I currently have an 87 LB9 IROC with 700-R4. I'm wondering if it would be worth my while upgrading to 1.6 rockers? What sort of gain would I get from them?

Also, any reason why I can't use something like 1.9??

Rob

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1987 IROC-Z Auto (LB9)
Black/grey with kick *** looks

Mods
Custom exhaust. 4 Inch pipe from the headders all the way back to a single muffler at the rear. No Cat.

Future mods:
K&Ns
RAM Air
New Underdrive pulleys-either March performance pulleys or Auto Specialties Performance

 

Yes you will benefit from 1.6 roller rockers. Typically you'll see 5-10 HP from them in a stock car, and 10-15 HP if you have other mods like intake and exhaust.

You cant use 1.9 ratio because your springs wont take that kind of lift.

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1991 Camaro Z28
5.7L 5-Speed (originally 305)
13.25 @ 107.18 MPH
Southern California
Member: SoCal 3rd Gen F-Bodies
Webmaster: SoCal F-Bodies
-=ICON Motorsports=-

 

you would benefit, but is it worth 250$ for self aligning roller rocker arms for only 10 hp?????

 

The money it costs to buy a new set of rocker arms is more wisely spent on a new cam, go with that, you'll get a lot more for the money.

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1987 Chevy Camaro IROC-Z
L98 TPI 350 (5.7L)
TH 700R-4 Transmission with 2.77:1 Rear End

Current Mods: Edelbrock TES 1 5/8" Headers, Hooker 3" Aerochamber Cat-Back System, Performance Resource Chip with 160* Thermostat, Accel Ignition Coil, Cap, Rotor, 8.8mm Wires, K&N Filters, JET TPI Air Foil, All Free Mods, Falken ZIEX Z-Rated Tires.

Best ET : 14.32 @ 97.7mph
(corrected for elevation)

Soon to come: LT4 HOT Cam, Air Flow Research 190cc Heads, 2800 RPM Stall Converter and SLP 3.70 Rear End Gears.

 

250$ for 10 horse is good how much did you pay for a catback that gave you less than that? A cam isn't going to be cost effective unless you do it yourself probobly 400$ in labor plus 250 for the cam. Thats 650 bucks for 20 mabey 30 horse. Rockers are good cheap easy to do horsepower.

 

i was going to do that mod but was the discouraged when i found out by pulling a valecover, you have to pull the heads and make the slots in the heads wider because the pushrod's angle is gonna change and its gonna rub the head alot. i think 87 still uses guideplates though88 is the first for self alighning rockers i believe.

-Stell

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1988 IROC 305TPI MINT!!
Mods= Accell SuperCoil, MSD 6A, Ported Plenum, No MAF Screans , K & N, 160 Thermostat+ Temp Switch, Relocated MAT, Cold Air

 

Ah, I thought they would just bolt in without any modifications to the heads. Does anyone know for sure that the heads will need modified?

I would get a cam change but the lobor cost is putting me off. Anyone know anything else except whats in my sig tht I could do??

Thanks again

Rob

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1987 IROC-Z Auto (LB9)
Black/grey with the stance of a streetfighter

Mods
Custom exhaust. 4 Inch pipe from the headders all the way back to a single muffler at the rear. No Cat.

Future mods:
K&Ns
RAM Air
New Underdrive pulleys-either March performance pulleys or Auto Specialties Performance
Air foil

 

There is enough part-to-part variablilty on factory production heads that you really won't know if you "need" to machine the heads until you try. However, if you do the pushrod hole slotting (which is what you're doing in this machining process) up front, you know there won't be any problem. The reason for all this is that you are shortening the distance between the pushrod to rocker folcrum to increase the ratio, and pushrods typically already ride pretty close to the inside edge of the slot. As for 1.9's, that wouldn't work because the total length between the rocker folcrum and valve is too short. Big block Chevys use 1.7's stock, by the way, and can do this because of the longer distance between those two features.

Someone said on another post that you don't get much benefit from 1.6's with a mild cam. I'd have to second that motion, having put 1.6's on a 350 I used to have in the '57. They made absolutely no difference in my 1/4 times.

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82 Berlinetta, orig V-6 car, now w/86 LG4/TH700R. 2.73 unlimited slip. Cat-back from '91 GTA, Accel HEI SuperCoil. AMSOIL syn lubes bumper-to-bumper. Daily driver, work-in-progress (LB9 w/ZZ3 cam, TBD heads, exhaust, paint, etc.).
57 Bel Air, my 1st car. 0.030 over 396, Weiand Action+, Edelbrock 1901 Q-Jet, Jacobs Omnipack, 1-3/4" headers, TH400 w/TCI Sat Night Special conv & shift kit, 3.08 10-bolt, AMSOIL syn lubes bumper-to-bumper. Best 15.1 @ 5800' Bandimere. Daily driver while Camaro was being put together.

 

RMK,

I did some research before installing 1.6s on my '86 LB9/TH700-R4. With only 45K miles I couldn't justify changing my camshaft, so I used a program to plot my valve curves with both the stock 1.5:1 ratio rocker arms, and with 1.6:1 ratio rocker arms. After checking spring pressures at various heights, I installed 1.6:1 roller-tip rockers. I was able to use the stock springs, pushrods, valve rotators, and had plenty of lifter pintle adjustment. There was no binding at either end of the travel nor under the rocker at the valve spring retainers. The factory "LA" cam is so lame, it will allow the extra lift without even getting close to binding or stressing the springs beyond design tolerances.

My calculations of valve lift and timing changes indicated a 16.6 HP increase, and a 17.4 lb/ft torque increase. Realistic gains are probably more like 10-12 HP peak. What was more significant was the plots showed more open area at an earlier point in the rotation, providing more area under the curve at the correct points of piston travel. It seems that despite the weenie little gross lifts of the cam, the GM powerplant boys at least got the profile and timing about right. The torque at lower RPM is the real benefit, and I notice more torque at a lower RPM, around 3000. Crane advertises a 15-20HP gain with 1.6:1s, but that is probably pretty optomistic and under ideal conditions.

If you decide to do the same, you should check the cam lift with a dial indicator first. My "LA" cam actually had an indicated lift of about .003" MORE than the factory specs, so I felt pretty lucky to have the "Peanut HOT" cam. (LOL!) If you have any appreciable wear, you are probably wasting money on rockers. You should also check the valve springs closely for cracks and test for closing pressure.

I used Crane 11807-16 roller tip rockers. The set of 16 came with nuts and *****. The roller tip may extend the life of your valves as well, not putting as much side stress on them. The set cost me $114.00 through Performance Automotive Warehouse. Since your rockers should be self-aligning, they'll cost a few dollars more. The friction reduction from the roller tips alone should help offset the additional power required to open the valves to higher lifts and free up some power.

If a ten horsepower increase is worth $120.00 and some free time to you, then it probably isn't a waste.

As far as 1.9:1 ratio rockers, the highest I've ever seen were 1.72:1 and they are for Pontiac engines, not Chevys. The lame little 305/auto cam would probably allow it, though, and I've always wondered about trying a couple of Poncho rockers on the little engine just to see how they cleared. That would be the really-cheap guy's cam swap.

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Later,
Vader
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"No matter how hard you try you can't stop us now"
Adobe Acrobat Reader 4.0

 

It looks a little like this:



------------------
Later,
Vader
------------------
"No matter how hard you try you can't stop us now"
Adobe Acrobat Reader 4.0

 

LOL
A peanut hot cam ...
Oh that was gold
yea I think I have one of those too!
seriously though I think I might invest in some 1.6 RR if only I can find cheaper Self aligning ones than crane sells (300$ for 15hp = not worth the hassle)


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88 WS6 T/A 305 TPI--
K&N,Air foil,hypertech chip, thermostat+fanswitch
free mods, dynomax exh, urethane motor+trans mounts,
SSM frame con, Bilsteins
very trick homemade ramair.

 

Vader

So the 1.6 rockers should work fine with the standard cam without needing head modification? But what if I then decide to go for a cam later on, will the extra lift be too much?

Maybe I should just take the easy route and buy a vortech supercharger.

Rmk

------------------
1987 IROC-Z Auto (LB9)
Black/grey with the stance of a streetfighter

Mods
Custom exhaust. 4 Inch pipe from the headders all the way back to a single muffler at the rear. No Cat.

Future mods:
K&Ns
RAM Air
New Underdrive pulleys-either March performance pulleys or Auto Specialties Performance
Air foil