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Discussion Starter #1
how hard is it to switch to a roller cam? What is involved in retro fitting a non roller block? Least expensive way to do it?

Thanks all
 

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Not really that hard to do. Basically it is just like changing any cam. The bad part is your going to have to buy some high priced lifters since the block was not set up for factory roller. The only other thing you will have to make sure your valve springs are up to snuff to match the new roller cam and you may have to change the gear to a steel one if your is a cast iron one.
 

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I can tell you for a Cleveland its a load of money and now that its done, IMO it wasnt worth it. Should have just installed a solid flat tappet cam. There are benefits if you're primarilly racing it and want big numbers. But a street grind roller cam wont give you much of anything in the seat-o-the-pants O-meter.
 

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Very easy, and can be done cheap but then you have to run a reduced base circle. You can retrofit it so that it fits a standard base circle with some verticle link lifters like I did, but let me tell you it ain't cheap.
 

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Are you interested because you want to keep the original engine for numbers matching?
Edit: I just realized your car is not original or stock, but hey, maybe you were asking for a friend..

If not, you may have more of a cam selection by switching to a 5.0 (or roller) block.
Edit: that would be my choice with your car
 

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Try and get a hold of the Sep '05 issue of PHR. Vizard has an article in there on street cams. He did some Spintron and dyno testing of flat tappet vs roller (hyd & solid) with some interesting conclusions drawn.

There are instances where converting an early block to accept a roller cam is going to give you more/better performance, but certainly not in the majority of street car applications.

And once you factor in cost per hp gained....well, I didn't do it on my 331 anyway.

But that's just me. ;)
 

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I second that. I've read the same article and similar articles on the net. A roller cam needs to have more the 270* advertised duration to make MORE power then a hydraulic flat tappet. Stock factory roller tappets are all done by around 6,200 rpm. Roller tappets have to deal with side thrust loads that will distort their body causing massive bleed down to the point where power takes a noise dive coupled to their heavy weight. Sure, you're going to find people saying that they've spun their stock roller cam motor well past 6,200 rpm but are they making power?

Factory roller cams do have less friction but I don't think it's all that less. Remember you're using a very mild cam profile. The more radical the profile, the stiffer the valve springs, the more resistance you have. The main idea of the roller tappet is to follow a very agressive profile. A while back I read something interesting about engine friction. Approximately 75% of friction comes from the piston and ring package. The numbers I seem to recall and I could be wrong but for a flat tappet cam is good for about 14-16% and the rest from bearings. So just how much less friction are you reducing by roller cam? Even if the numbers are flipped between bearing friction and cam friction. In an article, I think it was on Hardcore 5.0, there was a good cam article as well. In this article they said a Ford engineer reported that with all things being equal, with regard to the flat tappet and roller cam used in the 84 vs 85 Mustang that there was a neglable difference in power. I think Joe know's this article very well ;) and can say something as well.

Bottom line, I personally am not convinced enough to go to a roller hydraulic. I'd rather pick a good flat tappet hydraulic with behive valve springs and spend the difference of what going roller would cost toward a set of good heads. ::

I just want to add that if I were going to use a hydrualic roller cam, I definately woouldn't use factory tappets, I'd invest in a set of quality aftermarket such as Crane's billet body roller tappets. The the RPM range would be as much of an issue other then the addtional weight over a flat tappet but again, the behive valve springs would do wonders. The reason behive spring are good is that they have a poorly defined resonant frequency, meaning they won't fail to control at a specific frquency that would cause them to get a harmonic vibration and loose effectiveness, everything has a "natural" frequency in which they will vibrate. Also they are disgned to go into a controled coil bind progressively, and progressively increasing spring rate to control valve action. GM spend millions in developing them and Comp Cams has taken it one step farther.
 

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Discussion Starter #8
Thanks for all the comments. The reason I ask this question is after playing with Dyno2000 a 347 with trickflow track heat heads 9.7:1 compression small tube headers and a 600 cfm carb with my hydraulic flat tappet XE268H cam it shows I get max HP of 372 @ 5500 and max Tq of 399 @ 4000

Now the same setup using the XE266hr I get max HP of 414 @ 5500 and max Tq of 444 @ 4000 a qain of 42HP and 45 ftlb of torque. Thats a healthy increase if the program isn't lieing.

Any thoughts??
 

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Discussion Starter #10
Thx Joe but those are chevy cams so they don't compare to well. the chevy 268h a whole different beast from the xe268h i have the lift is way different. I know you use a different engine program than me. If you want I can give you all my specs and you can run it thru yours?
 

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I'm at work right now so I'm not able to run the program I have.

But, just so I'm clear, what performance level are you trying to reach? Would 300+ hp at the rear wheels get the job done for you?

Meanwhile, here's a couple of scans of a relevant portion of Vizard's article:

http://www.fordmuscle.com/pics/mstngjoe_Vizard1.jpg

http://www.fordmuscle.com/pics/mstngjoe_Vizard2.jpg

FWIW, this particular testing was done on a Ford 302 IIRC. Tom may be able to confirm that, as I don't have the mag in front of me right now.
 

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The 347 I'm having built is a roller for one simple reason: I don't have to worry about wiping a cam lobe (a VERY common problem nowadays).
 
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