351w cam upgrade?

cam research is the shop many have chosen for grinding ford cams...they can fab RR cam as well

Which is not RR

Yes. I was looking at some lunati "voodoos" but Tim was strongly talking me out of them.

They should be able to duplicate the same cam in RR I would assume. I think lift was .490 and duration at .050 was in the 220 range.

The person who has all the good info,Tim, has not been on all morning.I'm afraid he's out dancing with Sandy,hope everything is ok.
I know he always says Cam Research is conserative on their recommendations. My Crane from 20 yrs ago is 260* on the intake 272 on exhaust.Lift is 456 on intake and 484 on exhaust. No lobe seperation is listed.

That is correct from other postings I've seen him put up. Separation was 110.

I figured it would be just on the threshold of a lope and no lope. The dual pattern cams are generally more behaved at idle than old school single pattern with more overlap. I'm considering going with something more modern in my car. Guess im getting old haha. My car sounds like it wants to kill other cars haha.

phatsat67 wrote: They should be able to duplicate the same cam in RR I would assume.

...And that is where you'd be wrong.

As far as Ive been able to tell, there is only one type of reverse rotation Windsor core out there. LSA is fixed at 112, and due to their size and heat treat, there are limitations on the blank as to how far you can go with lift (and subsequently, duration). Cam Research isnt comfortable grinding anything more aggressive than their common .460 grind (1.6 rockers), so not much more aggressive than stock (~.450). Lunati will grind you something a bit more aggressive (in the neighborhood of .500) but I suspect that theyre pulling from the same group of cores as everyone else, and are simply willing to push the envelope on reliability a bit. Not a gamble I like very much.

The common .460 grind with 1.7 rockers will get you in the .489 ballpark. Not a bad place to be, and as Alan saw on his '81, can run pretty darn well. Not a bad match for the common ~325hp GT40p head upgrade, IMHO. If you want to make >1hp/ci, then Id be looking to spend the money to go roller.

None of the cam sizes in question will give any hint of lope, at least not that Ive experienced. I know Hotboat was running something way wilder in his hot 351w (north of .550). Reid had something pretty stout in his 347 as well. We're north of .600 on our big block, and thats got some lope to it... but thats a whole different ballgame.

Youre correct, duration causes the lope... but obviously its closely related to lift and the 2 will travel together- especially on flat tappets, which simply cant handle the aggressive ramp rates that rollers can.

My understanding is that the ramp rates on rollers are almost 25-30% better than flat tappets.

Of course the lobe separation adjusts your power band as well. I'd say a 112 degree lobe separation isn't bad for the RR cams and Tim's suggestion on running a 1.7 rocker ratio is really good advice.

For those of you interested....the Tim Benjamin cam specs....
RPM Range: 2500-5200
Duration @.050" (I/E): 218/222
Lift w/ 1.6 Rocker (I/E): .490/.490
LSA: 110 degrees

I'm surprised this doesn't lope Tim, I've had cars with similar grinds and they loped a bit. But that's a subjective way to describe it really. All engines will lope. It's just a matter of what RPM they are going to do it at.

And for the record Tim...I've seen the video of your BB and it lopes more than just a bit.

Here is a link to the cam specs on this site.


351w cam specs

TX Wind wrote: Here is a link to the cam specs on this site. http://www.correctcraftfan.com/forum/forum_posts.asp?TID=5627&title=351w-cam-specs

Link is broken.

Ahhh Silly camshaft blanks! Yeah the overlap and duration cause lope and also determin where the engine will make peak power/torque.

Lift needs to match up well with the flow numbers of said head. I can't see a stock GT-40p or GT-40 Port needing much more than the numbers Tim posted with the 1.7 ratio rockers(unported configuration). A lot of times too much lift will effect port velocity and make less power.

The key is in the total power package. Well matched parts to one another.

The advantage of roller camshafts is less friction and more aggressive ramp rates as Tim stated. The more agressive ramp allows the valve to achieve max lift much sooner than a flat tappet application and allows. It also allows the valve to stay closer to that max lift number longer.(although duration can be the same as a flat tappet application). Valves stay open the same ammount of time but roller achieves greater flow because of its ramp rates.

With rollers you don't have to worry about wiping off a lobe at first start up or running ZDDP in your oil.

I'm considering a roller swap in the car to keep the power but gain drivability.

Thanks for the info. Cant really see going more than .500 on lift w/ P heads, due to the fact that flow drops off .... Just wasnt sure how much duration I can get away with, especially since I dont want to suck water into a cylinder.
I wouldnt mind a bit more lope at idle,.. I'm not passing emmissions or needing vacuum to power accessories like a car. Performance on a budget is what I'm after.

Hey Jeff, just noticed your comment above.....

I have the GT-40 in my '99 Sport and while it doesn't have a ton of hours on it, they are working hours, so I suspect an overhaul will be in order in the next few years....

With that said, with it all apart, would your recommendation, for course and wakeboard use, be to go with P-heads, cam and rockers during the rebuild.

It would seem the most bank for the buck and certainly a significant power increase over stock....

Thanks,

Mark