I used the search feature and found no answer.

I recall reading on 4.9 rebuilds that LS1 lifters could be used to make the 4.9 safer to rev past 4500 rpm. Is this so? Are they drop-in replacements?

Thanks,
Lou

May have found my own answer in the chart on this page:

http://cgi.ebay.com/ebaymot...Item&item=8022922385

quote Originally posted by lou_dias: I used the search feature and found no answer. I recall reading on 4.9 rebuilds that LS1 lifters could be used to make the 4.9 safer to rev past 4500 rpm. Is this so? Are they drop-in replacements? Thanks, Lou

that would be LS1 springs, not lifters.. the stock 4.9L lifters are roller lifters already, no need to change them out..do not only add LS1 springs, you have to lower the spring seat as well to prevent coil bind. this however dynamically changes the characteristic of the spring too since it isn't as "loaded" when the valve is closed. the stock 4.9L can safely rev to 5500 rpm, it just doesn't generate much power past 4500. if you want to shift the power band north a little and get good power to 5500 rpm, get the drop-in delta camshaft, in addition to longer pushrods, LS1 springs, and get headwork done too.. the port and polish on the heads and intake is what REALLY wakes this motor up the best...it is all documented in rick stewart's thread:

https://www.fiero.nl/forum/Forum2/HTML/061613.html

To me, SBC springs and LS1 springs should represent 2 different animals unless they are infact the same part.

I'm having a head gasket job done. I don't intend to spend money on the heads, I just was curious what lifters to get. The heads only have about 58k on them.

If the springs are good to 5500, then that's ok to me. I do have an Allante intake on it. I don't need/want to rev it past 5200 anyway.

[This message has been edited by lou_dias (edited 07-21-2010).]

Mine revs easily to 5500 using the stock springs. I believe it will rev to 6k without valvetrain mods. 5500 is a "safe" limit but not the max.

There are aftermarket performance lifters out there for this engine. They don't do much except help reduce friction some. Maybe worth a couple pony's at best. Problem is they make the engine noisier. Summit has them if your interested.

quote Originally posted by lou_dias: To me, SBC springs and LS1 springs should represent 2 different animals unless they are infact the same part. I'm having a head gasket job done. I don't intend to spend money on the heads, I just was curious what lifters to get. The heads only have about 58k on them. If the springs are good to 5500, then that's ok to me. I do have an Allante intake on it. I don't need/want to rev it past 5200 anyway.

while it is out, you might as well pnp the heads, it is well worth the money on the 4.9L, even without a cam shange..it really wakes up this engine in particular, just ask PBJ...

and yeah, SBC sprinsg are different than the LS1 springs.. the LS1 springs will have a behive shape

quote Originally posted by stickpony: while it is out, you might as well pnp the heads, it is well worth the money on the 4.9L, even without a cam shange..it really wakes up this engine in particular, just ask PBJ... and yeah, SBC sprinsg are different than the LS1 springs.. the LS1 springs will have a behive shape

If I was doing a full rebuild, then I would. I just want this thing running again.

quote Originally posted by lou_dias: If I was doing a full rebuild, then I would. I just want this thing running again.

then stock springs will be fine... at least replace the cam while you are at it... easy install...goes along with replacing the lifters