1.6 rockers

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Feb 18, 2010 | 10:35 AM

1986-z51

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Instructor

Joined: Sep 2009

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From: seabrook tx

1.6 rockers

Here is what i found out about swaping from 1.5 to 1.6 rockers.Got this info from comp cams web site.
1986 w/aluminum heads

stock intake lift. 403 add 1.6 rockers-428

Exaust 415 add 1.6 rockers-441 Not to bad for a bolt on.Although not sure if its worth 20 hp.

Feb 18, 2010 | 08:06 PM

RetiredSFC 97

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From: Somewhere in Mo

St. Jude Donor '09-'10, '14

What's the price for 20 HP gain?

Feb 18, 2010 | 08:11 PM

JackDidley

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From: Database Error Indiana

Quote:

Originally Posted by 1986-z51

Its worth doing. First mod I did when I had my 86.

Feb 18, 2010 | 08:20 PM

John A. Marker

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From: Dublin CA

Your gain will be more like 5-10 HP in real life. But there are additional advantages that are not listed. If you are running the stock stamped rockers, you will notice that the oil temp will drop about 5-10 degrees by going to roller rockers. You can run the engine with the valve cover off and not have the oil squirt a foot beyond the engine. Warning....it will still fill up the lip at the bottom of the head and leak onto the exhaust manifold.

Feb 19, 2010 | 12:16 AM

dogfish246

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From: North New Jersey

Im tempted to do a 1.6 RR job on my 96 but I dont know if I have the mechanical know how... I can do a lot (water pump, opti, fuel pump, etc) but if you mess these up, the engine can be destroyed!

Are there any negatives?

Feb 19, 2010 | 12:26 AM

cv67

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From: altered state

St. Jude Donor '05

If you tackled a water pump then you can do rockers, too, just follow instruction and take your time.

Feb 19, 2010 | 12:36 AM

dogfish246

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From: North New Jersey

Quote:

Originally Posted by cuisinartvette

If you tackled a water pump then you can do rockers, too, just follow instruction and take your time.

But dont you have to worry about geometry and torquing them properly so that the metal tester piece can move in and out between the rocker and the lifter like a knife moves in and out of butter? I thought there was a lot to it?

IDK, I was watching videos on youtube to see whats involved and it seems like a lot... I would love to get some 1.6RRs and do the job myself, but I really dont want to mess up my engine. (its my dd to and from college)

Anyone know of a good writeup with lots of pics and directions?

Last edited by dogfish246; Feb 19, 2010 at 12:40 AM.

Feb 19, 2010 | 02:36 AM

65Z01

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From: SE NY

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The a few main issues going with higher ratio RRs are:
-assure the roller crosses the valve stem tip equally on either end of travel. Install one with stock pushrods and measure travel; if adjustment needed use an adjustable pushrod & test spring to determine correct pushrod length.
-valve lash adjustment: While I twirl the valve step, the zero lash adjustment from just beginning to feel drag to unable to spin the valve is ~1/4 turn. So I adjust to zero lash then go 1/2 turn more plus 1/8 tuurn. This sets load to 1/2-3/4 turn beyone zero lash.
-what new valve springs, if any, should be used with the new RRs. I looked for a similar lift cam, then used their recommended spring.

I installed 1.6:1 ProMagnum RRs for 7/16" studs with CC 981 springs on my '88 L-98 about 8yrs ago and they are still quiet.

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Feb 19, 2010 | 08:54 AM

coupeguy2001

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From: Phoenix AZ

2021 C4 of the Year - Modified Finalist

I prefer to do a running valve adjustment, but that is just me. This way, i can see and hear if there are any problems prior to installing the rocker cover. But....it's a lot of extra work.
In addition, you do not need a feeler gauge (tester metal piece) fr hydraulic lifter engines.
That step is just for solid lifters, and if you have a factory cam, you wouldn't have those.

Feb 19, 2010 | 09:29 AM

#10

dogfish246

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From: North New Jersey

Quote:

Originally Posted by 65Z01

So if its self aligning do you have to worry?

Quote:

Originally Posted by 65Z01

-valve lash adjustment: While I twirl the valve step, the zero lash adjustment from just beginning to feel drag to unable to spin the valve is ~1/4 turn. So I adjust to zero lash then go 1/2 turn more plus 1/8 tuurn. This sets load to 1/2-3/4 turn beyone zero lash.

So since I have the stock LT1 I wouldnt have to use the feeler gauge, just set the lash 1/2 a turn??

Quote:

Originally Posted by 65Z01

-what new valve springs, if any, should be used with the new RRs. I looked for a similar lift cam, then used their recommended spring.

I heard that the LT4 springs or the equivalent beehive springs will be what I would need. But then how do you install springs? I know they are not just drop in...

Quote:

Originally Posted by 65Z01

I installed 1.6:1 ProMagnum RRs for 7/16" studs with CC 981 springs on my '88 L-98 about 8yrs ago and they are still quiet.

So will they last like the stock rockers? Will they fit the stock valve covers? Do they have any negatives?

After install, would a tune be necessary or just something that would make the install "better"? And what kind of tune (dyno, chip, etc)

Thanks, I have like 1*10^10000 questions!

Feb 19, 2010 | 04:43 PM

#11

jaa1992

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From: Life is just one big track event. Everything before and after is prep and warm-up and cool-down laps

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St. Jude Donor '12

I did 1.6 roller tips on my LT1. At the same time I had the heads off for a freshening so I just dropped off the heads, springs and keepers and had the machine shop put them on when they did the valve job. It was about $200. When I put the heads on I used the procedure in the FSM to set the lash. When I started it I had a little rubbing on the drip tabs of the valve covers, used a dremel to score them and snapped them off. No noise even at 6000 rpm.

Feb 19, 2010 | 06:35 PM

#12

65Z01

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From: SE NY

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Quote:

So if its self aligning do you have to worry?

There is no worry unless your engine has non-hardened guide plates like the 113 heads on the L98.

Quote:

So since I have the stock LT1 I wouldnt have to use the feeler gauge, just set the lash 1/2 a turn??

No feeler gauge is needed. I twirl the pushrod between thumb & finger while I tighten the rocker nut.

Quote:

But then how do you install springs?

To install springs you need to keep the valve from dropping into the cylinder. I had no compressed air so manually turned the crankshaft till the piston was nearly at TDC, fed in a length of nylon rope, turned the crank till the rope was pressed against the valves. Then I removed the keepers, retainers and springs. Once the new springs etc were installed, I turned the crankshaft back a bit and removed the rope from the sparkplug hole. I then repeated the procedure to install new springs on each valve for each cylinder.

Quote:

So will they last like the stock rockers? Will they fit the stock valve covers? Do they have any negatives?

So far they are performing well.
I had to machine down the drip tabs and narrow the bolt bosses to clear the ProMagnum RRs.

Quote:

After install, would a tune be necessary or just something that would make the install "better"?

For "tuning" I use an AFPR but no adjustment was required with the new RRs.
For minor air flow changes an AFPR works well to adjust fuel flow to match; for major air flow changes a modified chip would be best.

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