I have a 69 427 / 435hp car I'm getting the engine ready for. This car came without the engine so I have been picking up parts here and there (numbers are not a big deal to me). Weekend driver / No Drag Strip. Car has M21 4-Speed / 3:73 Gears. I have the following engine parts:

4-Bolt Main Gen IV Block, .030 over
Steel Crank, Std rod and mains
GM Dot Rods, 7/16 rod bolts
Rect. Port 110cc Heads (Org 69 Heads)
All stock covers
Stock Exhaust Manifolds (will use under car exhaust w/ Flowmaster 40's)
Orginal 427 Tri-Power setup

What Pistons and valve train should I use to get me in the 435-450 HP Range?

Option 1

Build to orginal GM specs: 11:1 Comp / Crane Blueprinted Solid Lift Cam

Option 2

Looking for advice from you engine experts. I know Old school was high comp = HP, new school is low comp w/ right cam = just as much HP. If I opt out for Non orginal GM specs (which is ok) I'm thinking I want to go with a Hyd Cam. I also want to retain the Org. GM Valve covers.

Thanks in advance of any ideas.


[Modified by Mr D., 7:22 AM 12/9/2003]


[Modified by Mr D., 7:52 AM 12/9/2003]

 

I would think that a conversion to a roller-cam would be a worthwhile change to the valvetrain. It frees up some HP, and allows you to run a little more radical ramps on the cam to snap the valves open/closed faster.

Might want to consider roller-rockers on it as well. They might not fit under the stock covers, but Chevy makes a really nice set of cast aluminum covers with either Bowties or Chevy on them. They look sweet on the big-blocks I've seen.

If you are concerned about the stock look on the outside, at least get a roller cam in it. Flat tappets are always a bit dicey on break-in. You can get a roller in any config you want, including some of the "hot" cams available from GM for the BB cars...like some of those "secret" Duntov cams they produced in the 60's & early 70's.

Good luck with it. Only thing I'd change is the block....

To a ZL1 aluminum one :D

All the cubes of a BB but the weight of a SB. Of course...they cost about $4500 from GM for the bare block. :eek:

 

There's no "old school" or "new school" on compression ratio and valve timing - just a simple rule of thumb - the later the inlet valve closes, the lower the dynamic compression ratio and the more static compression you can run on a given fuel octane rating.

Also, all other things being equal, a later closing inlet valve shifts the torque curve up the rev scale, so the engine makes more peak power at high revs, but less at low revs.

When running manifolds you have to be reasonable on overlap. The OE SHP mechanical lifter cam is probably as good as it gets without subjecting the valvetrain to excess inertia forces, which will require stiffer springs and reduce reliability and durabililty.

When building an engine from components always go with the largest displacement possible at reasonable cost. This would mean building a vintage BB with a 4" stroke, which yields 454 CID with the standard 4.25" bore. All other things being equal - bore, cam, heads, CR, inlet and exhaust system, a longer stroke engine will make about the same peak power, albeit at lower revs (by the inverse of the ratio of strokes), but will have better torque bandwidth make more average power across the operating range.

Duke





[Modified by SWCDuke, 5:57 PM 12/10/2003]

 

Dennis, 435 - 450 hp is not all that hard. That goal would be ever so much easier to hit if you ran headers. Big blocks love headers, even big blocks that are not romping stomping dragster engines. To run on pump gas you'll want to keep compression under 10:1 for sure. I too think you might as well go bigger while you are in there - no one can tell by looking what displacement you have.

I need to find the dyno sheets to get the exact numbers, but my 468 SC engine made ~ 480 hp without the centrifugal supercharger attatched - all this with only 8.3:1 compression and a mild hydraulic stick .547/.547 lift 232/237 duration 112 LSA installed at 110. My heads flow more than yours, but at that power level it wouldn't make a great difference.

Thomas