427 Medium Riser 2x4...

[cjshaker]

This is my basically stock 427 Medium Riser engine that is currently in my '69 R-code Mach 1.

Making 496hp, it probably could have hit the 500hp mark with a bit more tuning and turning it a bit faster, but the HP was leveling off quick and there just wasn't any need to push it that hard and risk the engine. Factory 427 stuff is just getting to expensive.





Block:
Stock 1965 427 Sideoiler block, 4.25 bore, 2 sleeves but otherwise unhurt and not modified other than good machine work.

Heads:
Factory C5-F Medium Riser, 2.25 intake/1.75 exhaust, no porting but small gasket match

Crank:
Stock C$ 427 3.78 stroke, steel crossdrilled crank turned to 10/10

Rods:
Eagle 6.49

Pistons:
Diamond, Forged dome, Compression 10.5:1, Total Seal rings

Cam:
Comp Cams solid flat tappet. 260/264 duration @.050, .581 lift, 108 LSA

Valvetrain:
Comp Cams lifters/pushrods, Harland Sharp rocker system, Oregon Cams shaft support system

Intake:
Factory C5 2x4 Medium Rise, unmodified

Carburetors:
Factory BJ/BK 600cfm Holley vacuum secondary

Oil System:
Factory 7 quart deep sump pan with factory pick-up, Melling HV/HP pump, Arp drive shaft

Ignition:
MSD Pro Billet distributor, MSD 6AL ignition, MSD Blaster 2 Coil

Timing was best at 42*. The larger intake valves likely hurt flow rather than help on unported heads. Except for the cam and valvetrain, basically a stock type 427 using Ford parts.

[plovett]

That's a neat build!  It shows what a factory 427 FE was capable of with some easy modifications.  Really serious stuff, in my opinion.  Headers used were not listed?

paulie

[cjshaker]

Sorry, Paul, I'm actually not sure what headers were used on the dyno. I believe they are just a cheapy set of truck type headers used to clear most of the dyno stuff. In the car I have the standard Hooker headers.

And that was my goal, to keep it basically stock but push the limits. I couldn't do anything about the valve size, the intake valves were already enlarged when I bought the heads. But beyond the slight overbore, cam and pistons, it is basically just a stock 427 design.

[plovett]

So probably 1-3/4" primary headers?

I don't know if or how much the larger intake valves would hurt.  Low lift flow is probably improved a bit?  Which helps flow in the overlap period which in turn might help high rpm power a tad?  I know a certain ratio of port throat size to valve diameter is desirable.  It's maybe around 93%???  If you're under that do you think it's a hindrance? 

paulie

[cjshaker]

Yes, I believe they were 1 3/4" headers.

I can't honestly say about the heads. I wanted to keep them unported and untouched except for a light intake match. The valve size I couldn't help because they were that way when I got them, but they were really nice and a decent price 20 years ago. I'm always surprised by how ports and valve sizes play at different lifts. The cam has a mild lift for it's duration to keep it somewhat easy on the valvetrain, so it could actually help flow at the lower lifts. Joe D. would probably be better at guessing what the results would be of having tunnel-port size valves in the MR head.