Re: Big Block 1.5 vs 1.6 rockers
[Re: Stanton]
#681782
04/27/10 01:26 PM
04/27/10 01:26 PM
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Joined: Jan 2010
Posts: 456 Santa Barbara, CA
HitIt
OP
mopar
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OP
mopar
Joined: Jan 2010
Posts: 456
Santa Barbara, CA
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Quote:
Personally I don't think that combination warrants the expense of roller rockers. What you have there is not much more than a stock rebuild. A quality stamped rocker or a nodular iron rocker would be a better and cheaper choice. This will also pretty much limit you to 1.5's. The 1.6 will increase lift but you should have thought of that when you bought the cam. Also, are the valve springs you have rated for the additional lift or are they pretty much at there limit for that cam? If its a performance gain you're after I can think of much better ways to spend that money.
It will no doubt illicit comments from the naysayers on here but higher ratio rockers are best suited when you're at the limits of your cam i.e. you have the biggest hydraulic made but want more valve lift out of it, you have the biggest solid made but want more valve lift out of it or you have the biggest cam that will fit in the hole and you want more out of it. Otherwise they're just a bandaid or diagnostic tool.
Good points, thanks. My main reason for this is adding the adjustibility. Just wondered if going to the 1.6 on my particualr setup would be good while I'm at it.
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Re: Big Block 1.5 vs 1.6 rockers
[Re: HitIt]
#681783
04/27/10 01:29 PM
04/27/10 01:29 PM
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Joined: Mar 2008
Posts: 5,746 Ontario, Canada
Dodgem
master
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master
Joined: Mar 2008
Posts: 5,746
Ontario, Canada
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I like the crane rockers if you can still get them. the 1.6 will give you .516 lift without changing the duration. There is always a gain in adjustable valve train not to mention the stamped are less than perfect 1.5. Do your pistons have valve notches. Although the lift change when the pistons are close is next to nothing at max lift the piston is 2 to 3" down the hole. Course you need push rods then too but can set your pre load to the bare minimum. (quicker higher reving)
and you will be able to adjust out that tick! LOL!
Last edited by Dodgem; 04/27/10 01:31 PM.
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Re: Big Block 1.5 vs 1.6 rockers
[Re: Dodgem]
#681784
04/27/10 01:55 PM
04/27/10 01:55 PM
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Joined: Jan 2010
Posts: 456 Santa Barbara, CA
HitIt
OP
mopar
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OP
mopar
Joined: Jan 2010
Posts: 456
Santa Barbara, CA
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Quote:
and you will be able to adjust out that tick! LOL!
Exactly. I have some longer pushrods on the way and will try that first. If I can't solve it that way I'm goigng to go to an adjustable setup. Thanks for your help on the other post as well Dodgem.
As far as the value for this engine I'm not that worried since this won't be my last mopar big block and will take a lot of the nice parts along to my next build.
Thanks agian for the opinions guys. Go Moparts!
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Re: Big Block 1.5 vs 1.6 rockers
[Re: Dodgem]
#681785
04/27/10 02:39 PM
04/27/10 02:39 PM
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Joined: Oct 2005
Posts: 9,031 Ontario, Canada
Stanton
Don't question me!
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Don't question me!
Joined: Oct 2005
Posts: 9,031
Ontario, Canada
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Quote:
without changing the duration
I've always believed that too. However, there are some on here who will argue that till they're blue in the face.
I still don't think the gains or advantages are worth the expense. It's a hydraulic cam - you can adjust the preload but then what, you'll never need to touch it again! How far off can it be ... factory decks and heads were never accurate! If the motor runs well, leave it alone - it's not a killer!
If you go with the new rockers you'll need pushrods. You should also change the shafts AND will have to fart around with spacers (aluminum rockers don't like getting cozy with cast iron pedestals or the stock hold-downs).
The money'd be better spent on a set of free-flowing mufflers.
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Re: Big Block 1.5 vs 1.6 rockers
[Re: Stanton]
#681786
04/27/10 06:18 PM
04/27/10 06:18 PM
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Joined: Apr 2008
Posts: 90 NL
Frederick
member
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member
Joined: Apr 2008
Posts: 90
NL
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1.6 vs 1.5 rocker will not change the seat duration, but will change the duration at 0.050" (and the duration at every other lift point)
Lift increase with 1.6 vs 1.5 = (1.6/1.5)= 1.067
So if you've got a camshaft with 0.484"lift on a 1.5 rocker, it will become 0.484x1.067=0.516" lift with the 1.6 rocker
Seat duration = 0.000" lift Not even a 1.9 rocker will change that. 0.000x1.9 is still zero.
If you look at the duration at 0.050" that does change with the 1.6 rocker, cause the 1.6 rocker increases lift. 0.050"x1.067=0.053" So what the duration the cam had at 0.050"becomes the duration at 0.053" with a 1.6 rocker. And the duration at 0.046875" becomes the duration at 0.050" (0.046875x1.067=0.050)
F.
383B, 9.8:1, Lunati 60302(220/226@0.050 262/268Dur, 0.475"/0.494", Stealth heads, Performer manifold, QF SS-750-AN carb, 3.31Diff, A833 4-speed manual.
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Re: Big Block 1.5 vs 1.6 rockers
[Re: HitIt]
#681793
04/28/10 12:28 PM
04/28/10 12:28 PM
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Joined: Oct 2005
Posts: 9,031 Ontario, Canada
Stanton
Don't question me!
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Don't question me!
Joined: Oct 2005
Posts: 9,031
Ontario, Canada
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Quote:
see if I can dial in the preload a little better with some slightly longer pushrods
Now this is a shock to me. I would have thought that after a rebuild the issue would have been too much preload due to decking the block and heads.
Tell us where you're at right now. What do you think the prelaod is or the valve lash.
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