floman

iTrader: (54)

I have a stock 2002 LS1 5.7 shortblock and would like to see if someone can calculate the SCR, DCR, and PTV clearance for me. Looking at some ported 853 casting heads that have been milled .050" with a 60.3 CC chamber, and running a Futral F11 cam on 114 + 4 LSA. Any help would be appreciated.

Specs are:
2002 stock shortblock
853 heads milled .050" w/ 60.3 cc chamber with Ferrea 2.02"/1.57" valves
GM graphite gasket .056" compressed thickness
Futral F11 228* 230* .576" .595" 114+4 LSA
using stock rocker arms

cam card specs are:
Futral F11-114 + 4 LSA
valve overlap 2 crank deg
intake
open 4.5 BTDC not sure on this #s smudgey
centerline 110 ATDC
close 44.5 ABDC
duration 229 crank deg
lobe lift .33949 in
valve lift .57713 in
lobe area 27.37 in * deg

exhaust
open 53.3 BBDC
centerline 118 BTDC
closes -2.5 ATDC
duration 230.7 crank deg
lobe lift .35075 in
valve lift .59627 in
lobe area 28.06 in * deg

Thanks
Floyd

gollum

iTrader: (1)

Scr...11.25

Dcr....8.52

Figure with .053 crushed gasket.

gollum

iTrader: (1)

Intake Valve lift installed @110 cl with 1.7 rocker = .1054" @TDC

gollum

iTrader: (1)

You need to figure your "valve free drop"

Free drop? + Crushed Gasket thickness .053 + .070 valve float clearence

Answer should be equal to or greater than .1054@

floman

iTrader: (54)

What do you mean by "valve free drop" ? Forgive my lack of knowledge.
Is'nt that DCR of 8.5 close to the limit on 93 octane?

gollum

iTrader: (1)

"Valve free drop" is the distance your intake valve travels before contacting piston or level surface. Check before you install springs.

My unmilled 243 heads have about .175" free travel "without gasket" before contacting level surface. I checked before install.

8.4-8.5 dcr... 91 octane

8.7-8.8 dcr... 93 octane

floman

iTrader: (54)

Oh, okay. I see what your saying now. Thanks for explaining that to me. Yeah, with a .050" mill that would make it very close. But , since the shortblock is on a engine stand, cutting valve reliefs would be relatively easy if I have to. Well, at least this info will help me in the decision of weather to buy the heads or not.
Thanks
Floyd

gollum

iTrader: (1)

Let's see...say you have .1250 Valve Free Drop with your .050 shaved heads.

.1250 free drop +.053 crushed gasket thickness = .1780 total install free drop @TDC

Your cams intake valve lift @TDC installed @110 cl has a lift of .1054 + .070 valve float clearence = .1754 total cammed intake valve lift

You should be OK without PTV issues. Better yet just clay your pistons. Shoot for .070 clearence or more.

PREDATOR-Z

Gollum, You just can't calculate this, you have to measure, dial method being the most accurate.
Just by knowing the cam and with Ferrea valves and .050 mill , I could almost garantee it wouldn't fit (99%), not with any safe hydraulic street margins.