I posted a question and now im confused. Why the hell would you want to mix rocker ratios? Can someone explain why? And what would be my best bet on this one?


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1987 T/A GTA 5.7L, Bored .020 and ported for .202 valves, edelbrock headers, flowmaster exhaust, JET STAGE II chip, Comp CAM, Adjustable fuel pressure, Airfoil, K&N filter, B&M stage 2 shift kit, and a home depot ram air(Hey it looks good and it works)

 

TPIS did some testing and found that mixing rocker ratios was better than one ratio. But the difference wasn't that much. I have the book but I don't feel like looking it up. Yes, you can use 1.6's on both intake and exhaust. This effectively increases the area under the curve on the cam allowing more flow due to being at a higher lift longer.

 

I cant explain why, but its ok to mix, I tested 1.6 on the intake and it felt better but the idle was not so good anymore, and then put on 1.6 on exhaust but then the idle was horrible so I stayed with 1.5 on both, I'll try to upgrade when my 383 is ready.....

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GTA -89:Free flow muffler,dual 3" HF cats, Edelbrock headers, Vette heads, 1.52 RR 7/16, ZZ-9 cam, Big Mouth, AS&M LTR, !plenum, 52 TB, MSD 6AL, TPIS level V prom, Superior shift-kit and all the minor mods, a Canfield headed 383 in the works!! ready May 2001...ok..june...july..and with Accel DFI....looking for SR or miniram....
http://www.itv.se/tacs/members_cars/m279/m279.html (Swedish Trans Am Club)

 

<----- Has 1.6 rockers on both Intake and Exhaust. Idles fine (adjusted target idle figures in EPROM).

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1987 GTA L98 MD8 GH3
355 '97 Vortec 4-bolt block, TRW(suck) forged pistons 10:1 CR, TFS 23*, LT4 Hot Cam, Ported plenum and intake, SLP Siam Runners, Edelbrock TES, gutted Cat, Flowmaster, K+N cone, AFPR, TB bypass, AirFoil, !AIR, !A/C, !EVAP, ARAP, 2300 stall, Hotchkis STB.

 

And make sure your pushrods have enough clearance (on 305)

test

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1985 IROC-Z
TPI 305, 700R4 with shift kit, richmond 3.73's, auburn pro series posi, crane compucam 2030, ported plenum, gutted air boxes, all the little insignificant stuff.

 

if you look at most of the info on a car that has different ratios it usually is an engine witth a dual plane intake reason being the dual intake has shorter runners for the 4 center cylinders most of the time they aren't the ones that need the extra lft so they put them on the longer runner cylinders another example is certainchevy heads don't have very good exhaust port flow(ideally it should be around 80% of the intake's flow)som some guys put the 1.6's on the exhaust only on a ltr design intake where the runners are equal go wih the same ratio

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87 trans am,gm crate 350(4 bolt mains 10to1),L98 aluminum heads,LT4 hot cam,slp runners,slp 1 5/8 headers,3in.y-pipe,edelbrock base,hi flo cat,air foil,afpr,as&m ported plenum,gutted airbox,t-5 tranny w/centerforce clutch and a 3.27 9bolt(11.9in. brakes),ed wright's fastchip,relocated iat sensor,160 fan switch,tb bypass,accel supercoil,cap& rotor,hollowed maf,slp 3in. catback,a/c delete.

shooting for 13's!!!!!!!

14.10@97mph w/2.01 60'(auto ET)

slp catback is finally on!!!
fastchip prom is in.OH!MAN!
FLOWMASTER S.U.C.K.S

 

Nine times out of ten the 1.6 is used on the exhaust only in order to make up for a single pattern cam and/or poorer (as compared to the intake side) flow characteristics of the exhaust side of most heads.

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"Question with boldness even the existence of a God; because, if there be one, he must more approve of the homage of reason, than that of blind-folded fear."

-Thomas Jefferson