427 High Performance Engine Vintage Stats

[Aggressor]

Something offered for an midwinter discussion straight from the
Cobra 427 Chassis Manual.

427 High Performance Engine Specifications

Intake valve opens 0.006 @ 48 Degrees BTDC
Intake valve closes 0.008 @ 96 Degrees ABDC
Duration 324 Degrees

Exhaust valve opens 0.006 @ 96 Degrees BBDC
Exhaust valve closes 0.008 @ 48 Degrees ATDC
Duration 324 Degrees

Valve opening(Overlap) 96 Degrees

Ford Distributor
Maxium Centrifugal Advance Degree Limit = 16
Maxium Vacuum Advance Degree Limit = 8 1/2
Initial timing = 8 Degrees BTDC

A deep breathing cam with generous overlap, 8 Degrees Initial plus 16 Centrifugal Timing with 8 1/2 additional Degrees vacuum on tap (57 crank degrees seems to be rather stiff timing even for 60's leaded fuels)?

-Any Thoughts - I have interest because even with the Paxtons my FE seems to love timing. I am no longer locked down at 10 degrees centrifugal and 12 degrees initial timing for 32 degrees total. I am advancing slowly upwards with spectacular gains. Currently it seems to have maxed-out at 13 Centrifugal, 10 Initial, 14 Vacuum. (50 crank degrees max with vac) 92-93 pump Octane

-Geary

[Naumoff]

Geary,

I may be mistaken but I thought all the HP 427 came with a dual point distributor. What are the specs on them?

A friend of mine had dropped his distributor back in his 427 top oiler and it was running fine and strong but he was having trouble reading his timing. So he brought it by the house and I checked it. He was running 42 initial and I didn't even want to check the advanced. Iron heads and 12.1 compression ratio and a Mallary Uni-light distributor. He runs about a 50/50 fuel mix of Cam 2 and 93 octane. Never heard a valve knock. Swore it ran fine in fact better than ever. I set it to what it is suppose to be and it ran fine there too. It just had the nice rough idle it is suppose to have.
The Misteries of life continue.

P.S. I am not a cam guru.:)

[davebetts]

Very interesting, but I haven't a clue about this much engine depth.
Do most ,you guys, get this stuff. I'll keep reading and learning.

[Aggressor]

Dave it happens by proximity - the fact that you're closely involved in the build you see, hear, absorb, and learn. I didn't care for Holley Carbs but now I'm custom modifying a pair them out of necessity.

Tony -run the numbers above and the intake valve is open 96 degrees into the compression stroke before closing. At full advance ignition occurs a scant 27 degrees later at 57 advance. It seems the engine would have to spin at a 6500 RPM minimum to run decent. Forget idle as I imagine it would be radical at best.

The distributor is listed as a C5AZ-12127-EEZ. The timing characteristics would be the same as a single point. Just the dwell would be extended.

[Aggressor]

Posted by mistake

[Naumoff]

Geary,
The first lab lesson that we had in Electronics Occupation class in High School, un-be-known to us, that just because your instruments say that it should be and the theory says it should be, it ain't always going to be the way you think it should be.

[eliminator]

"He was running 42 initial and I didn't even want to check the advanced. "

I think you better check the actual TDC and the Timing Tape, I bet they don't match.:o

[Naumoff]

"He was running 42 initial and I didn't even want to check the advanced. "

I think you better check the actual TDC and the Timing Tape, I bet they don't match.:o

That was checked and it was good. We checked it when he sheared the gear roll pin on a cruise.
He had pulled the distributor one day on his own to check the roll pin and when he put it back in he was having trouble figuring out his fancy timing light.:)