[Baba O'Riley]

Originally Posted by Dauntless1971

The specs of Melling camshaft you show are actually for the SPC-4. Almost every vender selling them list it wrong. I made a copy from their catalog.

Thanks for that. But &*%#, these guys don't make it easy for us, do they? Crazy.

Melling's Camshaft Specs ID Chart on their site says this for the SPC-5, based on 1.5 rockers:

Duration @ .050 -- 198 int., 208 exh.
Advertised Duration -- 272 int., 280 exh.
Valve Lift -- .404 int., .408 exh.
Cam Lift -- .270 int., .272 exh.
Center Line -- 106 int., 116 exh.

Then they list these exact same specs for the SPC-4, as do sites like Summit. So I found Melling's parts lookup page which had more detail, and here's where's there's differences:

Intake Valve Closes at 0.006 in. Cam Lift (SAE) : SPC-4, 70 ABC; SPC-5, 78 ABC
Intake Valve Opens at 0.006 in. Cam Lift (SAE) : SPC-4, 21 BTC; SPC-5, 26 BTC
Exhaust Valve Closes at 0.050 in. Cam Lift : SPC-4, -12 ATC; SPC-5, -11 ATC
Exhaust Valve Closes at 0.006 in. Cam Lift (SAE) : SPC-4, 32 ATC; SPC-5, 40 ATC
Intake Valve Closes at 0.050 in. Cam Lift : SPC-4, 25 BBC; SPC-5, 26 ATC
Intake Valve Opens at 0.050 in. Cam Lift : SPC-4, -7 BTC; SPC-5, -6 BTC
Exhaust Valve Opens at 0.050 in. Cam Lift : SPC-4, 40 BBC; SPC-5, 41 BBC
Exhaust Valve Opens at 0.006 in. Cam Lift (SAE) : SPC-4, 68 BBC; SPC-5, 73 BBC

To be honest I have very little idea what any of these mean, but this is where they're different.

Finally -- Butler Performance lists the SPC-5 as a comp for the original GM 9779067 cam (what I want), while PartsHawk says the comps for the SPC-5 are GM cams 537441 and 529472.