I am fully porting & polishing a set of stock 305 heads for my car but I have a few questions having to dow ith valve springs.

I have a complete set of vortec valve springs, light weight vortec retainers, and lockers.

What I need to know is that I heard I cannot use the vortec light weight retainers because of some compatability problem with my heads, is this true?

Also, vortec valve springs will work fine with my 87 L98 cam and 1.6 rockers, I know they can handle the lift but what I'm wondering is if there to stiff?

And the last question is the vortec springs did not come with dampners, a friend of mine told me to remove the dampners from my old springs and put them in the vortec springs but that it's not necessary, I can run the springs fine without the dampners.

If someone can answer my questions that would be great

 

The Vortec valve springs are a little light on spring pressure.
they will work but only to a modest rpm limit.

Stock diameter hi perf replacement valvesprings are not expensive. I would "spring" for some new springs. The vortec retainers will work fine. So will stock
type retainers. The installed height will be slightly different between the two. You should check and verify full lift+.060" clearance between all interferance points, yourself.
The exhaust spring seat on those 305 heads are machined deeper. this allows for the thicker stock 305 exhaust seat retainers/rotators.
The difference can be made up for by using a .105" stack of spring shims on each exhaust spring seat.

Consider drilling and pinning the rocker studs to prevent the stock pressed in studs from pulling up.
the pushrod slots that are machined in the heads to guide the pushrod and keep the rocker aligned may need to be lengthened
toward the stud for 1.6 rockers. You can use a "Louis Tool" and drill to do this.

 

F-Bird,

Are you certain on the take-up for the rotators? I've measured spring height differences closer to 0.100" with the rotators, not 0.105". I know that's splitting hairs, since valve spring installed height isn't that critical, and I've measured only used rotators, but what exactly have you measured with the rotators?

 

There is no point in trying to cheeeep out to the extent of re-using a bunch of stock truck garbage. Throw it in the trash where it belongs.

Get a set of decent springs and the hardware to match, and install them correctly. You'll have far less opportunity for problems, and a longer-lasting finished product, and the $75 it took to get decent springs and retainers (that you'll have the comfort of never having to worry about again) will disappear in the noise floor of the whole expense of owning, operating, and modifying your car.

 

These vortec springs ARE brand new, they have never been used, as well as the retainers & lockers. Besides these springs are good for the L98 cam and 1.6 rockers combined lift. The day I put a nice big lumpy cam is the day I will get better springs, I just wanted some better than stock stuff that will do the job fine, I rather not spend 75 bucks to get some springs, then spend another 75 later to get another set of springs when I get a big lumpy cam with crazy lift & the previous srpings are now useless.

I paid 15 for the new springs, retainers, & lockers mind you, damn good price.

I am doing this the right way, there's no cheaping out here aside from the fact I'm going to be doing all the porting & polishing on my heads instead of taking them somewhere.

 

I've measured a LOT of stock 1.25" springs off a LOT of stock heads (but not Vortec stock springs) and they all come in at a seat pressure of about 65-70 lbs and an open pressure of about 220-240 lbs. This is at an istalled height of about 1.700-1.75". I suspec that stock Vortec springs are probably similar if not exactly the same.

There are a LOT better springs out there. Crane offers some 1.25" springs that will drop right in and give you a seat pressure of about 100 lbs and 260 open. WAY WAY better if you plan on spinning over 5500 RPMs even with a mild flat tappet cam.

They work great and I've even used them with the stock rotator/retaners with excelent results.

Just about any stock GM spring will take about .500" lift without binding up (but still not doing a good job of controling valve motion at higher RPMs due to very mild spring pressure) but that's not the big problem- the retainers hit the stock valve guides (or the top of the guide seals more often) at relatively mild ~.470" lift without machinging the guides down some.

 

I'm not looking to rev my engine anything higher than 5k, 5.5k at the most.

 

where is a good place to get valve spring shims? that would add up to .100 on my exaust side?

 

i ordered these from summit

http://store.summitracing.com/partde...art=CCA%2D4753

compcams shim kit .060, 0.030, 0.015, with one of each, it will put you .105"

i was unable to find a .010 shim, so i dont' know that you can hit .100" exactly, but i think .105" is what it should be when you take the rotators off.

 

thanks dewey

 

Here are my notes i made on my first set of modded heads.
A stack of .105" shims seems to be the closest to equalizing the
installed heights when eliminating the rotators on the exhaust side. The other two sets i did up (for me and 350turbo411 {Buffalo NY})
needed the same shims too.
Works out about the best this way with the commonly available shim sizes. {.060, .030 .015"}

MY "416" CASTINGS, PORTED AND MODIFIED

INSTALLED HEIGHT STOCK RETAINER IN.1.734" EX. 1.84375"

CLEARANCE BETWEEN RETAINER BOTTOM AND SEAL IN. .6875" EX. .65625"

VALVE SIZE 1.94" IN. 1.60" EX. (stock valves 1.84" in. 1.5" ex.)

COMBUSTION CHAMBER CC'S #2 HEAD POSITIONED FACING CHAMBER INTAKE UP.
#1 CHAMBER 61 CC'S #2 CHAMBER 60 CC'S (stock chamber 55-57 cc's)

INTAKE PORT VOL. #1 INT. 176 CC'S (stock port 167 cc's)
INTAKE PORT VOL. #2 INT. 178 CC'S

EXHAUST PORT VOL. #2 EX. 66 CC'S (stock port 56 cc's)

SPRING SHIM THICKNESS .03125" OR 1/32

Flow Bench Test

@10" H2O intake ex @28" H2O intake ex

lift
.100" 42 .100 70.1
.150" 63 .150 105.2
.200" 81 .200 135.27
.250" 95 .250 158.6
.300" 112 .300 187.0
.350" 123 .350 205.41
.400" 133 .400 222.11
.450" 135 .450 225.45
.500" 135 .500 225.45
.550" 131 ex 84cfm .550 218.77 140.84cfm