Brad95

Building up a 6.0 for street duties in my 70s ozzie ute. Decided to build around the stock bottom end for now. Future plans for more cubes in year or 2. Have gone with:

sbe L77 6.0
melling pump
rollmaster chain
ls3 heads
comp trunnions
BTR stage 4 kit 233/250 .618 .596
johnson lifters
super victor
edelbrock 4 barrell
holley hp efi

Originally installed the cam dot to dot. Sure enough cam was 2* advanced. Degreed the cam in spot on once retarded 2* on the rollmaster lower sprocket. Set tdc using the piston stop method. Cam is degreed at 8* btdc at 0.50" as per cam card. Lift measured with dial indiactor directly onto lifter.

Installed checker springs, made a solid lifter, old gasket, torqued head down, comp adjustsble pushrod used to set zero lash. Dial indicator directly on spring retainer measuirng lift then pushing rocker by hand to check ptv making sure dial indicator returns to where it was previous.

Ptv numbers come back as follows:
Intake - Exhaust -
8* .120 340* .107
tdc .053 345* .082
5* .032 348* .074
8* .025 350* .069
10* .025 353* .068
12* .027 355* .072
15* .037 358* .082
20* .063 tdc .092

Intake 0.025"
Exhaust 0.068"
These seem extremely tight. I know this cam is tight. But looking for opinions on if this is ok or not? Im awaiting an email from Brian but he must be away atm. Any guidance much appreciated.
Cheers - Brad

ColeGTO

iTrader: (3)

Definitely too tight for me. On a hydraulic cam, I'd want at least .060" intake and .100" exhaust.

FYI
Retarding the cam will give you MORE intake clearance and LESS exhaust clearance
Advancing the cam will give you LESS intake clearance and MORE exhaust clearance

Looks like you will need to put some valve reliefs in the pistons.


Cole

farmington

iTrader: (14)

Or maybe go .020 thicker on head gasket.

98CayenneT/A

Cutting valve reliefs is not that bad. You can get the cutters for about $200 from Lindy

I had to cut reliefs and they turned out pretty good.

ColeGTO

iTrader: (3)

You can also ask around for an old valve and make you own cutter by grinding a groove and then relieving the backside by hand. There's a few pics on Google.





You can also do it by using adhesive backed 60-80 grit sandpaper on the face of the valve and cut to the OD size of the valve.





Get creative, but be sure to watch your depth of cut when you do it.



Cole

Brad95

Cheers guys,
i will relief the pistons.
what clearances should i aim for?
.060 intake and .100 exhaust? What about radial clerance? .030+?

Nows the time to mill my heads is .025 off worth the extra bump on compression? Or should i just go with a thiner headgasket for now?

NEstyle

iTrader: (1)

Chose a head gasket to give the quench you want, mill to give the compression you want, and fly cut to give the PTV you want. Think about it in that order. The Lindy cutters are sweet and worth it.

mark aubele

I'd be more concerned with getting the quench tight first.

Brad95

Thanks, my first time dealing with quench/piston head/valve clerances. Learning lots!

Is it worth checking quench and seeing if its possible to squeeze it a little tighter? Or not much gain? Whats standard clerance?

NEstyle

iTrader: (1)

I am running 0.034" with an aluminum block. I'm no expert, but many people say that's about as tight as you want to go. A 0.040" head gasket on the typical LS (piston out of the hole 0.006") will put you right there.

Brad95

Thanks, too check do i just use a deck bridge with an indiactor and get the piston out if hole height, with rocking the piston. then subtrct that from my gasket thickness?

is there much gain left on the table not going tighter?

KW Baraka

iTrader: (7)

Worse possible solution......going with 'extra thick' head gaskets. This will screw up quench like nobody's business and would result in a poor performing engine.

Flycutting the pistons or going with a different cam are much better solutions.

KW

Brad95

Checked piston height. At top and bottom of each piston. Added the two together then divided in half. Numbers varied abit. From .005 to .008, Average is .007 as it should be? Is it normal for abit of variance? Could possibly be my inaccuracy tho.

i will go with a .040 gasket and mill .025 off the heads. Which gives me about a 64cc chamber?
According to a compression ratio calculator that puts me at 11.1 to 1? (4" bore, 3.62" stroke, 64cc, .007 deck height, .040 gasket, 4.030 gasket diameter) does this sound right?

then i had .025 and .068 ptv with .051 gasket. So .025 mill and .011 thiner gasket id be at -.011 and +.032 ptv clerance. So if i cut .050 and .060 into the pistons ill have about .040 and .090 ptv. Does this sound right/enough? I will check ptv after cutting of course.

will -.035 (thinner gasket+mill) mess with my supervic manifold fitment?

-sorry for the essay, first time doing this having someoe double check my calculations would be great! Cheers brad

ColeGTO

iTrader: (3)

.040" Intake and .090" Exhaust is too tight. Stick with .060" Intake and .100" Exhaust.

Once you get the first intake and exhaust cut, you can use a "drill stop" on the stem of the valve to set your depth for the other cylinders. But, be careful if the valve guide heights, valve installed height, etc. aren't all even across all cylinders, your cut depths will vary. Maybe measure from the top of the guide to the tip of the valve (use same valve for all cylinders) to see how close you might be before you cut any.

.035" total change in deck height should affect manifold fitment.

Brad95

Finally finished cutting. Used a pair of ls1 valves i pad welded up and machined to be oversize, then cut reliefs into it. Worked well. Ended up at .060+ and .100+. Heads decked .030, .040 gaskets.

Heads assembled and torqued down with arp bolts, oil pump and dampner/chain all final insalled.

Next is measure pushrod lengt, which i may need some opinions on what preload/length fits best.

And build a set of headers. Currently have 1 3/4 4-1s. Obviously i want minimun 1-7/8s. Whats opinions on 2"? I figure if im building a set why not the bigger and to allow for future bigger cubes? Or will the 2" only loose midrange on this motor?

ColeGTO

iTrader: (3)

Nice! I like the creativity here. Looks like it worked out pretty well for you.

Be sure to polish/deburr/round the edges of the relief cuts in the piston though.

I think 1.875" tubes would be sufficient for a good "street" combo. 2.000" tubes are better suited for 400+ inches and/or LOTS of RPM.

Che70velle

iTrader: (6)

Agreed.

Brad95

I did de-burr the sharpe corners only slightl with a de-burring tool. Is this sufficent or do i need to put a decent chamber on the corners?

cometic gaskets are torqued down. But alot of people are reusing them? If its ok too ill pull the heads and chamfer.

G Atsma

Just as long as the edges aren't sharp enough to get hot enough to pre-ignite the mix.