flat tappet to roller cam - Page 2 - Hot Rod Forum : Hotrodders Bulletin Board
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  #16 (permalink)  
Old 05-22-2004, 06:31 PM
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didn't say anything about compression or gears on either of those 2.
first said "biggest for stock stall"
second said "2000+ stall"

I can always use 1.6:1 roller rockers to get more life

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  #17 (permalink)  
Old 05-22-2004, 06:38 PM
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True, but you can get even more lift if you start with a cam that has higher lift. The higher the effective lift possible within a given duration the better.

Here is another good one from Crower:
http://www.crower.com/misc/m_cat.shtml

It is five sections down on page 26. Look for the 216HR224 cam.
The specs are:
114o lobe sep
278/286 advertised
220/228 @ .050"
.498"/.519" lift
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Old 05-22-2004, 08:40 PM
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I have to agree.Unless you want to go with a LOT more lift for the given .050" duration you wont make much more power with the roller cam.I get a kick out of the test Car Craft just did.It pretty much tells the story of the results I have seen only they were impressed by them.They had a flat tappet smallblock that was a decent street combo with stamped 1.5:1 rockers on it.They stabbed a similar duration at .050" roller in it but went with both the roller cam AND 1.6 rockers roller rockers.They ended up with a flat tappet that had /480" lift running against a roller that had about .525".They only picked up about 15 hp.Had they simply swapped the 1.6:1 roller onto the flat cam they would have found close to 10 of those horsepower,and if the roller rocker design itself was even worth another 1 or 2 hp we might have been looking at a 3 hp gain from the roller cam itself!!These results are pretty typical of what I have seen when swapping from a hydraulic flat tappet to a hydraulic roller.Any gains a builder claims might be from the flat tappet cam being the wrong cam to begin with.
The limit to camshaft action on a chevy with hydraulic lifters is the lifter body itself.You cant run enough spring pressure to get really fast ramps on either type of hydraulic lifter without bleeding down the lifter itself.The possiblility for valve acceleration with a flat tappet smallblock is really pretty impressive.A lot of people are afraid of wiping the lobes out but you have to remember that the same lifter with the same contact area is used on bigblock chevys with 1.7:1 rocker ratios and valve lifts well into the .680" range and failure isnt really an issue,and that is on an 8000 rpm motor with monster triple springs.You shouldnt have a problem running a 1.6:1 rocker on a smallblock flat tappet cam and getting .550" lift at the valve without reliability issues.
As for a Juice roller,try the GM "hot" cam with 1.6:1 rockers on the intake side.Good luck.
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Old 05-22-2004, 08:47 PM
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Other points to bring up are that the roller cams reduces friction, and also that roller lifters are heavier than flat tappets. Just some things to think about.
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Old 05-22-2004, 09:09 PM
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well then what about the solid roller cams? I noticed you were talking about the lifters bleading off due to spring pressure. What I was mainly looking at was that roller cams have longer duration at max lift then flat tappet cams. Also the cut down on friction.
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Old 05-22-2004, 09:11 PM
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Solid rollers aren't as good for the street. Solid rollers will make the most power, and have the highest RPM potential.

If I were you I would stay with the hydraulic roller. You would have to have a pretty solid (expensive) bottom end to really take advantage of a solid rollers capability.
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Old 05-22-2004, 09:14 PM
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I was thinking of using a hydraulic roller cam since they have the specs I want, but with solid roller lifters to prevent the blead off super streeter was talking about. Would that be feasible?
Also, should I modify my heads for this?
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Old 05-22-2004, 09:22 PM
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You will be fine with one of the cams we were discussing. If you were to get springs that were way heavier than what you need, it may become more of an issue.

You should get the recommended springs with the cam you end up selecting. As far as modifying the heads, it won't be necessary.
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Old 05-22-2004, 09:29 PM
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ok cool, I had an extra set of 441 casting heads off of my old 350 in my chevelle. I was just going to get a regular valve job done on them and get them cleaned up. I was just wanting to make sure I didn't have to get the works done on them. I know they're smog heads, but I don't know exactly what the difference between smog heads and non-smog heads are.

also, what kind of horse power / torque gains would I be looking at. It has the stock flat tappet hydraulic cam in it now.
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Old 05-22-2004, 09:42 PM
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Well, if the heads are off the engine then I would recommend clearancing the pushrod slots for 1.6 rockers. You can do this with a Luis tool or with a die grinder. You want more clearance at the sides closest to the exhaust ports of the pushrod slots.

The reason for doing this would be that if you want to add roller rocker arms later you will be able to just bolt on a set of 1.6 rockers. The only way to clearance for this is with the heads off. This is not a necessary mod, it is just in case you might want to upgrade later. It is up to you.

The gains are hard to estimate. It could be anywhere from 5 hp to 50 hp. Maybe more, who knows. There are too many factors to guess. The odds are your favor though for a significant gain.
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  #26 (permalink)  
Old 05-22-2004, 10:26 PM
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would doing the clearancing be expensive?
I do want to run full roller rockers 1.6.
also, what does a 3 angle valve job cost, I heard that those help out a lot.
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Old 02-05-2007, 06:45 AM
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http://www.idavette.net/hib/camcon.htm

read all the way thru this carefully
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  #28 (permalink)  
Old 02-05-2007, 08:11 AM
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Spend the money on a good set of heads and use a cheap flat tappet cam. This will give you the best results for each dollar spent.

There isn't much difference between a mild roller cam and a mild flat tappet cam, especially when using stock heads.
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  #29 (permalink)  
Old 02-05-2007, 11:27 AM
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cam

Guys look at the orginal date....


I think he made a choice by now L.O.L.

Keith
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  #30 (permalink)  
Old 02-06-2007, 06:06 PM
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Fact is, flat tappet chevy cams of about 220* or less accelerate faster than rollers off the base and the roller doesn't have time to catch up. Area under the curve is about the same. According to CompCams.
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