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Big Block 1.5 vs 1.6 rockers #681779 04/27/10 12:31 PM 04/27/10 12:31 PM
Joined: Jan 2010 Posts: 456 Santa Barbara, CA HitIt OP mopar
HitIt OP mopar Joined: Jan 2010 Posts: 456 Santa Barbara, CA	Hello all, I�m considering upgrading from stock factory rockers on my 440 to a set of adjustables most likely from Crane. Since they come in 1.5 and 1.6 ratios I was hoping to hear what you think would be the best choice for my particular engine. Here are some specs- 100 miles on complete rebuild. TRW Flat top Pistons, 30 over. 10.5:1 compression. 906 heads with stock valves and ports. Elgin hydraulic cam with 241 duration, .484 lift, centerline is 108. Car has manual brakes. It is just driven for fun on the weekends. Thanks in advance for your opinions.

Re: Big Block 1.5 vs 1.6 rockers [Re: HitIt] #681780 04/27/10 12:40 PM 04/27/10 12:40 PM
Joined: Aug 2006 Posts: 1,884 Tracy CA R rabid scott "You're Where?"
rabid scott "You're Where?" R Joined: Aug 2006 Posts: 1,884 Tracy CA	I'd like to know too. I heard the factory stamped jobs were small ratios, something below a 1.5 ratio rocker.

Re: Big Block 1.5 vs 1.6 rockers [Re: HitIt] #681781 04/27/10 01:10 PM 04/27/10 01:10 PM
Joined: Oct 2005 Posts: 8,871 Ontario, Canada S Stanton Don't question me!
Stanton Don't question me! S Joined: Oct 2005 Posts: 8,871 Ontario, Canada	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.

Re: Big Block 1.5 vs 1.6 rockers [Re: Stanton] #681782 04/27/10 01:26 PM 04/27/10 01:26 PM
Joined: Jan 2010 Posts: 456 Santa Barbara, CA HitIt OP mopar
HitIt OP mopar Joined: Jan 2010 Posts: 456 Santa Barbara, CA	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.

Re: Big Block 1.5 vs 1.6 rockers [Re: HitIt] #681783 04/27/10 01:29 PM 04/27/10 01:29 PM
Joined: Mar 2008 Posts: 5,746 Ontario, Canada Dodgem master
Dodgem master Joined: Mar 2008 Posts: 5,746 Ontario, Canada	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.

Re: Big Block 1.5 vs 1.6 rockers [Re: Dodgem] #681784 04/27/10 01:55 PM 04/27/10 01:55 PM
Joined: Jan 2010 Posts: 456 Santa Barbara, CA HitIt OP mopar
HitIt OP mopar Joined: Jan 2010 Posts: 456 Santa Barbara, CA	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!

Re: Big Block 1.5 vs 1.6 rockers [Re: Dodgem] #681785 04/27/10 02:39 PM 04/27/10 02:39 PM
Joined: Oct 2005 Posts: 8,871 Ontario, Canada S Stanton Don't question me!
Stanton Don't question me! S Joined: Oct 2005 Posts: 8,871 Ontario, Canada	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.

Re: Big Block 1.5 vs 1.6 rockers [Re: Stanton] #681786 04/27/10 06:18 PM 04/27/10 06:18 PM
Joined: Apr 2008 Posts: 90 NL F Frederick member
Frederick member F Joined: Apr 2008 Posts: 90 NL	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.

Re: Big Block 1.5 vs 1.6 rockers [Re: Frederick] #681787 04/27/10 08:04 PM 04/27/10 08:04 PM
Joined: Oct 2005 Posts: 8,871 Ontario, Canada S Stanton Don't question me!
Stanton Don't question me! S Joined: Oct 2005 Posts: 8,871 Ontario, Canada	Well that's no arguement !!! "Duration" is ALWAYS measured and stated in DEGREES. Duration is always measured at the cam (to avoid any confusion due to rocker ratio !!!). 0.050"x1.067=0.053" I don't see degrees here, all I see is lift. Those who argue that duration changes are measuring lift at the valve. Of course it will change there, due to the different ratio the valve will have .050" of lift sooner and later in the cycle BUT the actual duration from the time the valve starts to open and finally closes WILL NOT CHANGE based on the different ratio of rocker. Regardless of ratio, the pushrod, rocker and valve only start to move when the lifter is put in motion by the cam. You will see more lift through the entire cycle but if the cam spec says it has 284 degrees (total) of duration, no rocker on the planet is gonna change that.

Re: Big Block 1.5 vs 1.6 rockers [Re: HitIt] #681788 04/27/10 11:05 PM 04/27/10 11:05 PM
Joined: Nov 2006 Posts: 1,457 oklahoma F forphorty pro stock
forphorty pro stock F Joined: Nov 2006 Posts: 1,457 oklahoma	I believe a switch to a 1.6 rocker often requires that you clearance the head a bit for the pushrod, especially if you are switching from a 5/16ths to a 3/8ths pushrod.

Re: Big Block 1.5 vs 1.6 rockers [Re: forphorty] #681789 04/27/10 11:22 PM 04/27/10 11:22 PM
Joined: Mar 2003 Posts: 1,710 Spokane Wa CrazyRocker70 top fuel
CrazyRocker70 top fuel Joined: Mar 2003 Posts: 1,710 Spokane Wa	how much lift can your run with a stock head? i thought i heard somewhere that you will hit the guides over .510 without having them machined down? am i way out there with this?

Re: Big Block 1.5 vs 1.6 rockers [Re: forphorty] #681790 04/27/10 11:32 PM 04/27/10 11:32 PM
Joined: Jan 2003 Posts: 931 D dulcich super stock
dulcich super stock D Joined: Jan 2003 Posts: 931	I'd say if you are going to buy them, get the 1.6:1. Another set of slow 1.5 rockers is a waste of money; might as well just use the stock ones. With your older cam design, the conservative ramp rates should have no problem with the faster rocker. Even the factory Magnum small blocks had 1.6:1 ratio, and really, 1.6 isn't much ratio either, compared to some engines like BBC or Cleveland, which are in the 1.7's stock. Duration at .050 is measured at the tappet (tappet rise spec .050-inches), so that specification is independent of rocker ratio. Although the duration will remain the same, it will act like a slightly bigger cam in terms of idle and vacuum because of the increased valve overlap area. Just make sure you have enough spring for coil bind clearance and have retainer to guide (or seal) clearance with the added lift. -dulcich

Re: Big Block 1.5 vs 1.6 rockers [Re: HitIt] #681791 04/28/10 12:33 AM 04/28/10 12:33 AM
Joined: Feb 2003 Posts: 21,318 Manitoba, Canada DaytonaTurbo Too Many Posts
DaytonaTurbo Too Many Posts Joined: Feb 2003 Posts: 21,318 Manitoba, Canada	For your application, it's a waste of money IMO. All that money spent to upgrade your lift from 484 to 516. Run a set of hd stamped rockers and be done with it. You can spend money on a new cam with a modern lobe rate like a comp xe-hl or a lunati voodoo and get more than 516 lift with a similar duration, and still not require adjustable rockers. With roller rockers and the issues they have(especially the cheapies), IMO it makes no sense to buy them for your combo. I know some guys are dead set on adjustables, but for your combo I think they're a terrible bang for your buck at this point.

Re: Big Block 1.5 vs 1.6 rockers [Re: DaytonaTurbo] #681792 04/28/10 12:10 PM 04/28/10 12:10 PM
Joined: Jan 2010 Posts: 456 Santa Barbara, CA HitIt OP mopar
HitIt OP mopar Joined: Jan 2010 Posts: 456 Santa Barbara, CA	Thanks all for the time and thoughts everyone. Aside from the side effect of getting a bit more lift with 1.6�s, again really all I am after is adjustability for preload since mine is not right. I am going to keep the stock setup for now, and see if I can dial in the preload a little better with some slightly longer pushrods. Thanks again Moparts crew, this is a great site. I�ve learned a lot and appreciate the help very much.

Re: Big Block 1.5 vs 1.6 rockers [Re: HitIt] #681793 04/28/10 12:28 PM 04/28/10 12:28 PM
Joined: Oct 2005 Posts: 8,871 Ontario, Canada S Stanton Don't question me!
Stanton Don't question me! S Joined: Oct 2005 Posts: 8,871 Ontario, Canada	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.

Re: Big Block 1.5 vs 1.6 rockers [Re: Stanton] #681794 04/28/10 12:48 PM 04/28/10 12:48 PM
Joined: Jan 2010 Posts: 456 Santa Barbara, CA HitIt OP mopar
HitIt OP mopar Joined: Jan 2010 Posts: 456 Santa Barbara, CA	Yep, I am surprised too. At the moment I�m waiting for a set of 9.400 pushrods to be delivered, as well as a pushrod length tool if these do not work. I have taken my pushrods out to measure them, they are the correct 9.315� size. Like I mentioned this is a bit of a mystery motor, I think that maybe the valve stems ends were refurbished and trued up, making them shorter?

Re: Big Block 1.5 vs 1.6 rockers [Re: HitIt] #681795 04/28/10 02:11 PM 04/28/10 02:11 PM
Joined: Oct 2005 Posts: 8,871 Ontario, Canada S Stanton Don't question me!
Stanton Don't question me! S Joined: Oct 2005 Posts: 8,871 Ontario, Canada	If you don't know what's in the motor then its possible they put new seats in the heads and that's the issue. They could have ground the ends of the valves but then they likely would have sunk them a bit doing a valve job on the original seats.

Re: Big Block 1.5 vs 1.6 rockers [Re: HitIt] #681796 04/28/10 05:43 PM 04/28/10 05:43 PM
Joined: Mar 2007 Posts: 9,336 South-Central (Sebring), FL Commando1 master
Commando1 master Joined: Mar 2007 Posts: 9,336 South-Central (Sebring), FL	Can somebody explain to me why you go to 1.6 rockers when you can just get a cam with a higher lift to begin with?

Re: Big Block 1.5 vs 1.6 rockers [Re: Commando1] #681797 04/28/10 05:59 PM 04/28/10 05:59 PM
Joined: Oct 2006 Posts: 3,054 USA B b54406barrel master
b54406barrel master B Joined: Oct 2006 Posts: 3,054 USA	I know it's not exactly what you asked but, I did minimal testing & it was long ago on the superflo on mopar stuff but getting more lift with a stock port 906 isn't going to do much, I don't think. They are pretty flat from about .460 or so up to .525 lift I checked them to, at least on the intake side. I wouldn't change 1.5 to 1.6 & expect much more horsepower.

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