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Old 02-06-2009, 06:02 PM   #1
swb85
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370ci LS build-up

This isn’t at all truck related (going in my camaro), but figured you guys would enjoy. Before I start, some specs:

-370ci, 12:1 compression
-LS6 crankshaft
-Clevite H-series coated bearings
-Scat 4340 rods, 6.125” long, bushed for floating pins
-Mahle forged/coated flat top pistons, -4cc reliefs, 436g weight
-custom hydro roller cam, LS7 lifters, Comp 7.375” Hi-Tech pushrods, factory LS rockers
-PRC 220cc cnc ported heads, 57cc chambers, 2.02/1.575 valves, dual springs/titanium retainers (good to .660” lift), flow ~320cfm at .600”
-ported Fast 92mm intake, 92mm PTM throttlebody
-NOS direct port nitrous setup (good for 300 shot)
-42lb injectors/custom rails

Shooting for around 500rwhp on motor and somewhere between 650-750 on spray. On with the build!!

6.0 truck block fresh from the machine shop. Was bored/honed with torque plates to 4.03", decks cleaned up and squared, line bore checked, new cam bearings installed.


Here's the pile-o-parts we're starting with!


After a thorough cleaning of the block, we flip 'er upside down and get to work.


On the motors I build, I like to install the cam first. Easier to guide it through the bearings this way IMO, so it gets thoroughly cleaned and doused in assembly lube (I use Royal Purple assembly lube) and it's ready to stab. The Clevite H-series main bearings are also installed at this time.


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'98 Camaro z28: 370ci twin turbo 370ci build
'01 Tahoe LT 4x4: 5.3, longtubes/ory, magnaflow duals, custom tune....wife's DD

Last edited by swb85; 02-06-2009 at 06:12 PM.
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Old 02-06-2009, 06:03 PM   #2
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Re: 370ci LS build-up

The LSx cam is held in place with a retainer plate, similar to sbc roller motors. Cam endplay measured .006", just right.


Here's the freshly polished and balanced LS6 crank being used. The stroke is standard LSx at 3.622".


The bearings are coated in lube, the crank is carefully laid in place and the main caps are torqued to spec. Main bearing clearances were set at .0025", endplay at .005".




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'98 Camaro z28: 370ci twin turbo 370ci build
'01 Tahoe LT 4x4: 5.3, longtubes/ory, magnaflow duals, custom tune....wife's DD
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Old 02-06-2009, 06:04 PM   #3
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Re: 370ci LS build-up

Time for the piston/rod assemblies. This motor will see up to a 200 shot of nitrous, so the top and second compression rings are appropriately gapped to .024" and .028" respectively. The bores/piston skirts are coated in 30wt oil before carefully tapping the pistons home.






Once all the holes are stuffed, the rods are torqued to spec. Rod bearing clearances were set at .0025", rod side clearance at .023".


Next, deck height is measured. This is a very important measurement for figuring compression ratio. After measuring several spots on the piston, they are .012" above deck, right about where I want them for this build.
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'85 Silverado swb: 383 stroker, 10.5:1, vortec heads, 232/238 roller cam, RPM air gap, performer 750 carb, stainless longtubes, 3" duals/super 44's, T56/4.11 383ci build / exterior refresh thread
'98 Camaro z28: 370ci twin turbo 370ci build
'01 Tahoe LT 4x4: 5.3, longtubes/ory, magnaflow duals, custom tune....wife's DD
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Old 02-06-2009, 06:05 PM   #4
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Re: 370ci LS build-up

And our shortblock is assembled!!! Time for some paint......




After a fresh coat of chevy orange, it's time to install the lifters and degree in the cam. The ICL measured at 107 degrees, close enough to the advertised 106 degrees that I do not need to advance/retard cam timing. LS lifters are held in place by these plastic trays.


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'98 Camaro z28: 370ci twin turbo 370ci build
'01 Tahoe LT 4x4: 5.3, longtubes/ory, magnaflow duals, custom tune....wife's DD
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Old 02-06-2009, 06:06 PM   #5
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Re: 370ci LS build-up

Time for the gaskets and heads to go on. The gaskets are multi-layered steel and are installed dry. The heads are torqued down with ARP bolts.








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'98 Camaro z28: 370ci twin turbo 370ci build
'01 Tahoe LT 4x4: 5.3, longtubes/ory, magnaflow duals, custom tune....wife's DD
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Old 02-06-2009, 06:07 PM   #6
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Re: 370ci LS build-up

She looks purty so far huh?


Stay tuned, lots more to come.
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'85 Silverado swb: 383 stroker, 10.5:1, vortec heads, 232/238 roller cam, RPM air gap, performer 750 carb, stainless longtubes, 3" duals/super 44's, T56/4.11 383ci build / exterior refresh thread
'98 Camaro z28: 370ci twin turbo 370ci build
'01 Tahoe LT 4x4: 5.3, longtubes/ory, magnaflow duals, custom tune....wife's DD
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Old 02-06-2009, 06:14 PM   #7
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Re: 370ci LS build-up

Sweet! I'm looking forward to more!
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Old 02-06-2009, 06:14 PM   #8
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Re: 370ci LS build-up

VERY NICE !!!

Don't know the cam specs and as it's a custom grind I'm sure you wanna keep those to yourself, but is that cam going get the dynamic compression down to premium pump gas territory ? 12:1 on the street has got to be fun.
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Old 02-06-2009, 06:23 PM   #9
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Re: 370ci LS build-up

Cam is big (240's/250's @.050"), dynamic compression is 8.65:1. That's getting close to the limits of pump gas, but with a good quench pad (.041") and tune it'll work for my app. The tank in the back will get 92, the little tank in the front will get 110.
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'85 Silverado swb: 383 stroker, 10.5:1, vortec heads, 232/238 roller cam, RPM air gap, performer 750 carb, stainless longtubes, 3" duals/super 44's, T56/4.11 383ci build / exterior refresh thread
'98 Camaro z28: 370ci twin turbo 370ci build
'01 Tahoe LT 4x4: 5.3, longtubes/ory, magnaflow duals, custom tune....wife's DD

Last edited by swb85; 02-06-2009 at 06:23 PM.
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Old 02-06-2009, 06:45 PM   #10
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Re: 370ci LS build-up

With your tight quench and aluminum heads that have the fast burn chamber I`d say you`ll be ok. Thats a nice engine you built there. i would love to build something like that for my 84 but maybe just a bit milder.
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Old 02-08-2009, 12:15 AM   #11
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Re: 370ci LS build-up

At the risk of asking a dumb question....I know very little about the LS engines, but is it common to have the piston above the deck? are they this way from the factory also?

This ought to be a strong engine....
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Old 02-08-2009, 06:54 PM   #12
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Re: 370ci LS build-up

nice build! can't wait to see what it does in the car.
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Old 02-08-2009, 07:31 PM   #13
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Re: 370ci LS build-up

Nice build . My next one will be a LS motor .
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Old 02-08-2009, 10:09 PM   #14
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Re: 370ci LS build-up

Sweet engine build - I'd love to do one of those someday, keep us posted !
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Old 02-09-2009, 10:26 AM   #15
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Re: 370ci LS build-up

Quote:
Originally Posted by Captainfab View Post
At the risk of asking a dumb question....I know very little about the LS engines, but is it common to have the piston above the deck? are they this way from the factory also?

This ought to be a strong engine....
Yep. Around .006"-.008" above deck is about normal on LS motors with a stock rotating assembly.
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'85 Silverado swb: 383 stroker, 10.5:1, vortec heads, 232/238 roller cam, RPM air gap, performer 750 carb, stainless longtubes, 3" duals/super 44's, T56/4.11 383ci build / exterior refresh thread
'98 Camaro z28: 370ci twin turbo 370ci build
'01 Tahoe LT 4x4: 5.3, longtubes/ory, magnaflow duals, custom tune....wife's DD
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Old 02-09-2009, 10:35 AM   #16
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Re: 370ci LS build-up

Steam tubes, knock sensors/harness, oil and cam sensors installed.



....and a quick teaser of what goes on top. I haven't plumbed the direct port system yet, just had to set it on to see how it looks.



Will keep updating as I go!
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'85 Silverado swb: 383 stroker, 10.5:1, vortec heads, 232/238 roller cam, RPM air gap, performer 750 carb, stainless longtubes, 3" duals/super 44's, T56/4.11 383ci build / exterior refresh thread
'98 Camaro z28: 370ci twin turbo 370ci build
'01 Tahoe LT 4x4: 5.3, longtubes/ory, magnaflow duals, custom tune....wife's DD

Last edited by swb85; 02-09-2009 at 10:36 AM.
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Old 02-09-2009, 01:42 PM   #17
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Re: 370ci LS build-up

With the knock sensors and the computer running the show, you'll be able to get away with the compression, but the computer may pull a bit of timing out and that could hurt performance, right?? Just wondering, that is a super sweet build and i too will do one, i have a 5.3 now, and the used 6.0's are getting super affordable, i was just a little freaked about an LS build, but I have seen enough of them, they are not entirely foreign from a Gen I SBC, like I originally thought when they first started coming out. I think i'll build a 6.0 hopped up, but with a carb?! EFI still freaks me out (I know, I am a carb cavemen, but old habits are hard to kill!)
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Old 02-09-2009, 04:05 PM   #18
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Re: 370ci LS build-up

I do all my own fuel injection tuning---I'll be controlling the show, not the computer/knock sensors. I'm getting away with this much compression because of several variables including quench, chamber design, dynamic compression, precise fuel control/distribution, weight/gearing of vehicle etc. This isn't one of those deals that ya slap together and expect it to work, I spent 9 months planning this one.

Thanks for the compliments everyone, I'll keep going with the pics!
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'85 Silverado swb: 383 stroker, 10.5:1, vortec heads, 232/238 roller cam, RPM air gap, performer 750 carb, stainless longtubes, 3" duals/super 44's, T56/4.11 383ci build / exterior refresh thread
'98 Camaro z28: 370ci twin turbo 370ci build
'01 Tahoe LT 4x4: 5.3, longtubes/ory, magnaflow duals, custom tune....wife's DD
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Old 02-09-2009, 06:28 PM   #19
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Re: 370ci LS build-up

probably a stupid question but are the steam tubes the same as steam holes in a 400ci? purpose wise that is
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Old 02-10-2009, 11:13 AM   #20
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Re: 370ci LS build-up

Very close to the same purpose. You can see the tube that connects to the front of each head in the pic above. This is the highest point in the system, which allows trapped air bubbles out and a path back to the radiator.
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'98 Camaro z28: 370ci twin turbo 370ci build
'01 Tahoe LT 4x4: 5.3, longtubes/ory, magnaflow duals, custom tune....wife's DD
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Old 02-10-2009, 10:35 PM   #21
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Re: 370ci LS build-up

thats a pretty bad a$$ setup but I just have one qeustion, why did you go with prc ported heads instead of L92's? I am puting a ls3 6.2 in my truck also, the reason why I ask is because the L92's at .600 lift flow 325 cfm stock.
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Old 02-11-2009, 12:09 PM   #22
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Re: 370ci LS build-up

Valid question. Currently the only composite FI (non-carb style) intake available that fits the L92/LS3 square intake ports is the factory L76/LS3 intake. That intake falls flat on it's face above ~6400rpm. This motor will make power to 7000+rpm. The carb style intake would require cutting the cowl on my 4th gen and run an elbow.....didn't want to go that route yet, it's still a "street" car (to me anyway).

Secondly, those L92's flow a ton of air but do so with a 260cc intake runner and a big 2.16" intake valve. My heads flow about the same as stock L92's, but do it with a much smaller 220cc runner and 2.02 valve.......much better port velocity, cylinder filling and torque for the smaller cubes I'm running. I would like to do a larger cube motor with L92 heads and a carb style intake someday.......
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'85 Silverado swb: 383 stroker, 10.5:1, vortec heads, 232/238 roller cam, RPM air gap, performer 750 carb, stainless longtubes, 3" duals/super 44's, T56/4.11 383ci build / exterior refresh thread
'98 Camaro z28: 370ci twin turbo 370ci build
'01 Tahoe LT 4x4: 5.3, longtubes/ory, magnaflow duals, custom tune....wife's DD
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Old 02-23-2009, 01:52 PM   #23
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Re: 370ci LS build-up

*UPDATE*

Windage tray, pickup tube and pan are back on, along with front cover and crank pulley. Front/rear cover alignment with the pan rails is critical on LS motors, as the pan is a structural piece of the block. The lower bellhousing bolts actually thread into the oil pan.







I'm now in the middle of the nitrous plumbing on the intake (still have the fuel left to do on the passenger side), once I get that done the motor is getting close to completion!!





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'85 Silverado swb: 383 stroker, 10.5:1, vortec heads, 232/238 roller cam, RPM air gap, performer 750 carb, stainless longtubes, 3" duals/super 44's, T56/4.11 383ci build / exterior refresh thread
'98 Camaro z28: 370ci twin turbo 370ci build
'01 Tahoe LT 4x4: 5.3, longtubes/ory, magnaflow duals, custom tune....wife's DD

Last edited by swb85; 02-23-2009 at 01:54 PM.
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Old 02-23-2009, 11:14 PM   #24
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Re: 370ci LS build-up

Finally finished the intake and set it on!





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'98 Camaro z28: 370ci twin turbo 370ci build
'01 Tahoe LT 4x4: 5.3, longtubes/ory, magnaflow duals, custom tune....wife's DD
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Old 02-24-2009, 12:54 AM   #25
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Re: 370ci LS build-up

Where are you going to move the coils and what are you doing for spark plug wires ?
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