The New Project: Part Deux!

[njsteve]

And the real surprise: domed TRW L2394N pistons. That explains the 230 psi compression test results and the detonation on anything less than racing fuel. So what do we have 10.5 to 1 ratio with the 111cc 7F6 heads?










In googling the part number I found this:

"L2394NF .030 TRW pistons for Pontiac 455, )
.476 dome aluminum forged for high compression.

Unmachined Compression Ratios:
89cc = 12.54:1
96cc = 11.83:1
111cc = 10.25:1
114cc = 9.98:1

These pistons are generally used for racing applications, and may require
machining for proper fit and clearance of smaller chamber heads."

[njsteve]

And the camshaft looks to be a Crane #283941



And here is the info on that camshaft:

Crane Cams 283941 H-272-2 Hydraulic Flat Tappet Camshaft Pontiac 265-455 V8 55-81 Good low and mid range torque, Good idle, daily usage, towing, performance and fuel efficiency, 2600 - 3000 cruise RPM, 8.75 to 10.5 compression ratio advised.
Part Number: 283941
Grind Number: H-272-2
RPM Power Range: 1800-5400
Duration Intake @.050": 216
Duration Exhaust @.050": 228
Advertised Duration Intake : 272
Advertised Duration Exhaust: 284
Lobe Separation: 112
Valve Lash Intake: 0
Valve Lash Exhaust: 0
Gross Valve Lift Intake: 0.454
Gross Valve Lift Exhaust: 0.48

[njsteve]

Looks like some aftermarket forged, pressed pin, connecting rods. Do these look familiar to anyone?

[njsteve]

The crank is std on both the rods and the mains.





The wear on the rod bearings looks like detonation was taking its toll.

[njsteve]

Some interesting clearancing on the piston skirts:

[njsteve]

And the cause of the oil leak. The rear main had spun and compacted itself so there was a one inch gap in the rope seal, in the cap area.





I used Plastigage and checked the oil clearances on the rods and mains and they were .002. I also checked end play and side clearances and they were in spec as well.

[njsteve]

After comparing with some stock rods I had in the garage, it turns out those are stock cast rods with the side beams polished.

Here's the underside of the heads:



The crank:



The soon to be replaced rods and pistons:



and the empty block: