ricky223

I'm putting a LT1 cam and 1.6 ratio roller rockers on my 87 305 and am wondering what valve springs i need?? I have found that i need like 1.7" installed height and 1.250 O.D. I've also read something on here about rotator something and to get regular retainers,but it will change installed height? How will I know if everything is good when i put them on? Also i was looking at the cam and it looks like their is no lobe for the fuel pump, i guess i have to get an electronic fuel pump? the cam is out of a 96z28. anything appreciated.

Apeiron

How do you know that if you haven't chosen the springs yet?

F-BIRD'88

What cylinder heads are you working with?
if you're working with the "081" 305 TPI heads, here is what you do.

get this complete Howards Cams spring/retainer locks and seal set kit
http://www.competitionproducts.com/p...sp?number=VSA3
from Competition Products

add a spring shim package
http://www.competitionproducts.com/p...sp?number=4753

Set your valve spring retainer installed height for 1.70" to 1.72"
You'll know its right when you actually measure your spring retainer installed height of each spring and adjust it with the shims in the kit.
When you swap the stock 305 head exhaust rotators for the new conventional spring retainers you'll probabily need a .105" stack of 3shims on each exhaust spring seat ((1) .060" +(1) .030" + (1) .015") It's up to you to check and verify this.
The intake spring seats will likely only need 1 .030" shim on each.
Again its up to you to check the spring heights for yourself.
1.70" to 1.72" is good to go. Less than 1.68" installed height is too tight.
not that hard.
You can buy a spring height mic or make a simple go-no-go checking gauge from sheet metal or welding rod 1.70" using a micrometer or dial caliper to measure and cut your home made gauge tool. Make 3, out of welding rod.
1 1.72" 1 1.70" and 1 1.68" rod/checking gauge.
Then, just like GoldieLocks, find the shims that are "Just right".
Not that hard.

ricky223

i've got the stock heads, lg4 carbuerated.

F-BIRD'88

Doesn't tell you a lot. but the TBI swirl port heads will most likely require a similar set up when you eliminate the exhaust rotators.
Most of the heads like that have deeper exhaust spring seats to accommodate the extra factory rotator thickness.

You can handle making up a few home made checking gauges and checking for yourself and adjusting the installed height as required using the shim kit, can't you?

ricky223

maybe. this will be the first cam i've done. first time messing with springs. when measuring the installed height do i go from the bottom to the top of spring?

Orr89RocZ

iTrader: (20)

comp 981 springs will work great for that cam and are a factory style replacement single spring.
same with those howards springs, just a cheaper spring.

I dont think you really need to measure much out. factory installed height thought was around 1.700" comp springs are rated at that installed height if i recall. Probly just slap it all on and not worry about it. even if its alot taller installed height, the spring has enough pressure for that mild cam.

I have heard you dont need to put on the rotators either. I dont know many ppl that run those things. My AFR heads dont have them

F-BIRD'88

https://www.thirdgen.org/forums/tbi/...-ultimate.html
This thread should keep ya busy.
Apparently there is some variation in the LT-1 cam specs from different cars and years.

https://www.thirdgen.org/forums/atta...1cam-specs.gif

You also want to check the clearance between the bottom of the spring retainer and the top of the valve seal on the valve guide. make sure the seal is all the way down on the guide. You need .050" more than what ever your maximum valve lift is going to be.
1.5:1 valve lift X 1.0666 = new valve lift using 1.6:1 rockers.

ricky223

thats what i was looking for, just slap it on. after installing the springs how will i know if it's not right? i've heard a lot about using shims.

ricky223

it says page not found for that first thread

Orr89RocZ

iTrader: (20)

well its best to check to see how much clearance you will have from bottom of retainer to top of the guideboss/seal. that should be .050" of clearance, which it probly wont be. given Lt1 cams seem to be around .450" of lift, and stock heads are/have been known to have contact at .470-.480 lift. Some may have more than that.

I think .020-.030 is close but many have done it without problems if you use a good spring. I know i've run .459 lift on my stock L98 heads which are said to have clearance issues at .480 lift. thats roughly .021" clearance tho. I havent checked tho to see if they ever contacted.

i want to say you will be fine if you just slap new springs in, but always should double check retainer to guide clearance to be sure. Dont want bent/broken pushrods

F-BIRD'88

Go to competition products and change the search box to "idem number" and enter VSA3.

if you want to use the slap it together and hope for the best method, just rev the motor up real high (ya higher than that, Don't be a wossy) If the push rods stay straight and the valves stay quiet Y you're good to go Hommer.