yep that makes alot of sense

 

hmm well if its only that small lift the .580" springs I have on there now should be fine... fjdkalfjdksla am I wasting time putting new ones on or is that what that dyno would look like w/ coilbind?

blah!

 

With lift close to .600 plus 1.6 rollers you are going with 7.200 or better pushrods right? With my 987-16 springs and 1.6 rollers, I measured the geometry and noticed I would have to go with 7.200 pushrods, that's with the lift of the 306 cam, and it only pushed close to .576 if I remember correctly. I could be wrong, but it would be a good idea to go with a spring rated to .650 which is going to be a double spring or triple depending; and with a spring that hard you will need hardened pushrods and not stock ones either.

 

Just an FYI for everyone, CM lists their lift with 1.6 rockers (it says above the chart).

 

NO, they will not be fine. If your springs are rated to maximum lift of .580, and you up the ratio to .592, you will have what happened to me happen to you look at my page in sig with pics of the LT4 springs that are supposedly rated at .550 and I used 1.5 ratio rockers and 306 cam with lift to .541. Then decide if you want to take that chance with your motor

 

Although I have not started the engine yet, I have installed the
Comp 26915 beehive springs on my otherwise stock LT1 heads.
Based on the research I have done these sound like excellent
springs. Coil bind is @ 1.085" and I ended up with an installed
height of 1.745" using Manley CNC spring seats (PN 42437-16)
and custom machining the OD down to 1.32". Comp 795-16
retainers and 614-16 locks (+.050) along with the .062" thick
seats resulted in the installed height of 1.745".

I spent a lot of time trying to locate an off the shelf spring seat
that would work to my satisfaction and did not find one. The
Manley seats were the closest option. If you wouldl like some
additional installed height you can machine the thickness down
on the seat as well. I definately do not recommend using the
stock or the LT4 seats in this application as the spring does not
sit flush.

If you have stock heads and use the 26918 springs you can use
the same setup and have .660" to coil bind (1.745-1.085). The
desired safety margin is kind of an individual preference. I like to
have .050" minimum and some guys are OK with less. So take your
desired safety margin and subtract it from .660" and see if it works.

I would recommend that you consider machining the thickness of
the seat a bit to increase the installed height and reduce the seat
pressure a bit. The 26918s are pretty stout and at 1.745" are a
bit high on the seat pressure at 145#. The 26915s are in the 120#
range installed at 1.745", which is fine for my setup.

 

that number 1.085 bind is pretty small do you think?? Most recommend a minimum of 1.150

 

1.085" is the height at which the spring coil binds as provided by
Comp in their data sheet. The safety margin is added to this to
determine your useable lift range. As I said before, each person
has a different level of comfort regarding coil bind. I personally
like a minimum of .050". If you look at the hotcam and the LT4
springs you only have about .035".

Your number of 1.150" provides a .065" safety margin which is fine
too. I am running the Crane 227 with .553" lift on the exhaust side
with 1.6 rockers. 1.745"-1.085"-.553" = .107" which is a considerable
safety margin.

The other important consideration when going with high lifts is the
retainer to valve stem seal clearance. I have heard that stock heads
are only good/safe up to about .580" lift.

 

Once I was lost, but now I'm found

 

Ok, thanks a bunch man, lots of info to read over and over again till I understand

you machined the seats down for more clearance even w/ .107" clearance? Just to be sure?

that is why you machined the seats down right? please correct me if I am reading it wrong.

also your locks are not stock?? do they also raise the installed height?

thanks again

 

I did not machine the seat thickness, I only machined the OD of
the seats in order to fit in the stock valve spring pocket which is
in the 1.34" range. The Manley seats were 1.57" OD originally. The
thickness of the Manley seat is .062" and was not modified.

Quote:

also your locks are not stock?? do they also raise the installed height?

In order to achieve the heighest installed height I chose to use
the Comp +.050" super locks and the 795-16 retainers. I also have
a set of regular Comp retainers and 7* locks. The problem with the
7* setup was that the installed height was 1.73" and was too low
for my comfort. Due to differences between the 7* and 10* retainers
you only end up with +.015" when going with the +.050 super locks.
This sounds strange but makes sense if you compare the two
retainers side by side. I would have preferred to use the 7* locks
and retainers and have machined the thickness of the seats down
about .015" but did not have the time to do so.

You could also go with the 10* hardware and machine the seats
down .150" and end up with an installed height of 1.76". It would
be really nice if an off the shelf seat was available that was .035"
thick. The LS1 seats don't work either.

 

hmmm so you suppose maybe that was my problem w/ these valvesprings I have on there now was that the stock seats where used? I am pretty sure now after reading a little more that my retainers are slapping the stock valve stem seals and causing it to eventually bend them or shatter the valvespring? I will take pictures but it looks like on each valve stem seal there is a little ring missing of metal and i saw some shavings
hope this didnt get down in the motor but if it did what went out?

I heard a clunk when the car died, would ignition coil go out and make the motor die instantly? or the fuel pump? these are the other 2 things I will check as soon as I get the heads back on and "try" and start it

 

anyone know the stock install height on stock seats/valve stem seals?

I really need to know this to know if i need to change the seat or not, thx.

 

Correct me if I'm wrong, but aren't the LT4 springs rated to .525" valve lift? I know they're right at the limit with the LT4 Hot cam kit.

 

They are.