I've read some of the past posts and know that the LO3 has a hydraulic roller camshaft, BUT
why do I want more than 110 lobe separation?

I'm thinking of vortec heads at some point, and it seems like i've read that they support more lift that stock heads. what sort of lift should I look for?

I was looking at something with 270 int & exh, and .5 lift on the int & exh with 110 lobe separation. Am I way off or is this something reasonable?

I'm just really lost any explanation would be appreciated. thanks

 

well, there are a lot fo theories about picking a cam. the easy way to understand it is to think of the way a car sounds. a really rumpity cam is a taller lift/longer duration, that means it has to spin up higher to use all of it's power, where as the more melloow car at idle has less lift/duration and will make power at a lower rpm.
the reason you want more than 110 lobe sep is mostly to make suree there is enough vacuum to support the car at cruising speeds and just off idle. also the stock tuning will not like you for having little vacuum as it can't compensate, but a custom prom can fix that easily enough.
as far as lift goes, it is not the heads that determine what the engine can "support". the lift of the cam shoudl be low enough that the valves do not open so far that there is air flow interference witht he bore wall(that is somewhere between .465 adn .470 lift in a 305) but it can't be so short that it keeps the engien from breathing. also remeber, a cam is just what opens up the engine to use the air that can get into it, if you run a good cam with a stock manifold and heads you will see some gains, but hte most gains will be found be matching components.
the lift of a cam places a lot of limitations on teh duration that it cam support as well. since the engine works as a pump, if the valve is idle for too long it will actually lose air flow since the air flowing past it will stabilize into a constant rate instead of being accelerated into the combustion chamber as it needs to be to mix the air/fuel properly.
the simple version of all i just said is that a cam with a .460ish lift and a duration in the high 20x or low to mid 21x range will be ideal for a 305.

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That is why the LT1 and L98 Cams are good for the L03.

 

and i have a 87 l98 and a 88 l98 cam for sale for $30 plus $10 shipping each~!

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88 Iroc-Z L98, rebuilt T5, ported manifold and plenum, built 355 shortblock, Ported S/R Torquer Heads (2.02/1.60), AFPR, Hedman 1 5/8" 3" collector, 3" y pipe, !Cat, Edelbrock Catback, 3.42 gears WAITING FOR TIMES!! and LT1 Swap!!

 

What are the specs on the l98's and the lt1 cam?

 

These specs vary slightly from year to year

L98:

Duration @ .050 202/207
Lift .413"/.428"
lobe separation I think is 115*

LT1:

Duration @ .050 201/208
Lift .447"/.459"

Lobe separation is either 115 or 117 but I don't have that number either.

 

Thanks for the specs.

If I were to go with something like a CompCams with:

1987-later small-block Chevy w/OEM roller exc 1993-later LT1 K kit Hyd roller RPM range: 1000-5000 Adv duration: 258 int 264 exh Dur at .050: 206 int 212 exh Lift: .480 int .487 exh Lobe separation angle: 110 Good idle

(that is exactly what the web site says about it)

How would I go about getting a prom to compensate for that 110* lobe separation?
CompCams has those different 'kits' that come with certain parts for the install. What all do I need to get with it, so i don't go wasting money on all the extras they are gonna put in?

 

I think you will have idle troubles with a lobe separation that low. I ran a Compucam 2050 with a lobe sep of 112 degrees and had idle troubles in my 92 GMC 5.7 TBI the LT1 cam ran MUCH better. The rumble of the compucam was nice but it through the computer into a fit and I didn't feel it was worth $250 for a custom chip at the time to straighten it out for a 5-10hp gain. I highly recommend the LT1 cam for TBI engines.

 

Nilla head, just get the Comp Roller cam similar/same to the one you sated above BUT having 112 lobe sep. They have them in the catalog, just look around. Might say for "EFI" cars of GENERAL FUEL INJECTION or something like that, but you'll find it.

 

I highly recommend this cam (and so did the guy who built my engine). It is very computer friendly, if I could ever get my spark delivery problems fixed (bad plug wires). Here's a link:

http://www.compcams.com/information/...umber=08-302-8

 

That's a good cam. Perfect for OOB Vortec heads with the .480" lift max!!!