1.6 roller rockers

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Jul 27, 2006 | 01:58 PM

flatbush862

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From: Centerport NY

1.6 roller rockers

Another fundamental question - on the 1.6 roller rockers -

- other than reducing friction loss from the rollers - what is the advantage of a 1.6 ratio over stock?

- Can these be installed on otherwise stock engines?

- When installing - the engine cyliner has to be at top dead center i.e. both valves closed?

- any good links on the "how to do" for the installation?

Thanks again - you guys have been a wealth of information

Flatbush862

Jul 27, 2006 | 02:12 PM

silver86

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From: Woodstock Georgia

I would say the friction reduction is a secondary benefit, and increased lift is the primary benefit. For example: a cam and 1.5 ratio combination yields .400" lift, with the 1.6 ratio rocker, the lift is increased to .427".

The cylinder must be at its top position when installing to relieve any load from the cam lobes allowing a proper installation.

They can be installed on a stock engine.

Jul 27, 2006 | 02:33 PM

flatbush862

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From: Centerport NY

Thanks Silver - so during installation of the rockers you need to manually rotate the engine -basically by removing the spark plugs to relieve compression and turn the crank with a wrench to get the cylinder up?

Jul 27, 2006 | 02:36 PM

ALLT4

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From: Howard PA

Actually a 1.6 rocker will place more load on the lifter than a 1.5 because of the geometry. There is the benefit of added lift over a 1.5 and being able to use a cam with smaller lobes so to speak. So a the benefits of a 1.6 far outweigh any detriments.

I think you wind up with more spring clearance also as the fulcrum point is moved back towards the pushrod. This also screws up pushrod length though, usually not enough to worry about but checking tip to valve tip centering wouldn't hurt.

My feelings are that unless you reach really radical lift numbers 1.6 rockers aren't necessary. The same lift can be achieved with a cam cam change with added duration.

In the original posters case since you already have 1.5's moving to 1.6 rockers will add lift but hardly any duration.

Jul 27, 2006 | 02:52 PM

CFI-EFI

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From: The Top of Utah

Quote:

Originally Posted by flatbush862

1.) - other than reducing friction loss from the rollers - what is the advantage of a 1.6 ratio over stock?

2.) - Can these be installed on otherwise stock engines?

3.) - When installing - the engine cyliner has to be at top dead center i.e. both valves closed?

4.) - any good links on the "how to do" for the installation?

1.) The cam lobe lift multiplied by the rocker arm ratio, equals the valve lift. A greater rocker ratio makes for a great valve lift.

2.) Yes.

3.) No. All you have to do is loosen the nut to remove the old rocker. After they are on the engine, you will have to have each lifter, in turn, on the base circle of the cam in order to find "zero lash" and then add your preload from there.

4.) The FSM would be a good start. There are dozens of threads on here, concerning the adjustments after they are on the engine.

RACE ON!!!

Jul 27, 2006 | 02:53 PM

silver86

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From: Woodstock Georgia

Quote:

Originally Posted by flatbush862

Correct. Bring the number one piston to TDC, remove the old and install the new rockers, then rotate the crank 45 degrees and move to the next piston in the firing order, not the one physically next to the cylinder just changed.

Jul 27, 2006 | 03:54 PM

Atok

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From: NS

Quote:

Originally Posted by silver86

I agree with what everyone here has said, but you always should change your valve springs when you install 1.6 rockers. Or at least check the coil bind on the ones you currently have. Either way you need to remove the spring. So you need to fill the cylinder with compressed air via the spark plug hole to hold the valves closed to remove the spring(s).

When I replaced my rockers I measured the coil bind on my stock LT-1 springs and stock cam. Although they would work with 1.6 rockers, the clearance was far too tight, very close to binding. The new LT-4 springs I bought were fine for 1.6 rockers and stock LT-1 cam - they measured safe up to the lift of a LT-4 HOT cam. Anything bigger and you'll need different springs.

Jul 27, 2006 | 09:47 PM

Nathan Plemons

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Quote:

Originally Posted by ALLT4

My feelings are that unless you reach really radical lift numbers 1.6 rockers aren't necessary. The same lift can be achieved with a cam cam change with added duration.

But you can't change the cam without taking a whole lot more of the engine apart. Also it is NOT always desireable to increase duration, in fact obtaining a higher lift while maintaining the same duration is an excellent way to gain more power without the penalties associated with changing the other cam specs.