the coil? They break down with age and will essentially ground out your coil.

Are your lifters properly lashed? Are your valve springs getting weak and allowing valve float? (incidentally, the problem with valve float at moderate RPM is when the valve bounces off the seat on closing, not that it hits the piston) Is the compression or leakdown test similar on all cylinders? Is your camshaft worn?

The list goes on and on, start with the cheap stuff first. Then again, if it was a 500 HP ZO6, that's just par for the course! That car will pretty much blow away all the vintage cars, even the L88's .

Mark