1.6 rockers vs 1.52 rockers - pros and cons (Page 1/6)
RayOtton JAN 29, 11:25 AM
I'm about ready to add this mod but I'd like some input from the gurus as to which type I should go with.

Thanks.
dobey JAN 29, 01:20 PM
Pros: more lift == more air
Cons: more lift == less piston to valve clearance

If I was doing a performance 2.8/3.4 build, I think they'd be worth going with, as cam options are fairly limited.

The new Gen V V8s have 1.8 ratio rockers stock even.
RayOtton JAN 29, 01:58 PM
Is there a problem with valve clearance using the 1.6 rockers on a stock engine?

I read about excessive wear with the 1.6 rockers. Is that a fact or conjecture?
dobey JAN 29, 02:41 PM

quote
Originally posted by RayOtton:

Is there a problem with valve clearance using the 1.6 rockers on a stock engine?

I read about excessive wear with the 1.6 rockers. Is that a fact or conjecture?



It's a flat tappet system, so increased wear seems likely, yes. I don't know what the valve clearance is like on the stock engine. But increasing lift will result in decrease in whatever clearance there is. If you run at stock timing, it's probably not an issue. If the chain is stretched or you are installing the cam more advanced, it will likely become more relevant. I don't know the specs on the stock springs either, so they may be an issue as well. If you're just doing a throw n' go on a stock engine, you should be fine, but I'd check tolerances and springs just to be safe. Good time to replace valve seals and such too, since you're going to be in there.
lou_dias JAN 29, 04:04 PM

quote
Originally posted by RayOtton:
Is there a problem with valve clearance using the 1.6 rockers on a stock engine?
I read about excessive wear with the 1.6 rockers. Is that a fact or conjecture?


On the stock cam, you shouldn't have an issue. I think the stock springs support up to .450" lift...and you'd only be up to .437" on the exhaust which has more lift than the intake on the stock cam...

Spend the extra money on "full" roller rockers...also they'll be reusable if you decide to use a newer roller cam block for your next build... Summit has some aluminum ones - search for V6 narrow body aluminum roller rockers...
Patrick JAN 29, 04:53 PM

quote
Originally posted by RayOtton:

I read about excessive wear with the 1.6 rockers. Is that a fact or conjecture?




quote
Originally posted by dobey:

It's a flat tappet system, so increased wear seems likely, yes.



And for anyone who doesn't address the lack of zinc additive in modern engine oils, cam lobe/lifter wear could quickly become disastrous.

I've contemplated using 1.6 rockers in my Formula, but I'm concerned that the potential performance benefits would be minimal compared to potential excessive cam lobe/lifter wear.
Arns85GT JAN 29, 07:26 PM
I used 1.6 roller tips on my 2.8. The roller tips mean that there is no practical difference in wear. You get a lower exhaust note because the engine is breathing better. It is a cheaper way to increase your intake amount than a cam swap.

Arn
Patrick JAN 29, 08:16 PM

quote
Originally posted by Arns85GT:

I used 1.6 roller tips on my 2.8. The roller tips mean that there is no practical difference in wear.



Arn, the roller tips would help ensure that there wouldn't be any excessive wear on the end of the valve stems or on the tips of the rockers themselves, but how do the roller tips help minimize wear on the cam lobes and/or lifters? There's still going to be added force on those areas due to the extra leverage of the 1.6 rockers.
Spoon JAN 29, 09:36 PM
I put the 1.6 roller rockers on my 2.8 several years ago and I could tell a difference in get up & go. I also use the Rotella oil which still has the zinc in it AFAIK. You can still by the additive on the web.
I say go for it. Less work than swapping a cam.


Spoon

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"Kilgore Trout once wrote a short story which was a dialogue between two pieces of yeast. They were discussing the possible purposes of life as they ate sugar and suffocated in their own excrement. Because of their limited intelligence, they never came close to guessing that they were making champagne." - Kurt Vonnegut

Raydar JAN 29, 10:30 PM
I also ran 1.6 rockers on an otherwise stock cam. It was a 3.4 Camarobird engine, but the 2.8 uses a cam with identical numbers. I had no trouble at all.
There is no way that I would run a flat tappet engine without some sort of zinc additive or high zinc oil. I used to run Rotella T in my 3.4.

Having said all that... if you are into the engine anyway, and are replacing the cam, just get a cam with the lift numbers that you want, and use the 1.5 rockers. 1.6 rockers are, to me, a bandaid. They are an easy way to achieve more lift without going into the engine.
If you already have a high lift cam, and are adding 1.6 rockers, you need to pay attention to the total valve lift, and make sure that you are not going to bind the spring coils. That's a sure way to start breaking stuff.

I preferred the Comp Cam roller tip rockers. They are a good compromise between stock, and full roller rockers, without destroying your bank account.
They are available in 1.52 (which is actually stock spec) which I used with my 272 cam; and 1.6 ratios. I used the 1.52s because they are much more precise than the stamped steel stockers, and still had the roller tip.

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Raydar
88 Formula IMSA Fastback. 4.9, NVG T550

Praise the Lowered!