Pontiac cam question

[Bonnewagon]

Worse, this motor is an unknown. It may be stock because of the smooth idle. But there is a stuck lifter clacking away and it may end up with a new cam/lifter set. If so I want a streetable cam that is OK in traffic. Much more to investigate like rear gears, etc, and I just wanted to know what type cam worked best with headers. I read that a dual pattern may have too much overlap and bleed off torque and a single is better on the street. Each cam company seems to have their own ideas.

 

[pontiac guy]

I say yes to the hedders. Yes dual pattern.

 

[bracketchev1221]

6X. I see that the 067 specs are used on many similar cams, even the '78 W72, just with a little less lift. But only a few companies make it. They are making the RA IV and 455SD cams as if everyone is racing. I don't want to go more than 272 adv. duration.

I wouldn’t worry about advertised duration it means nothing. Look at the .050 duration number.

 

[motorheadmike]

You need to look at the intake/exhaust flow ratio. The worse it is the more you have to bias to the exhaust. It is important to note that exhaust flow is less significant than intake flow because it is being forced out of the cylinder versus intake flow which is being drawn in.

Then you should consider the flow at various lift points, and consider that peak flow figures are only seen once seat-to-seat - but the valve will see the low and mid lift figures twice. This is where lift and duration come into play.

Then you need to choose the amount of overlap for your intended application. Too much is going to work against you.

A simple exhaust split isn't going solve your issue. Neither will an RV cam.

 

[fleming442]

I'd call a pro builder. I'm not a fan of single pattern cams. The way I see it, singles were the technology at the time. There's been a ton of r&d over the years, and the Pontiac specific guys know what works. When I had my Olds 468 built, I called Bill Travato- long time Olds builder, been 7.85 Olds powered. I wanted a hydraulic roller, and he spec'd what I consider a puny cam (.491/.510, 236/242 on a 110). Sumbich is 497 at the wheels doing 1/4 mile math.

 

[Bonnewagon]

Well the factory used dual pattern cams even with the cast iron RA/HO manifolds. And they flow almost as good as headers. But they kept the lift rather low so as not to strain the valve train and because the 30° valve seats flowed well at low lift. My old TA used the Crane HMV260-2 cam and it was terrific on the street because it was a low rpm grunt monster. It was 260/272- .427/.454 and worked with stock springs. That is why I was thinking the 067 would be a notch better being 273/289 duration.

 

[pontiacgp]

Martk, I had a 74 GP with the Pontiac 400. Back then I had the money but no place to work on the car so I sent it to a reputable shop to get more power out of it and they suggested and put in a Crane Econo cam. I had no headers but dual exaust and that cam woke it up pretty good and if I kept my foot out of it the gas mileage was great for that car. I am going by memory and we all know how that works but I don't think I exagerated on this one. I did get clocked in that car at 143 mph, It had 2.78 gears

 

[Bonnewagon]

Steve, my cam is indeed a Crane Econo-miser that was common in the late '70's- early 80's. It is a high lift- short duration cam that is perfect for a heavy street car. I first had it in a Pontiac 350 I swapped into a '68 Firebird 4 speed. It was pretty lumpy in the 350 and really put out the bottom end grunt. The same cam in my '77 TA 400 4 speed was more tame due to the larger displacement. It was out of breath at 4000 rpm. That is why I would step up to a bit longer duration in a 400. I have a 278° duration Crane in another 400 and it is borderline street needing a vacuum can for the brakes. I want to avoid that so the 266- 270 range seems perfect. I know- I know- advertised duration is not as accurate as @ .050" but my old brain doesn't "see" @ 050" values in my head. I think it would be 200- 210° @ .050"?

 

[Northernregal]

When I built my 462 I talked to these guys about this cam. Yes the roller conversion is pricey but it’s a torque monster.
http://www.sdperformance.com/viewProduct.php?productID=1815

I also talked to Cliff Ruggles and he said 067 with around 10.5:1 static compression. Said That was a magic number for a poncho with cast Ram air headers and an edlebrock performer Rpm. Always a winner.

 

[bracketchev1221]

Steve, my cam is indeed a Crane Econo-miser that was common in the late '70's- early 80's. It is a high lift- short duration cam that is perfect for a heavy street car. I first had it in a Pontiac 350 I swapped into a '68 Firebird 4 speed. It was pretty lumpy in the 350 and really put out the bottom end grunt. The same cam in my '77 TA 400 4 speed was more tame due to the larger displacement. It was out of breath at 4000 rpm. That is why I would step up to a bit longer duration in a 400. I have a 278° duration Crane in another 400 and it is borderline street needing a vacuum can for the brakes. I want to avoid that so the 266- 270 range seems perfect. I know- I know- advertised duration is not as accurate as @ .050" but my old brain doesn't "see" @ 050" values in my head. I think it would be 200- 210° @ .050"?

I don't know if he's still around but try looking up Nunzi's performance. He was the big NY Pontiac guy.