The 1.8 rockers, let alone 1.6's will add lift, not necessarily duration. It is NOT a good idea to just install those on your stock heads. You really ought to consider a fresh set of springs that can handle up to 0.550 lift first. Then all is good! :coolgleam
I'm planning to install my old set of 1.6's with a new set of Crane springs and I'll see if I can dyno before and after numbers and post for this list.
No I did not. It's running so well I hate to screw with it. I DID swap out the 2.73 gear for my old 3.08 and added an Eaton Pro posi. I also fabbed up a PVC CAI with K&N cone, Iridium plugs, Bilstein shocks, 96 Impala springs and a brake job. That's about it.
It really handles well and getting 18/24 mpg these days is nice too!
ok heres a question....say i did the lt1-lt4 conversion with used intake manifold, gaskets, 58mm tb, cams, 1.8 rockers? would i screw the engine up? would my hp jump from 260 directly to the claimed 400+???? or is it more than that? cause i kno the lt1's used in the vettes had over 300...and cadillac detuned it to put in the fleetwood...how would u retune it?
The short answer is, uh, no.
The long answer is that the LT4 packages never made 400 Hp. You may have that figure confused from the LS6 Vette motors in the Z06's and CTS-V's (2004). I believe GM claimed the LT4 engines made 330 Hp on the Grand Sports (1996). The LT4 conversion kit is pretty much a joke.
LT4 heads are nice, but you can get a good used set of Al LT1 heads and have them race ported, complete for about $1300 and then add a Comp 227 cam or GM 845 cam and make some much needed torque. RWHP would probably go from about 215 Hp > 315 or 325 Hp. Same, if not more on Tq.