Blade

My next mod is 1.6 full roller rockers. My concern is... are my valves gonna hit the pistons ? Please tell me what you think. Right now I have stock heads, with LT4 springs, stock valves and the cam in my signature. Also... how do you calculate the lift when you have 1.6 rockers vs 1.5 rockers ? Thanx

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92 Z28 5.7
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Ported stock heads, XR270HR-10 cam, TES headers
Crane AFPR, Flowmaster catback, MSD ignition
#24 SVO injectors, 1LE aluminum driveshaft.

Best ET 13.3@107 mph

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RB83L69

You should have no interference problems. I'm running its big brother XR282HR with 1.6 rockers, no problems.

To figure out the lift, divide the spec for 1.5 rockers by 1.5, then multiply that result by 1.6.

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"So many Mustangs, so little time..."
ICON Motorsports

The ODB

I second the above post

93ND500

If you have the base lift info just multiply by the rocker ratio.
ie .280 at lobe = .420 at the valve with 1.5's and .448 with 1.6's
If you know the lift at the valve, just divide by what ratio rockers you have to get the base lift.

Looks like we were all typing at the same time on this one!!

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1993 C1500 Indy 500 Edition
1992 TA TPI setup
Stock motor, new one being built now.
www.geocities.com/wsleigh

[This message has been edited by 93ND500 (edited February 15, 2001).]

[This message has been edited by 93ND500 (edited February 15, 2001).]

Dan87IROC-Z

You have to have somewhere around the .600" to .650" lift areas before the valves will come close to the pistons on a 3.48" stroke motor.

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1987 Chevy Camaro IROC-Z
L98 TPI 350 (5.7L)
TH 700R-4 Transmission
Borg Warner 7.75" 9 Bolt Rear End

Current Mods: LT4 Hot Cam, Comp Cams 1.52:1 Roller Rocker Arms, Edelbrock TES 1 5/8" Headers, Hooker 3" Aerochamber Cat-Back System, Performance Resource Chip, 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 (w/o LT4 cam): 14.32 @ 97.7mph
(corrected for elevation)

7.5" 10 Bolt with 3.42s soon to come!

Blade

Yeah I remeber something about the total lift being around .600 before there was danger of valves hitting the pistons but I wanted to make sure just in case Looks like I'm gonna be ordering the cheaper Proform ones. If they right when they say 15-20 HP... combined with some of my latest mods... 12s here I come! hehe

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92 Z28 5.7
------------------
Ported stock heads, XR270HR-10 cam, TES headers
Crane AFPR, Flowmaster catback, MSD ignition
#24 SVO injectors, 1LE aluminum driveshaft.

Best ET 13.3@107 mph

Click here to see my car at Truspeed.org
Check out Truspeed
Check out the Bin Archive

JoelOl75

Your mod is no problem. But to mention that most piston to valve interference is caused more by duration than by lift. Just think on a low duration cam what position the valves are more likely to be in regardless of lift? Closed pretty much. Duration/Overlap/Seat timing is the biggest prob where small lifts can smack a piston.

Beefy89

If you go over .500" lift you better check the clearance just to be safe.

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We need Perry Mason

ede

i always check the pistom to valve clearance and i've never seen anything close to a problem untill about .650 lift. i just checked it on a 355 w/.550 lift and the thick wad of play dough i used wasn't even dented by the valves, must of been .2 to .25 thick.

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ICON Motorsports

1st & 3rd

CamaroZ_85

dont know if you're aware but you'll probably have more problems fitting the rockers under the valve covers than anything, you may have to cut the webbing out of them but if thats your biggest obstacle go for it

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350, Comp 262, Edelbrock Performer intake 600 cfm carb and exhaust, headers
-JVC, Eclipse, Pioneer, MTX, Phoenix Gold, Planet Audio