I am thinking of upgrading my stock valvetrain to 1.6 rockers. My questions are first, can the cam take the extra lift? Will I need to change the length of the pushrod? Is there anything special I also need to add to say use a set of roller rockers? And what kind of performance increase might I see given the profile below? Thanks.

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87 GTA 350 L98
K&N filters, beefed up TH-700r4, Accel Manifold, Ported Plenum and Runners, Fuel Press. Regulator 49.5psi, air foil, modified MAF, SLP cold air box, Hypertech Thermomaster chip w/160 thermostat, MSD 6AL and Blaster 3, B&M shift kit & megashifter, Moser Ford 9in Rear with Richmond 3.50 and locker, Edlebrock TES headers and Cat Back,Hotchkis setup in rear, Poly suspension and Koni in the front, relocated MAT, bypassed IAC, 300 lbs lighter

Fastest ET's
Stock-0-60 6.8, 1/4 15.0 @ 94
Best-0-60 4.7, 1/4 12.8 @ 112
Norm-0-60 5.2, 1/4 13.2 @ 108

 

The cam does not care. The push rods do not care. The valve springs, however, most definitely do care, because they will be getting stressed considerably more. Those are what I would be worried about the most. You'll be going from an actual ratio of somewhere around 1.4 (stock rockers are NEVER 1.5 no matter what the book says, plus there's all their flexing that reduces the valve lift even further) to 1.6 actual, which is a big step for the springs. Get new ones such as Comp 981s at the same time.

I'd expect to see somewhere around 8 to 10 HP gain from the rocker upgrade with the stock cam and good new springs. The motor will almost certainly run smoother too. Like I mentioned, you'd be amazed at how pathetic stamped sheet metal rocker arms really are.

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

 

I installed crane gold 1.6 rollers on my 1988 iroc 5.0 with no other modifications at 60,000 miles. After 4 years of moderate abuse and 80,000 ADDITIONAL miles on this motor I've had not one problem with the setup. I changed to k&n filters, and modified the maf at the same time so the gains I felt might be from all three mods.

 

No problems whatsoever. I was one of the first guys on the original thirdgen board to do this mod (Crane Gold Race self-aligning 1.6 rockers narrow body for centerbolt heads).

Tim

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TRAXION's 1990 IROC-Z
Best Time = 12.244 @ 112.51mph (1.778 60' / 7.819@88.32mph in the 1/8)
All Natural. No Force. No Drugs. Stock Bottom End. Stock Body Panels.
Gunning for NA 11's with bigger cam, bigger stall, and bigger exhaust.
-=ICON Motorsports=-
Moderator: PROM board at thirdgen.org