[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.

[muscle_collector]

crane used to make a cam they called the blazer. seemed like it had around a 443 lift. it was a really good cam for this type of engine. i used it several times on 74-79 400 engines and it has a real nice lope to it and would make a 13 second car with 3:08 or lower gears. no idea if it is still made.

[Dauntless1971]

Originally Posted by Baba O'Riley

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

To the best of my knowledge the SPC-5 is a copy of the late 50's early 60's 389 with 3 2 barrels 524886 camshaft. The number that stands out to me is the 66.5 degrees of overlap, which is more than the 068 camshaft. But the same .050 duration as a 067 cam.

I would think you would need a 10 to 1 .compression to run that cam. I have some specs on a few Pontiac cams I attached. The numbers vary a bit from other sources.

I read somewhere once Melling had a SPC-6 that was an 067 copy but I guess it did not sell well enough.

[unruhjonny]

@ Baba;
I made a spreadsheet on Pontiac cams BECAUSE I had hoped to find either a replacement 067, or the best substitute which might keep my car eligible for the Pure Stock Musclecar Drags;

The 067 is NOT availble.

Most vendors who say they have one are selling a replacement for the 066 cam;
That summit grind used to be known as the 067HL (HL stood for High Lift).

if we take a snapshot of the 1968-1972 model years, the 066 and 067 could be described as follows:
067: 4bbl cam
066: 2bbl cam
Neither of these cams were used for the higher powered engines;
The 067 was used for the base GTO’s, and the 066 was a small step down from the 067.

It reads as though you might be on the cusp of driving yourself bonkers trying to figure this all out;
Short of spending money on an NOS 067 cam (there are a few out there) you’re either going to go for a slightly larger cam, or downgrade it.
I would suggest either getting the 068 replacement, or the summit grind.

The logic behind the “067HL” was that many people were using 1.65:1 rockers in place of the stock 1.5:1 rockers on the 067 grind, and this grind was essentially supposed to replicate the 067 with the 1.65 rockers.

Please don’t drive yourself crazy trying to find a cam grind that cannot be bought new.

[b-man]

Put the Summit 2800 in it and be done with it. It’s perfect for what you’re doing and will run strong.

https://forums.maxperformanceinc.com...1&postcount=22

I had one in a very similar 400 with 8.2:1 compression which is exactly what your ‘71 400 had from the factory. The only 1971 engine with a higher compression ratio was the 8.4:1 455 HO that used the 068 cam.

[Baba O'Riley]

Okay, yeah, guilty of overthinking this. I've been having one thing after another with the motor (slipping rockers etc.) and I want to stop chasing problems here. I'll probably go with that 2800 and some good-quality lifters. Thanks again to everyone for their time and knowledge.

[67Lemons]

You couldn’t give me a box of anyone’s white box lifters, either pay the money for HLJ’s from Butler or some Rhodes or Crower cam savers or order some Eaton’s from Spotts, you don’t want to lose a lifter and have to start all over, if you’re going to over analyze anything it should be the lifters IMO.

https://butlerperformance.com/i-3164...html?q=Lifters

https://www.ebay.com/itm/27693325325...EAAOSwZEJds48H

https://rhoadslifters.com/product/9518xl/

https://www.summitracing.com/parts/c...6/make/pontiac

[Jay S]

All the stock type cams, 066, 067, including the 2800 all use stock valve springs. The machinist should be able to proceed and assemble the heads with stock valve springs.

[BLUE TA]

I put a 068 in a 74 455 TA 308 gears th400. ran 13.91 @ 98.47 at sacramento before it closed.

[PAUL K]

The specs on the Crane Blazer mentioned above

288/300 adv.

218/230 @ .050

114 LSA

.450/.465 with 1.5

The factory cams work well but were short on lift. They have long lazy lobes which seem to compliment the flow characteristics of a stock Pontiac head. It's easy to improve on them by adding hi-lift rocker arms. Or with a well spec'd aftermarket camshaft, especially if the engine is compression challenged.

[Squidward]

I never ran the 2800 in a 400, but suspected it would be a great cruiser street cam. I really enjoyed it in a 350, and cracked into the high 14's with it. No extreme valvetrain stuff needed, made many passes with press in studs.

Would be my cam of choice for 350 or 400 builds in the future as I've become more chill, and value overall reliability and simplicity more these days.

[Baba O'Riley]

Going with the Summit 2800 and Crower lifters. Thanks again, everyone.

One last thing -- what's the zinc additive you like?

[SD455DJ]

Originally Posted by Baba O'Riley

Going with the Summit 2800 and Crower lifters. Thanks again, everyone.

One last thing -- what's the zinc additive you like?

Good choices. We just use Brad Penn, Valvoline VR1, or other high-performance oils with the ZDDP in it already and never have had any issues. For break-in, use any good moly break-in paste that sticks to the lobes...others will most likely chime in with their preferences.

Dennis

[Jay S]

I usually use a beak in oil versus an additive for break in. Driven BR is what I generally use.

Crower’s lifters are made by Eaton. Most of Summit’s flat tappet lifters are made by Eaton too.

The only USA made HFT lifters are from HLJ. They make the lifter bodies for Howard’s and Rhoad’s. HLJ use to make the lifter bodies for Howard’s, Lunati, Crower, and many others. After their price leap a few years ago Crower has not used HLJ lifters for a few years.