Camshaft recommendation for '71 400, Type 96 heads?
 

The #96 heads on my '71 Formula have to be redone. The rebuilder needs cam specs for that of course -- and the old cam is kind of a UFO, no brand logo or model numbers I can make out so I'm going to just replace it. I want to keep the motor flat-tappet so there's no replacing stock stuff like the valley pan etc.

The new cam, I'd like it close to the stock GM 9779066, or maybe the HO 9779068 for a slight step up from the -66 power-wise -- just nothing too crazy that's going to make it run rough or cause trouble elsewhere. Anyone have recommendations for what I want? I know companies like Howards and Melling sell copies of 9779068 and 9779066 cams.

One other question -- if I do go with an HO-style 9779068, will that work with the stock valve springs on a '71 400? If not, does anyone have a recommend on what springs to use as a replacement? Are there any other valvetrain components that will need to be upgraded?

Thanks --

I believe your stock grind was a 067;
This grind is virtually unobtainable.
If you stick with an OE grind, there’s no messing around or worrying about anything.
As I have understood it a 068 should work fine - that is what the 70-RAIII & 71/72-455HO all used.

I personally would not step down to a 066 grind.

Others here will probably have better first hand knowledge or opinions than me.

If your cam looks good, and you have the time you could try measuring it.

Howards sells a knockoff of what they call a "Near duplicate of the Pontiac Ram Air I/II 375HP/400 cam (GM# 9779067)." LINK

Just my 2 cents, Love the 068 in my 71 400, 4 speed car. I am using a Q jet with a Cliff tune it.

that description is messed;
and I seem unable to use the link.
RAI = 744
RAII = 041

The 067 was the most common used grind for Pontiac, and iirc it was used up to 1976 in most of the (non-RA) 4bbl “performance” (or ‘bread and butter’) engines;
iirc 1967-1972(?) L78 used it, and 1970-1976 L75 used it.

The 068 is a pretty mild cam.

A couple items help in the decision, such as compression ratio and axle. I’ll assume you have 8:1 compression and 3.08 or 3.42 axle. I’d strongly suggest nothing more aggressive than the 068 grind (.410 lift and 288/302 duration which in modern speak is about 225 @ .050). More duration and you will kill bottom end torque with low compression. You could put an 067 or 068 grind together and if you find you can tolerate a little more valve opening you can add 1.65 rockers.

I just want to punctuate one part of Giles' post:

Be sure to not lower compression;
Those multi-relief pistons won't help you, and try to pay attention to piston height to ensure you don't unintentionally lower compression.

If my memory serves me, your engine was rated at 8.3:1 or 8.4:1 - I would do what ever I could to ensure you don't go less than that.

I ran the Wolverine Blue Racer series cams on my drivers for years. I believe Wolverine has gone out of business, but you can still buy the exact same camshaft grind from Summit Racing. This is the cam I'm running in my 1974 455 (Y-code) with automatic, a/c, and 3.08 rear gear. It is an excellent choice for the street.

The equivalent is the Melling M-Select Class 2 Camshafts p/n 26204. The specs are:

Camshaft, Hydraulic Flat Tappet, Duration @ .050 in. 214/224, Lift .443/.465, Pontiac, V8

It has a little bit of lope, but still works well with a 400 or 455 with an automatic transmission and a/c.

The ‘78/’79 W72 400 is very similar to your ’71 400 with 96 heads. This is a ’78 400 (with the good 481988 block) that is 0.040” over with forged pistons & rods. The stock 6X-4 heads were resurfaced minimally to be trued and measured 92.5 cc’s in the chambers. With .040” quench, it calculated out to be 8.75 to 1 static compression ratio. We used a Summit 2800 cam (204/214/112 @ .422”/.444” lift which is very close to the factory original 067 cam specs ) that we had sitting on the shelf with new ‘stock’ style valve springs. It made 360.3 hp @ 5000 rpm (still climbing) and 456.1 lb-ft torque @ 3600 rpm on the dyno. With a little fine tuning (jetting and timing) it maxed out at 371.4 hp @ 5000 rpm and 460.3 lb-ft torque at 3600 rpm. It had D-port RA exhaust manifolds with 2.5” mandrel bent head-pipes for all pulls.

You don’t need to over-cam these engines to make good power.

Dennis

I am incline to believe that this is where most go overboard...

Also, you (Dennis) pay particularly close attention to compression;
That calculated 8.75:1 compression is a bump from stock - those had a factory rating of 8:1 or something like that...

When I posted last night I was trying to recall which was the 067HL cam - thanks for sharing that!

Axle is the GX code 3.08 it was born with. Original heads / intake, AT, and a correct replacement Quad from the mid-70s, so compression should be close to what it was made to run on.

Howards website confirms that the -68 cam needs upgraded springs from stock. I'm going to call them and ask for a recc on what kind to use.

That advertising certainly isn't true. That very closely duplicates the 066/067 camshaft specs. Both cams had the same intake duration, more on the 067 exhaust side. The 066 cam duration at .050" is 198/210/111 @ .050". The 067 is 198/213/113. The 068 cam was 288/302/115.5 adv. (212/225/115.5 @ .050") duration at the .406" +/- lift. The '71 YS 400 4-bbl had 8.2:1 adv. compression (7.8 actual). I wouldn't use the 068 cam with your stock factory compression and the 3.08 rear gear. It would work ok, but loose torque off-idle and the low rpm range you mostly drive/cruise in. If you change those (9.0+/3.42), then the 068 is better suited.

Forgot to say that you could use new 'stock' valve springs and your existing bottle neck rocker studs and jam nuts with any cam that has the stock .406"+/- lift.

Dennis

As a guide, I have the Summit 2801 (close to 068) in my 68 400 Firebird with #16 heads. My car is an auto with factory 3.08 posi. My compression is around 9.6 I would estimate given I used a larger valve relief piston. I like this cam but in my combo it doesn't really come on until about 2400 rpm, or about 45 mph. It would be perfect if I had a little taller rear end and/or a looser converter (like a 2200 or 2400).

In your combo, I agree with Dennis to not go bigger than the 067, or Summit 2800, or another similar aftermarket grind. Don't be afraid of having to go to and adjustable valve train with the 7/16 bbc studs. It is simple and better and opens you up to any cam.

Note: I think the Summit 2800 is on a 110 lsa. Not sure what that does vs a 112 in a low compression motor.

The Summit 2800 is ground on a 112 LSA; 2801 a 112; and the 2802 a 114. Here is a comparison of three stock 400's we built and dyno'd in the last 4 years. It's interesting how close they were in power regardless of valve size, compression, cam choice, and exhaust manifold type.

Dennis

First off -- thanks once again to all of you for the many times you've helped me with issues like these for nearly two decades on here. Appreciate it, truly.

Okay, so the mission as I see it is to get the closest grind I can get to a GM 9779067 like it originally had, preferably in a cam-and-lifter kit since my machine shop insists that I use new lifters made to work with the new cam.

(Incidentally, the heads now have ARP rocker studs and the locking Allen bolt nuts, though it's still running the stock rocker arms.)

The Howards unit they call a "Near duplicate of the Pontiac Ram Air I/II 375HP/400 cam (GM# 9779067)" -- product no. 417701 -- has these specs:

Basic RPM Range: 1600-5000
Intake Duration @ .050": 198
Exhaust Duration @ .050": 208
Advertised Intake Duration (@ .006"): 271
Advertised Exhaust Duration (@ .006"): 280
Intake Valve Lift with OE Rocker Ratio (1.50): .404"
Exhaust Valve Lift with OE Rocker Ratio (1.50): .408"
Intake Lobe Lift: .269"
Exhaust Lobe Lift: .272"
Intake Valve Lift with 1.55 Rocker Ratio: .417"
Intake Valve Lift with 1.60 Rocker Ratio: .430"
Intake Valve Lift with 1.65 Rocker Ratio: .444"
Exhaust Valve Lift with 1.55 Rocker Ratio: .422"
Exhaust Valve Lift with 1.60 Rocker Ratio: .435"
Exhaust Valve Lift with 1.65 Rocker Ratio: .449"
Lobe Separation Angle: 111 Degrees
Intake Centerline: 98 Degrees

The Melling SPC-5 is very similar:

Advertised Exhaust Duration 280.0 Degrees
Advertised Intake Duration 272.0 Degrees
Cam Type Hydraulic Flat Tappet
Computer Controlled Compatible Yes
Exhaust Duration at .050 inch Lift 208.0 Degrees
Exhaust Valve Lift 0.408 in
Intake Duration at .050 Inch Lift 198.0 Degrees
Intake Valve Lift 0.404 in

Do either / both of these seem like a good fit for '71 Formula 400 auto with original heads / intake / exhaust manifolds / 3.08 / Quadrajet?

Imo, I think the Summitt 2800 would be a great choice, especially since you already have the adjustable valve train. It has a little more lift built into the lobes than a stock 067. There should be no problem using the original rockers. I have my original stamped steel rockers on my 68 with the 2801 cam, and on my 71 TA with a cam closer to a RAIII specs.

Don't go by what the advertised RPM range is. I don't believe that a smaller cam than the 2800 is going have a broader or higher power band, all else being equal.

68bird, is there a set of lifters Summit makes to go with this 2800?

I thought they used to sell as a set, but apparently not anymore. You don't need anything special. When I did my 71 TA motor, I just used Johnson lifters which were a nice quality stock replacement. Nowadays, I am not sure if they are still around, or still USA made, or, what another recommendation would be.

Summit still offers the 2800 cam & lifter kit. It will work fine with your factory rocker arms and poly locks. Both 400 engines in the comparison I posted are using the 'kit' supplied lifters without incident.

Dennis

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.