[Nap]

I have two questions on the cam that came in the W72 Motor. How close was the grind to the Pontiac 068 cam? What would be the difference in horsepower and torque in an otherwise stock W72 motor if you installed a Pontiac 068 cam?

[Nap]

I have two questions on the cam that came in the W72 Motor. How close was the grind to the Pontiac 068 cam? What would be the difference in horsepower and torque in an otherwise stock W72 motor if you installed a Pontiac 068 cam?

[MalteseFalcon]

I was able to find only this info; actually the W72 looks closer to the 067 cam (273/289 & .403/.406)

W/W72- #10003402
Intake open@21 close @73 duration 274 Lift .364
Exhaust open@77close@41 duration 298 Lift .407

068
Intake open @?? close@?? duration 288 Lift.414
Exhaust open @?? close@?? duration 302 Lift .413

Steve

[MalteseFalcon]

I found that John Witzke POCI Tech Advisor, has written an article in Smoke Signals on the specs of the W72 camshafts. Mr. Witzke has forgotten more about the W72 engine than most of us will ever know. Apparently there were differences between manual and auto transmission cars in 1977, and 1978 may have been different again, or it may have been one or the other of the 1978 models. In that article, he said "In case anyone was wondering, testing has shown the number 549112 camshaft to be a little more aggressive in making power than the 549431 camshafts. In fact, both are better in most ways at making power than the 066 and 067 camshafts, which were used, in some earlier Pontiac performance engines."

Published specs are as follows:

1977 Automatic Transmission W72 Camshaft Specifications
Possible 1978-79 W72 Camshaft Specifications
Part # 549112

Intake Duration 274 Degrees
Open 16 Degrees B.T.D.C
Close 78 Degrees A.B.D.C.
Lift .364
Intake Centerline 121 Degrees
Exhaust Duration 298 Degrees
Open 79 Degrees B.B.D.C.
Close 39 Degrees A.T.D.C.
Lift .364
Exhaust Centerline 110 Degrees
LSA 115.5 Degrees
Overlap 55 Degrees

1977 Manual Transmission W72 Camshaft Specifications
Part # 549431

Intake Duration 274 Degrees
Open 21 Degrees B.T.D.C
Close 73 Degrees A.B.D.C.
Lift .364
Intake Centerline 116 Degrees
Exhaust Duration 298 Degrees
Open 77 Degrees B.B.D.C.
Close 41 Degrees A.T.D.C.
Lift .364
Exhaust Centerline 108 Degrees
LSA 112 Degrees
Overlap 62 Degrees

Steve

[Nap]

Steve:
Thanks for the info. I'm just trying to get a better feel for the horsepower my W72 is generating. The engine builder put a cam with the following specs in it:
Duration @ .050, Int.214, Exh.224
Lift 1.5 to 1, Int.445, Exh 465
LSA 112
Intake centerline 107
He estimated it to be 335. Not sure if that is at the crank or flywheel.

The specs are almost right on for the 068 for duration. The big difference is in the lift numbers.

Thanks,
Nap

[John Witzke]

Nap, The subject appears to have been well covered by MalteseFalcon and I answered this same question that you posted on transamcountry. BTW thanks Maltesefalcon for the words.

John Witzke
Member Society of Automotive Historians
POCI Tech Advisor
1977-79 W72 Performance Package Historian

[MalteseFalcon]

I'm not sure how to estimate the HP from that cam. As you say, it seems to be similar in some ways to the 068 but with more lift. The L-74 (Ram Air III) engine used the 068 cam and it was rated at 335 HP (Gross, i.e., at the flywheel without mufflers or accessories), but it also had 10.5:1 compression and HO manifolds. The W72 was rated at 200 (net) in '77 and 220 (net)in 1978, but probably was under rated - NRHA refactors it to 290.

So would changing to essentially the same cam alone make a W72 match the output of a RA III? I doubt it. But maybe it would with with headers and better exhaust, the net HP might be similar. That's just speculation, though. I'm sure there are others on this board who could give you an estimate based on the details of your combo.

Steve

[Nap]

John:
Thanks for your reply on both boards.

Steve:
I think I might be very close to the RA III ouput.
Between having the extra lift the cam provides over the 068 cam and the compression was raised from the stock 8.1 to 1 to 9.25 to 1 it just might pretty close. Besides I'm running D port RA manifolds and 2.5 duals thru an x pipe.

Thanks.

Nap

[MalteseFalcon]

Nap, Based on that I'm sure you must be close.

Steve