ok ive read that people are useing gen 2 lt1 cams to cam a tpi 305, now my Q is: can you use the stock lifters (i know you have to use lt1 valve springs) but can you use the stock locks and spring retaners on lt1 springs??

 

if the stock lifters are roller lifters, tes, you can use them, and if the retainer fits the spring, yes, you can use your retainers and locks

 

thanks for the info

 

why can't you put the lt4 cam in it??

 

you can, make sure you cut the dowel pin to the correct length(same as your old cam)

 

so to do a lt1/lt4 cam swap in a 305 tpi, i think you need:
the stock roller lifters
lt1/lt4 valve springs
cam
just slap a turbo on it and dont worry about the cam

 

lt4 cam, thats a little much for a 305 TPI don't ya guys think? i'd stick with a 210-218 duration and .460-.490 lift...just make sure your valvetrain is built for whatever cam you choose, otheriwse your gonna run into more and more problems down the road..

 

The stock heads will only handle roughly .480" lift, over that you will coil-bind and break something. Plus a 305 won't benefit from such a big cam, and may even run slower. Stock valvesprings HAVE TO GO!..
Must make sure your 305 is a roller block, '87 up.

 

Curious, what are the specs on an LT4 cam?

 

stock LT4 cam(not hotcam) is .476 intake/.480 exhaust, while the duration is 203 degrees intake/210 degrees exhaust at 0.050-inch lift. It also has 115-degree lobe centers

 

I have read that GM increased duration/overlap such that the egr system was not required for the LT4. Does the LT4 cam function in a 350 TPI such that the emissions function properly and pass the sniff test? Does the LT4 cam change the engine charactereistics enough to require tuning of the ECM for emissions and operability?

Questions I have had and not been able to find an answer for on the boards.

 

any mod can benifit from tuning, especially major work(intake manifold, cam, heads, ect.), you would probably need tuning to pass a sniffer test, but I have no proof of this

it should be fine after a tune

 

I agree that tuning would be necessary but no clue yet on how much for operability. Those of us in the metropoliton areas of Texas are now subject to sniff testing. I am doing my homework before I build my 350 TPI and trying to get a grasp on what I can do and pass the emissions testing. I don't want to have to go back in and do a cam change because the car can not pass. I am confident with the LT1 cam but not sure of the LT4.

 

A true "drop in" spring upgrade for earlier heads (TPI/TBI/older carb motors) is a set of Crane 99848 springs or Comp 981s. They're for moderate performance flat tappet cams but work just peachy with mild factory roller cams, too. They are designed for your stock valve spring installed height (1.70") using your existing valves/retainers/locks. No machining required on the heads at all. It's a no-brainer drop-in for an application such as what you are planning. Used them several times with stock L-98 cams. The LT-1 cam is very very similar except for having a smidge more lift.

FYI- your stock springs provide only about 65 lbs. on the seat and about 220 open. The springs I mentioned above are about 100 lbs. on the seat and about 280 open. Just for the sake of comparison.

 

thats the info im talking about, u da man