True rollers or roller tip?
Thread Starter
Melting Slicks
Joined: Mar 2005
Posts: 2,350
Likes: 228
From: Northeast FL
True rollers or roller tip?
A little back ground before the questions....I have a 94 six speed that I use for auto x and a weekend driver. I have EM long tube headers, Random Tech cats and a Corsa system on order. Cut lid, K & N and Big Mouth Air Dam are already on.
I don't want to go all the way into the engine yet. That's next years' project. Is it worth pulling the valve covers and changing to the 1.6 rockers to get a little more lift out of the stock cam? Does the ECM need to be reflashed for that? Which are a better bang for the buck, the true roller rockers or just the roller tipped rockers? There's a fair amount of price difference between the two. And which will fit under the stock valve covers? Should I just wait until I pull the engine to bother with the rockers?
I don't beat the crap out of it but it is driven kind of (
) hard at the track. The rebuild will be fairly mild when I do it next year to stay legal in NCCC Group II. So this won't be any 600+ HP monster. Probably end up around 350 - 400 at most.
I don't want to go all the way into the engine yet. That's next years' project. Is it worth pulling the valve covers and changing to the 1.6 rockers to get a little more lift out of the stock cam? Does the ECM need to be reflashed for that? Which are a better bang for the buck, the true roller rockers or just the roller tipped rockers? There's a fair amount of price difference between the two. And which will fit under the stock valve covers? Should I just wait until I pull the engine to bother with the rockers?
I don't beat the crap out of it but it is driven kind of (
) hard at the track. The rebuild will be fairly mild when I do it next year to stay legal in NCCC Group II. So this won't be any 600+ HP monster. Probably end up around 350 - 400 at most.
Team Owner
Joined: Dec 2000
Posts: 90,675
Likes: 304
From: SE NY
Cruise-In II Veteran
Install a set of Comp Cams ProMagnum full RRs along with new valve springs for maximum benefit.
To minimize deflection also install 7/16" rocker studs, hardened guide plates and pushrods.
To minimize deflection also install 7/16" rocker studs, hardened guide plates and pushrods.
Thread Starter
Melting Slicks
Joined: Mar 2005
Posts: 2,350
Likes: 228
From: Northeast FL
Can't do either I just found out. NCCC won't allow internal mods to Group II cars. Even when I rebuild it the cam lift and duration has to be stock. So I can't play with the ratio on the rockers. Oh well. 
Race Director
Joined: Nov 2002
Posts: 19,149
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From: First to Sign Grumpy's Hat Only 53 miles from Hell
St. Jude Donor '06-'09-'10-'11
Originally Posted by JJ 86
Not to hyjack the thread but is 96 the only year gm put rr's on vettes?
Burning Brakes
Joined: Jun 2003
Posts: 937
Likes: 0
From: Bedford Tx
Originally Posted by tpi 421 vette
Most of the friction is in the fulcrum. Full roller rockers are the way to go.How much friction, is there, at the fulcrum of
a standard rocker in the SBC?
Or, better, how much energy is lost in
the fulcrum over one cycle?
I sorta don't believe the typical seat o' pants - dyno
or oil temp comments.
Last edited by silver84; Jul 7, 2005 at 10:52 AM.
Le Mans Master
Joined: Dec 2002
Posts: 5,270
Likes: 3
From: Seattle Area WA
Originally Posted by jwt1603
Can't do either I just found out. NCCC won't allow internal mods to Group II cars. Even when I rebuild it the cam lift and duration has to be stock. So I can't play with the ratio on the rockers. Oh well.
I have heard GM's ratios stock can range all over the board!
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Thread Starter
Melting Slicks
Joined: Mar 2005
Posts: 2,350
Likes: 228
From: Northeast FL
Originally Posted by USAsOnlyWay
Could you at least buy a quality OEM style rocker with the same ratio.
I have heard GM's ratios stock can range all over the board!
I have heard GM's ratios stock can range all over the board!
Race Director
Joined: Feb 2004
Posts: 12,517
Likes: 19
Originally Posted by silver84
Please enlighten me.
How much friction, is there, at the fulcrum of
a standard rocker in the SBC?
Or, better, how much energy is lost in
the fulcrum over one cycle?
I sorta don't believe the typical seat o' pants - dyno
or oil temp comments.
How much friction, is there, at the fulcrum of
a standard rocker in the SBC?
Or, better, how much energy is lost in
the fulcrum over one cycle?
I sorta don't believe the typical seat o' pants - dyno
or oil temp comments.
Melting Slicks
Joined: Mar 2002
Posts: 3,108
Likes: 126
From: S.L.C. UT
Originally Posted by silver84
Please enlighten me.
How much friction, is there, at the fulcrum of
a standard rocker in the SBC?
Or, better, how much energy is lost in
the fulcrum over one cycle?
I sorta don't believe the typical seat o' pants - dyno
or oil temp comments.
How much friction, is there, at the fulcrum of
a standard rocker in the SBC?
Or, better, how much energy is lost in
the fulcrum over one cycle?
I sorta don't believe the typical seat o' pants - dyno
or oil temp comments.
Last edited by tpi 421 vette; Jul 8, 2005 at 12:10 PM.
Burning Brakes
Joined: Jun 2003
Posts: 937
Likes: 0
From: Bedford Tx
Originally Posted by tpi 421 vette
What, you don't beleive full roller rockers improve performance?? It has been documented in about every magazine out there. Stock rockers don't hold up to high lift cams with high spring pressures real well either. I have seen plenty of stock rockers with the bottoms blown out. I wouldn't consider stock rockers in any sort of real performance engine build up, except for a very mild low budget engine.
Normal spring pressure, cam lift,
oiled-steel-on-steel coefficient of friction, etc.
I just don't believe that rocker-fulcrum
friction is significant, compared to
piston ring friction.
Drifting
Joined: Mar 2005
Posts: 1,923
Likes: 0
From: GA
Originally Posted by silver84
Please enlighten me.
How much friction, is there, at the fulcrum of
a standard rocker in the SBC?
Or, better, how much energy is lost in
the fulcrum over one cycle?
How much friction, is there, at the fulcrum of
a standard rocker in the SBC?
Or, better, how much energy is lost in
the fulcrum over one cycle?
