Does anybody know what the exact specs are on the Hyper Pac Cam? What I'm looking for specifically is Intake and Exhaust duration. Intake centerline and Lobe Centerline. Thanks

The factory Hyper-Pak cam is an RDP design (Reverse Dual Pattern) with 276 degrees of duration on the intake and 268 on the exhaust. The cam has 52 degrees of overlap.

I have never seen the actual centerline numbers but based on road test reports, I would say that it was ground around 104 degrees intake centerline and most likely a little more (wider) on the exhaust lobe centerline, in order to reduce the amount of overlap.

In general, the Hyper-Pak cam was (is) not a "streetable" cam, it was designed to maximize the power of the long ram intake and special exhaust manifolds... at 4500 RPM, to help the Daytona compact cars come off the in-field corners a little stronger... and still rev high on the high oval banks. Low speed engine operation was not a factor.

Bottomline, that is a "purpose-built" cam grind for NASCAR compact car racing and it will be a hard cam to reproduce. ( who knows where the original lobe profiles are and who knows if anyone has an original cam to copy the profiles off of)

So the question is, what engine are you building and what will it be used for? You will need the right cam (and compression ratio) for that application and there are a lot of good options to choose from.
DD

It's amazing that the Chrysler engineers knew that more intake duration was better, and somehow that knowledge was not passed on effectively, even to Mopar Performance/Direct Connection.

Lou

_________________
Home of Slant6-powered fun machines since 1988

Doc, your RDP cam that you and Erson worked out is based on the Hyper Pak idea but made streetable??

_________________
Chris'
Autobody
Restoration
Service

Yes, many of the racers (including myself) have seen performance improvements with RDP grinds.

I also see a big gap between stock to near stock cam grinds and "performance" cams offered by the aftermarket.
Many SL6 owners, looking for a "street performance" cam usually end-up with a performance cam with too much lobe profile and overlap, which kills idle quality and low RPM power.

When the Erson group buy came along, I sent Erson a number of profiles and we designed 2 different RDP cams that have good "street manners" and a broad power band, in the 2000 to 5500 RPM range.
DD

Erson also made another RDP cam for me, which is bigger than Doug's, but I consider streetable with a mildly higher than stock stall converter. I haven't tried it yet, but will soon in my '68 Dart.

280/270 deg duration
226/220 deg duration @ 0.050"
0.465" lift on both
108 LSA

I will centerline this at 100 deg.

I have a 2100 stall (lockup) in this car, which should work fine, although 2400-2600 would be better. 8.8:1 comp.

Lou

_________________
Home of Slant6-powered fun machines since 1988

Okay to answer the question. I am building a 65 Valiant to stomp my roommates ford 302. He doesn't think it's possible but I know better.

Any suggestions would be appreciated.

Right now I'm thinking about boring .040 over and maybe shaving the head a little. If I can't find any Duals I'll make my own out of spare parts I have laying around.

Doc & Lou, thanks for the info but I'm feeling really cam stupid. I know there are a whole lot of variables but it would be nice to have some general guidelines when selecting an Erson cam. I thought the 270 would be as healthy as I would go on the street. But I'm wondering if an RDP grind would work well with my Hurricane intake? I know I haven't mentioned a lot of other criteria. My first attempt at this was under a post called: Virtual engine build - advice welcome!" Got some good advice but still feel like a major Gomer in the cam dept. Bet I'm not the only one who could use a cam tutor when it comes to the Erson choices. Thank, Wayne.

_________________
66 Lil' Red Piggie Valiant (Mater Crusher) - Thanks Zilla!!!!! 72 Demon (Number 1 Son's)

Wayne,

This is a complex topic with lots of things factoring in.

Can you run a high stall converter? If so, that will open up a lot of cams to be "streetable." I consider up to 2800-3000 stall to be very street friendly since modern stall converters are quite efficient.

Lou

_________________
Home of Slant6-powered fun machines since 1988

Lou, thanks for the reply. Yes, I can run a "high" stall and am very lucky to have a top notch transmission guy who is a Mopar fiend!!!!! I am constantly thinking/rethinking my engine and car build while I slowly acquire parts! I know this is complex and that is why I am thankful for the help!

_________________
66 Lil' Red Piggie Valiant (Mater Crusher) - Thanks Zilla!!!!! 72 Demon (Number 1 Son's)

Here's what I posted for Guzzi Mark, which would also work well for you.

Mark really needs a bigger cam than this, BTW.

"234@0.050" intake and 226 exhaust. See if Erson will do this for you. Use LSA of 106 and centerline at 100 deg."

I would use 108 LSA for the street and a 2600-3000 converter.

Lou

_________________
Home of Slant6-powered fun machines since 1988

How fast is his Ford to start with? I regularly knocked off stock 5.0 Mustangs at the strip when my car was running mid-15's, and I didn't have a ton in it. If he's running low 14's or quicker you will have to spend considerably more money.
Right there you have the makings of a 17 second car.

_________________
Official Cookie and Mater Tormentor.

Lou thanks! Still trying to digest this, so I will PM you or ressurect the virtual engine build thread so I don't steal this one! Thanks, Wayne.

_________________
66 Lil' Red Piggie Valiant (Mater Crusher) - Thanks Zilla!!!!! 72 Demon (Number 1 Son's)

We don't know how fast his mustang is yet. We just finished his engine and have yet to put it in his car. We haven't even started the body work yet. It's still on stands in the garage.

If the Valiant is currently running, that's makes your car faster in my book.
DD