351w cam upgrade? |
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Waternut
Senior Member Joined: July-11-2012 Location: Macon, GA Status: Offline Points: 292 |
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Posted: October-29-2012 at 11:04pm |
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Just curious if anyone has upgraded their camshaft on these reverse spinning engines? I've got a carbureted 351w PCM that I recently put GT40P heads on. I'm getting ready to pull the engine this winter to fix the floor and will be checking the engine over. Just looking at options for cams while everything is apart.
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kapla
Grand Poobah Joined: March-27-2008 Location: BA, Argentina Status: Offline Points: 6148 |
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cam research is the shop many have chosen for grinding ford cams...they can fab RR cam as well
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<a href="">1992 ski nautique
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phatsat67
Grand Poobah Joined: March-13-2006 Location: Indiana Status: Offline Points: 6151 |
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You will probably want to look at the cam spec that Tim B is running in his 90. He will chime in. It's a cam research Flat tappet grind. Not a lot of duration so idle quality and drivability stay top notch.
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Hollywood
Moderator Group Joined: February-04-2004 Location: Twin Lakes, WI Status: Offline Points: 13513 |
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Which is not RR
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Waternut
Senior Member Joined: July-11-2012 Location: Macon, GA Status: Offline Points: 292 |
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Sorry for the noob question but what is RR? Reverse rotating?
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Hollywood
Moderator Group Joined: February-04-2004 Location: Twin Lakes, WI Status: Offline Points: 13513 |
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Yes. I was looking at some lunati "voodoos" but Tim was strongly talking me out of them.
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fumanchu
Newbie Joined: July-13-2012 Location: norcal Status: Offline Points: 24 |
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I'm in the same boat, can we get some actual duration and lift numbers?
Mine motor is standard rotation so I could technically get an off the shelf grind. I will stay away from the XE grinds Comp has, heard way to many bad things. |
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'89 2001
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phatsat67
Grand Poobah Joined: March-13-2006 Location: Indiana Status: Offline Points: 6151 |
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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.
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fumanchu
Newbie Joined: July-13-2012 Location: norcal Status: Offline Points: 24 |
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duration and lift numbers posted above are actually more aggressive than I would have thought. What about LSA? 112-110?
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'89 2001
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Gary S
Grand Poobah Joined: November-30-2006 Location: Illinois Status: Offline Points: 14096 |
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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. |
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phatsat67
Grand Poobah Joined: March-13-2006 Location: Indiana Status: Offline Points: 6151 |
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I think Tims was in the 110 range... Don't remember.
Gary your boat probably lopes a bit at idle? That cam is very similar to what I put in the 350 I built for the Skylark. I personally wouldn't want my main boat(the 86)to lope at all. I like smooth as silk on it but the Skylark is for fun so party on. |
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TX Wind
Senior Member Joined: March-29-2011 Location: near Dallas Status: Offline Points: 333 |
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That is correct from other postings I've seen him put up. Separation was 110.
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Gary S
Grand Poobah Joined: November-30-2006 Location: Illinois Status: Offline Points: 14096 |
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No Zach it does not lope at all. I wonder if thats why Tim says you can go some more?
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phatsat67
Grand Poobah Joined: March-13-2006 Location: Indiana Status: Offline Points: 6151 |
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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.
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TX Wind
Senior Member Joined: March-29-2011 Location: near Dallas Status: Offline Points: 333 |
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Tim was actually on the Mastercraft site talking about this somewhere. They had the factory cam grind numbers on the site. The earlier engines sported durations of 194 at .050 but the later engines were closer to 206 and the hp at 221. They say that after about 200 it starts to get a bit more lopey. I can say that is pretty accurate. I have one of each of those factory grinds.
I would guess that Gary's cam at .050 is closer to the 206, 221 dual pattern grind that was the middle of those. It has a noticeable difference in idle compared to the 194 as it has a faint hint of a lope like an RV cam grind but is still very smooth. Is that pretty accurate Gary? |
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TRBenj
Grand Poobah Joined: June-29-2005 Location: NWCT Status: Offline Points: 21169 |
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...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. |
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TX Wind
Senior Member Joined: March-29-2011 Location: near Dallas Status: Offline Points: 333 |
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Ahhh...there you are Tim. I was just looking up the postings on this from Team Talk. Here is what I gleaned from there
STD 351w camshaft specs Duration 206 int./221 exh. @ .050 Valve Lift 0.445 int./0.453 exh 115° HO 351w Duration 210 int./221 exh. @ .050 Valve Lift 0.453 int./0.453 exh 115.5° Correct me if I'm wrong Tim but it's not so much the lift that causes lope but the duration. I do agree with you on the roller though. You can get a great deal more lift with less duration. It keeps the idle smoother. |
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TRBenj
Grand Poobah Joined: June-29-2005 Location: NWCT Status: Offline Points: 21169 |
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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.
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Gary S
Grand Poobah Joined: November-30-2006 Location: Illinois Status: Offline Points: 14096 |
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Yes 204 and 216 @ .050 |
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TX Wind
Senior Member Joined: March-29-2011 Location: near Dallas Status: Offline Points: 333 |
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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. |
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Waternut
Senior Member Joined: July-11-2012 Location: Macon, GA Status: Offline Points: 292 |
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I have done a lot of research on cams in the last week or two so I'm sure I know just enough to sound like an idiot. It wasn't until last night that I realized that RR cams were different from standard which put a damper on my plans. From the sounds of it, I'm guessing there are no "off the shelf" RR cams available. Is that correct?
BTW when I was looking up standard cams on Summit Racing, I found that a lot of them have a couple videos that give, what I thought was, an excellent explanation of what all the numbers on a cam mean and do. |
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TX Wind
Senior Member Joined: March-29-2011 Location: near Dallas Status: Offline Points: 333 |
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TX Wind
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Waternut
Senior Member Joined: July-11-2012 Location: Macon, GA Status: Offline Points: 292 |
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Link is broken. |
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TX Wind
Senior Member Joined: March-29-2011 Location: near Dallas Status: Offline Points: 333 |
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Link has been repaired |
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phatsat67
Grand Poobah Joined: March-13-2006 Location: Indiana Status: Offline Points: 6151 |
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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. |
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phatsat67
Grand Poobah Joined: March-13-2006 Location: Indiana Status: Offline Points: 6151 |
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There is a guy that has done research for years on 440 6 bbl motors for pure stock cars(stock eliminator). He has the cams so well fit to the engine that it idles like a 318. Stock lift has to remain but he can alter duration, lobe seperation, ramp rates, and centerline, The cams take the cars from low 13 second cars deep into the mid 12's depending on driver and vehicle. Very impressive.
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fumanchu
Newbie Joined: July-13-2012 Location: norcal Status: Offline Points: 24 |
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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. |
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'89 2001
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TX Wind
Senior Member Joined: March-29-2011 Location: near Dallas Status: Offline Points: 333 |
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Quite honestly, if you take a look at Tim's cam specs and the factory ones there's not a lot of difference if you use 1.7 rockers. The big difference is in the lobe separation. The reason for this is that the tighter lobe separation gives more hole shot. So....a pretty close to stock grind with the 112 separation should give you a real nice match to Tim's cam if you use the 1.7 rockers. You will have a little less hole shot but a wider power band. If you're custom grinding one, you can probably ask for a tiny bit more duration but there's not much need for it. You're already gonna make about a 60 H.P. improvement by adding new rockers and heads. It should be pretty noticeable.
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ultrarunner
Platinum Member Joined: October-02-2005 Location: Ridgefield, Ct. Status: Offline Points: 1831 |
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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 |
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