Changing Rockers to rollers
Racer
Joined: Jul 2006
Posts: 277
Likes: 0
From: Big Spring TX
Conversion kit to handle the roller rockers? Never heard that one before. At most you would need tall valve covers.
Anyway, I say put them on if you want to. You would much more benefit from headers and a good exhaust, but roller rockers are a more efficient design and they definately aren't going to hurt anything.
But if you are wanting more get up and go, you need a better intake, headers, exhaust, cam, and heads.
And with all the vacuum operated items on a c3 you can't go too big on that cam.
Anyway, I say put them on if you want to. You would much more benefit from headers and a good exhaust, but roller rockers are a more efficient design and they definately aren't going to hurt anything.
But if you are wanting more get up and go, you need a better intake, headers, exhaust, cam, and heads.
And with all the vacuum operated items on a c3 you can't go too big on that cam.
Le Mans Master
Joined: Jun 2004
Posts: 6,231
Likes: 65
From: Seattle WA
St. Jude Donor '14
Melting Slicks
Joined: May 2000
Posts: 2,029
Likes: 63
Not a flat tappet engine but my L98 TPI 10:1 350cid 250hp went from 96.9mph to 102.6mph on 1/4 with only swapping mufflers and installing Crane Gold 1.6RR's. Cannot say which was more responsible for the improvement. But, probably most of the improvement rockers gave were due higher ratio rather than roller type.
Pro
Joined: Jul 2008
Posts: 699
Likes: 3
From: Millersville, MD
Not a flat tappet engine but my L98 TPI 10:1 350cid 250hp went from 96.9mph to 102.6mph on 1/4 with only swapping mufflers and installing Crane Gold 1.6RR's. Cannot say which was more responsible for the improvement. But, probably most of the improvement rockers gave were due higher ratio rather than roller type.
Less friction = Lower Oil Temp
Ratio Accuracy
Material/Weight
Higher Ratio = Increased Performance
Strength
Drifting
Joined: Feb 2005
Posts: 1,738
Likes: 2
From: San diego ca
Back when I had my 84 vette I recall articles that reported changing to 1.6 rockers (roller or roller tip) would produce power gains, if and only if there was additional flow in the heads at the higher lift numbers. Of course the benefits came from the increased lift and not the roller componant. The test I recall was on a 84 vette, switching to 1.6 rollers netted an increase of 12 hp.
Changing to 1.6 on the exhaust only was effective with factory heads due to the weakness of the exhaust port (prior to vortech heads)
Any gain from an accurate rocker ratio only was within the realm of statistical error on the engine dyno, i.e. going from 1.5 stamped to 1.5 roller was essentially a wash.
Oil temp reduction seems a logical inference given the difference between a roller rocker and a stamped rocker but I dont think I've seen any real world tests of the oil temp difference, I'm willing to bet oil temps reach the same levels, perhaps oil temps rise slower in motors equipeed with rollers.
On a stock, low rpm, low output motor, swapping 1.5 stamped out with 1.5 rollers is IMO, essentially pearls before swine.
Changing to 1.6 on the exhaust only was effective with factory heads due to the weakness of the exhaust port (prior to vortech heads)
Any gain from an accurate rocker ratio only was within the realm of statistical error on the engine dyno, i.e. going from 1.5 stamped to 1.5 roller was essentially a wash.
Oil temp reduction seems a logical inference given the difference between a roller rocker and a stamped rocker but I dont think I've seen any real world tests of the oil temp difference, I'm willing to bet oil temps reach the same levels, perhaps oil temps rise slower in motors equipeed with rollers.
On a stock, low rpm, low output motor, swapping 1.5 stamped out with 1.5 rollers is IMO, essentially pearls before swine.
Le Mans Master
Joined: Jun 2004
Posts: 6,231
Likes: 65
From: Seattle WA
St. Jude Donor '14
It's the ratio
Changing from 1.5 to 1.6 rockers increases lift by x1.067 - and that's significant. The duration also increases 2 degrees for every .1 change in ratio. If the heads can use the lift (i.e. there's flow capacity), there's power to be found here.
Changing from 1.5 to 1.6 rockers increases lift by x1.067 - and that's significant. The duration also increases 2 degrees for every .1 change in ratio. If the heads can use the lift (i.e. there's flow capacity), there's power to be found here.
Last edited by billla; Jul 16, 2009 at 10:31 AM.
Le Mans Master
Joined: Jun 2004
Posts: 6,231
Likes: 65
From: Seattle WA
St. Jude Donor '14
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Drifting
Joined: Aug 2008
Posts: 1,381
Likes: 11
*sigh* I'm out
The rocker design is terrible. Sure they made 90 bajillion or so, but that doesn't make it a good design! 3 pivot points that use a ball and socket (which is a poor way to keep things lined up). They did get it correct on the LS engines - but if the design from the early 1900s is so great, why did they change it?
If you are looking for material on dyno tests look at Popular Hot Rodding, Car Craft, Hot Rod, or any of the Chevy mags - they have all done the tests. And I have done it myself several times.
Bill - I said we don't see this the same and should let it go at that.
Are you so full of yourself that you just can't let it go at that?
Le Mans Master
Joined: Jan 2006
Posts: 6,504
Likes: 139
From: Butler Pa
Burning Brakes
Joined: Jan 2007
Posts: 1,057
Likes: 4
From: Concord Calif
The stamped steel rockers are a good rocker for a stock engine for sure. There will be and there is a power increase for going to a true roller rocker, why is because even at the same static ratio the steel rocker decreases the ratio far more than the roller, as the rocker moves to open the valve it also slides back on the ball and really looses lift, where as the roller has no way to decrease ratio other than moveing toward the piviot point but that is a minimal lose. Now can you feel the power increase by the seat of the pants? Really the number can't be seen on a dyno for sure as the increase or decrease is well within the margin of error for any dyno. But the added strength and stabili
ty is well worth the cost on a hot rod!!
ty is well worth the cost on a hot rod!!
Le Mans Master
Joined: Jun 2004
Posts: 6,231
Likes: 65
From: Seattle WA
St. Jude Donor '14
And happily,so did the OP Not sure why you singled me out from all the posters that disagree with you, but in any case I guess some people just can't disagree without being disagreeable.
Last edited by billla; Jul 16, 2009 at 10:35 PM.
Melting Slicks
Joined: May 2007
Posts: 3,246
Likes: 4
From: Bay Area CA
If your cams good, get some vortec heads, some true rollers, and some headers, These heads come with an intake, you can get away for about 1500, do the work yourself, don't have to pull the radiator, H/B, fuel pump, still a bit of work, but you'll be grinning from ear to ear.
http://www.sdparts.com/product/SD806...formerRPM.aspx
http://www.summitracing.com/parts/BIG-31106FLT/
they come with new stamped steel rockers.
http://www.sdparts.com/product/SD806...formerRPM.aspx
http://www.summitracing.com/parts/BIG-31106FLT/
they come with new stamped steel rockers.
Last edited by RunningMan373; Jul 16, 2009 at 10:46 PM.
Le Mans Master
Joined: Jun 2004
Posts: 6,231
Likes: 65
From: Seattle WA
St. Jude Donor '14
Melting Slicks
Joined: May 2007
Posts: 3,246
Likes: 4
From: Bay Area CA
Race Director
Joined: May 2005
Posts: 10,674
Likes: 122
From: Millington Illinois
St. Jude Donor '08-'09
For anyone deciding on full roller rockers buy a quality product IE Comp, Crower, Crane gold. Don't buy the cheap ebay sets. When they come apart they can wreak havoc on the internals.
Melting Slicks
Joined: May 2006
Posts: 3,438
Likes: 41
From: Raleigh NC
St. Jude Donor '13-'14
I've done this a number of times as part of a top. They will NOT fit underneath the stock stamped-steel or C3 cast covers. Options are tall covers - or if you're going for a "stealth" stock look spacers are available to allow use of the stock covers. I *love* a "sleeper" hot stroker
What about Comps 4600-16? Corvette Fever did an article on them. http://www.corvettefever.com/techart...r_rockers.html
They fit a full roller under stock LT1 valve covers by using these poly locks. Have you used/heard of these? Also, if you have, do you have to grind off the drippers? The way they mention it makes it a little unclear.
Peter
Last edited by LeMans Pete; Jul 16, 2009 at 11:14 PM.