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Old 02-23-2013, 11:14 PM   #16
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cardo0 Apprentice Level Tech I
Default Sorry folks but i'm old school.

Ok, so i read the vlv spring sticky. My research says to run as light a spring as needed to get the job done. The LT4 springs #12551485 are designed for the HOT CAM and used for a much bigger cam on the ZZ383 crate engine. Can't beat the price and uses all the LT1 vlv spring hardware. I don't know why the HOT CAM kit uses 1.6 rockers with that spring - margin to bind is too small for me. Just my observation is lifting a vlv on the "stock" LT1 head past 0.5" is a waste for flow or may even be counter productive.
So for the price i can't see how u can beat the LT4 vlv spring - just swap springs and go with the Hot Cam.
And IMHO the stock LT1 spring is barely enough for the stock LT1 cam(s).

Good luck Workman,
cardo
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Old 02-23-2013, 11:38 PM   #17
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In reference to the LS6 spring, I saw a spec of 1.190 coil bind. With 1.750 install ht and .525 lift hotcam only leaves .035 clearance. If the springs are installed with +.050 locks to get more clearance then you can't use SA rocker arms. This is why I stayed away from the LS6 springs, otherwise I thought they looked pretty good. I suppose I could've bought some retainers and springs and measured this stuff out, but in the end I went with a different spring.
GM has superceded the LS6 spring (12586484) with the LS9 spring (12625033) and Lingenfelter lists that spring with a coil bind of 1.190
http://www.lingenfelter.com/mm5/merc...9#.USzlA90y-Q4
So watch installed height vs cam lift on LT1 heads.


Cardo, I tried the LT4 spring on my hotcam and felt it was loosing control of the valves at 6k. I installed some springs with more pressure and the engine runs much better. After my experience I could never recommend the LT4 springs for the hotcam.
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Last edited by guppymech; 02-26-2013 at 10:47 AM. Reason: Update spring coil bind info.
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Old 02-24-2013, 12:49 AM   #18
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Default GM loves that LT4 spring.

I have no experience with it but curious, did u use 1.6 rockers or 1.5 with the #12551485 spring?

Thx for your reply,
cardo
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Old 02-24-2013, 10:09 AM   #19
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Quote:
Originally Posted by cardo0 View Post
I have no experience with it but curious, did u use 1.6 rockers or 1.5 with the #12551485 spring?

Thx for your reply,
cardo
Not sure on your p/n but I used the LT4 springs (12495494, set of 16 or 12551483, ea). I used them with both 1.5 and 1.6 ratio stamped rockers. As you would expect the the 1.6 rockers where harder for the springs to control at higher revs than the 1.5 ratio rockers.
While the LT4 springs worked and I used them for 3k miles and went to the track many times I suspected they weren't strong enough. To get the engine to rev cleanly up through 58-6000 rpm I had to play around with reducing the lifter preload. I eventually settled on 1/2 turn, now I consider this just a crutch for weak valve springs to limit the amount that the lifters can pump up when the springs loose control of the valve.
After I installed the stronger springs (PAC1212x) the engine runs much better throughout the rpm range and it is pulling hard at 6k were I have my shift light set. I have no doubt that I could benefit from shifting at a higher rpm now and plan to try 6200 next time I go to the track.

My engine has 120k on it and I have thought that maybe my results with the stronger valve springs are due to my heads oem valve job getting long in the tooth. The heads have never been off the engine and it runs great so I really have no reason to suspect the high milage.

Sorry for the long winded reply.
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Last edited by guppymech; 02-24-2013 at 10:14 AM.
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Old 02-25-2013, 08:49 PM   #20
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Default Wow, great info gupp.

Thx for the reply and it made me think enough to do a little research on this #12551483 spring - yes u were right, i posted the wrong part number. Now first i found that spring was used in quite a few GM crate engines (LT4 Corvette, ZZ4, CT350/400 and ZZ383 Engines) and had to wonder why its not working for our homemade conversions. Well i found all those crate engine heads used the same light weight vlvs:
LT4 Valve, Intake 2.00" (50.8mm) Hollow stem Weight:85 grams, 3.00 ounces #12555331
LT4 Valve, Exhaust 1.55" (39.4mm) Sodium filled stem Weight:75 grams, 2.65 ounces #12551313

Where the LT1 valves weigh in much heaver:
LT1 Valve, Intake 1.94" (49.3mm) Solid stem Weight:110 grams, 3.88 ounces #10241743
LT1 Valve, Exhaust .50" (38.1mm) Solid stem Weight:95 grams, 3.35 ounces #12550909

It don't take many brain cells to realize that spring maybe adequate for the light LT4 type valves but not the heavier solid stem vlvs on an LT1 - at high RPM. So now i'm a believer here. But the bad news is now i on search for replacement vlv springs for my LT1.

Thx again gupp,
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Old 02-26-2013, 12:09 AM   #21
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Here's the suggested springs for my cam seat pressure prevents valve bounce Spring rate is stiffness of the coils due to materials and tightness of the windings open pressure or over the nose pressure is what controls valve bounce. Naturally aspirated street strip
110-130lb seat pressure TPI suggest no more than 125lbs seat for hydraulic roller cams.
For turbo, supercharged or Nitroused engines more seat and open pressure is recommended. Above 150lbs seat pressure billet cams or nitrided cams are recommended due to lobes going flat. Stamper rocker arms shouldn't be used with 350lbs or greater open pressure springs.


Cost $150
Comp cams 981-16 beehives Seat 110lbs at 1.7" less at 1.78" Open 292lbs at .525 Lift less than 270 at .505 lift. .525 max lift spring rate 347 lbs/in
Comp Cams 26981-16 Comp Cams Beehive Valve Springs

Cost $ 50
Hotcam springs and cam specifications 101 Seat at 1.78" Open 273lbs rate 331lbs/in
Coil Bind at 1.215 1.78-1.215=.565Lift and the amount of clearance you desire before coil bind .040= .525max lift .050=.515 max lift and .060= .505 max lift.
LT4 Hot Cam Specs


The zz383 uses cam similar to GM 846 Cam 112lsa I.222 E.228 I.509 E.528
Runs valves of the LT4 Makes 425HP @5400rpm with GM Fastburn 210cc heads

Have the machinist doing your valve job turn the valve stems down to reduce weight similar to pro flows also do 30 degree backcut on valves for better flow while doing valvejob and run the LT4 springs with light weight retainers.


Chevrolet Performance 383ci/425HP ZZ383 Engine - JEGS

The main reason for High RPM with the LT1 is the intake manifold it has short runners,
and a large plenum conducive to High RPM power the older L98's were low RPM torquers due to the Octopus manifolds long small cross section runners. Note Ls1 went back to long runners with large plenum.



Good Price on LS6 springs that Dynamic 396 Recommends Cost $80
Valve Spring, Beehive, Seat 90 lbs. @ 1.8 in. more at 1.78" , Open 295 lbs @ 1.250 in. (.530Lift less at .505 Lift), .570 in. Maximum Lift,

Per set
LS6 Valve Springs, Good to .550

Individual LS6 springs with specifications
Chevrolet Performance LS6 Valve Springs 12586484 - SummitRacing.com

Article on Ls6 springs
LS6 Valve Spring Info? - Corvette Forum



Alex's parts springs retainers locks and cups Cost $102
LT1 VALVE SPRING KIT Includes: SPRINGS, RETAINERS, LOCKS & CUPS. - Alex's Parts Sales


KMJ Performance Hobby Stock springs

Cost $25
SBC Chevy HP Valve Springs Up to 550 Lift NEW - KMJ Performance

Retainers Locks $23
Chevy V8 1.250 Steel 7 deg Retainers and Locks SBC - KMJ Performance

Stouter higher lift .600 springs cost $40
SBC Chevy HP Valve Springs Up to 600 Lift NEW - KMJ Performance
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Last edited by Viper; 02-26-2013 at 12:33 AM.
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Old 02-26-2013, 04:32 PM   #22
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Quote:
Originally Posted by cardo0 View Post
......It don't take many brain cells to realize that spring maybe adequate for the light LT4 type valves but not the heavier solid stem vlvs on an LT1 - at high RPM. So now i'm a believer here. But the bad news is now i on search for replacement vlv springs for my LT1......
Ha! You got it !!!!!

A lot of folks don't wanna hear it....but the LT4 springs tend to have issues with LT1 valves with 1.6 rockers.....even with the stock cam!

Don't wanna get in a pissing war with anyone.....but anyone deciding to go with these springs are really tempting fate.

Best of luck whatever direction you go.

KW
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Old 02-26-2013, 06:37 PM   #23
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Quote:
Originally Posted by Viper View Post
....For turbo, supercharged or Nitroused engines more seat and open pressure is recommended. ....
Just to clarify: that's correct for turbo and S/C'd, but not for nitrous.
If the person running nitrous understands what's going on, he'll shift at lower rpm on the spray than for NA runs with that same motor, therefore less taxing on the springs when spraying.
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Old 03-02-2013, 01:25 AM   #24
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Quote:
Originally Posted by cardo0 View Post
Thx for the reply and it made me think enough to do a little research on this #12551483 spring - yes u were right, i posted the wrong part number. Now first i found that spring was used in quite a few GM crate engines (LT4 Corvette, ZZ4, CT350/400 and ZZ383 Engines) and had to wonder why its not working for our homemade conversions. Well i found all those crate engine heads used the same light weight vlvs:
LT4 Valve, Intake 2.00" (50.8mm) Hollow stem Weight:85 grams, 3.00 ounces #12555331
LT4 Valve, Exhaust 1.55" (39.4mm) Sodium filled stem Weight:75 grams, 2.65 ounces #12551313

Where the LT1 valves weigh in much heaver:
LT1 Valve, Intake 1.94" (49.3mm) Solid stem Weight:110 grams, 3.88 ounces #10241743
LT1 Valve, Exhaust .50" (38.1mm) Solid stem Weight:95 grams, 3.35 ounces #12550909

It don't take many brain cells to realize that spring maybe adequate for the light LT4 type valves but not the heavier solid stem vlvs on an LT1 - at high RPM. So now i'm a believer here. But the bad news is now i on search for replacement vlv springs for my LT1.

Thx again gupp,
cardo0



To make a point, it isn't the weight of the valve that needs control as much as the Heavier hydraulic lifters at higher rpm that need controled and are more prone to float at x open pressure due to accelerated ramps/heavy lifters held by ice cube guides and spring steal spider retainer instead of a spring loaded rev kit.

An old school 71 Corvette LT-1 355 with a big flat tappet hydraulic cam (Crower 240 duration @ .050 lift and .525 Lift) and solid stem heavy 2.02 1.6 valves that are heavier than the solid 1.94 1.5's on the Lt1's used to rev to 6500+ RPM with 110lb seat 330lb open springs. It even had a 4-71 supercharger with 9lbs boost which adds to suggested valve spring pressure requirements.

See car #2 My 68 Supercharged Nova barely see the Gary Dyers 4-71 roots supercharger above hoodline.

http://wumingta.tripod.com/pub/id4.html


The 502HO 450HP @5250RPM engine has 2.19" intake and 1.88" exhaust valves. Cam specs Hydraulic roller Duration at .050" lift 211 Intake 230 Exhaust duration Lift .510" Intake and .540 Exhaust. Cam Similar to LS7 427

Valve springs 110lb seat pressure
14097002 Dual 1.487" 110# @ 1.88" 1.37" 316 14096274 12550422 Use with 454 and 502 HO engines


GM Performance Engines | 502 HO | Chevy Crate Engine | GM Crate Motor | GM Crate Engine






Look at the ZZ502/502HP it has 2.25" intake valves and 1.88" Exhaust valves
makes 502 hp @ 5,200 rpm 567 lb.-ft. @ 4,200 rpm


Big Block Hydraulic Roller Cam
Its valve springs only have 140lbs pressure on the seat. Cam Duration at .050" Lift 224 Intake 234 Exhaust cam lift .527 Intake and .544 Exhaust with 1.7 Rocker arms.

Very similar to the CC503 for LT1's.


ZZ 502/502 HO Crate Engine Tech Specs (Part # 12496963) | GM Performance Parts


GM Performance Motor Crate Engine Deals This Week! | Hotrod Hotline


Some early zz502's Had 110lbs seat pressure springs later ones had seat pressure of 140lbs with the same cam.

Valve springs 140lb seat pressure.
12462970 Dual 1.514" 140# @ 1.94" 1.20" 325 12366990 12495690 Use with 502/502 hp engines Spring

Big Block valve spring specifications.
Valve Shims, Springs, Retainers, Seals



Here competition cams speced a customer with the 502/502 a higher lift cam
.557 lift recommended springs with only 112lbs seat pressure.
BBC Valve spring advice • Speed Talk
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Last edited by Viper; 03-02-2013 at 05:39 PM.
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Old 03-02-2013, 12:51 PM   #25
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wow! information overload. Im doing the same build on my car. any questions I had have been pretty well answered here
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Old 03-02-2013, 04:59 PM   #26
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I just checked a complete set of LS6 springs - GM part #12499224 (new, fresh out of the box) - and they spec'd as follows:

Seat pressure at 1.75" installed height: 108-111 lbs
"Over-the-nose" pressure at .500" lift (1.25" spring height): 293-297#
Coil bind: 1.185-1.190"

Summit has these springs for $68 for the set of 16, but also incorrectly has the coil bind spec listed as 1.085".

I mentioned the LS6 springs because I use them in my Vortec builds all the time. They are a drop-in when used with the Comp 787 retainers. BUT, they are best suited for cams with about .525" lift or less...like the grinds I use on my Vortec builds. The biggest cam that I use in my Vortec 383's (truck engines) is .520" on the exhaust side, which leaves appx. .040" clearance before coil bind. This is tight, but with these springs, it works just fine.

Like anything else you read on this forum (or any other), take it with a grain of salt, plan carefully and measure, measure...and measure again...!
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Old 03-02-2013, 08:11 PM   #27
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Dynamic, Thank You for the info on the LS6 springs.
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Old 03-02-2013, 11:23 PM   #28
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Default More parts than just springs.

Thanks for the test results Dynamic - great info. I always liked the idea of using on the shelf GM parts and the beehives are cool because their single spring and no dampner required. But when i read the specs i see the 1.800" installed height needs an offsetting retainer - which one? Next is what max lift do have then? 1.75"? And what 'bout locators? I would think some parts house would sell this as an LT1 kit - but no one does.
Now Alex Parts has an LT1 spring "package" using their own springs. But from what i've read is the dampners won't fit over the stock vlv guide bosses. Owners are running them without the dampners - something not designed for.

I hope Workman the OP doesn't think i'm trying to steal his thread - but getting good response here and they answer the original question too.
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Old 03-02-2013, 11:50 PM   #29
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Default Then what did they weight?

I'm having a difficult time believing your statements Mr. Viper. If you know the weight of those 2.02"/1.6" vlvs then post it. I posted the vlv weights for LT4 vs LT1 and there is at least a 20% difference. And thats not the only difference between them as i recall the LT4 retainers were titainium too. But the lifters where the same - no weight difference. This is a simple comparison with few variables. But trying to compare the LT1 vlv train to flat tappet let alone BB vlv trains would take a book (or two).
And your telling me to have a machine shop turn down the vlv stems to reduce weight sounds like nonsense - that would require new matching guides for each vlv. How much would that cost?
If u know of a good LT1 spring lets hear it. If u want to talk flat tappet cams and BB's try a Gen 1 or Gen 2 camaro forum.

cardo
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Old 03-04-2013, 07:22 AM   #30
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Lt4 retainers are not titanium they are lightweight machined carbon steel.

https://sdparts.com/details/gm-perfo...parts/19171528

See my package of them in the lower left of this picture? A set of titanium Retainers do not cost $20.

http://wumingta.tripod.com/pub/camsprings.jpg


I could not find the weight of production Big Block or Small Block 2.02 and 1.6 valves
I did find the weights for Racing light weight Milodon valves that are much lighter
2.02 Intake 115 grams Milodon 125.6 grams Ferrea , 1.6 Exhaust 97.1 Grams Milodon 101.5 grams Ferrea.

All these $700 2.02/1.6 racing valves are heavier than the Stock 1.94 and 1.5 Lt1 Valves.

Racing Valves From Milodon

The Big Block Light Weight Racing Valves weigh
2.19 Intake 134.4grams Milodon 156grams Ferrea 1.88 Exhaust weigh 128.9 grams Milodon 131 Grams Ferrrea.

Add to that heavier retainers studs larger diameter pushrods etc you have much heavier valve train and valves controled by approximately the same seat pressures springs.

Small vs Big Block? - Corvette Forum

Chevrolet Big-Block engine - Wikipedia, the free encyclopedia


The ZZ502 Valves and standard 2.19 1.88 valves are heavier big block chevrolet valves are heavier but they still run 110lbs and 140lbs seat pressure valvesprings.

The old 350/327 375/327 the 69 302 and the 70 LT-1 350 all had 11/1 domed pistons Mechanical lifter cams steel crankshafts pink connecting rods cammel hump 64cc closed chamber heads 2.02 intake and 1.6 exhaust valves. Stellite hardened valve seats were not common a very heavy cup and retainer was used with valve rotators to reduce wear on the seats. They used regular gas(containing lead as a valve lubricant) and you could buy ethyl at the pump. Dual valvesprings were used to control the old non hollow stem 2.02 and 1.6 valves fuelie heads were angle sparkplug for better combustion.

The 69 302DZ Engine was developed to compete with Fords 302 Mustangs in the Trans Am and other autocross races. Its Engine was very underated at 290HP Gross not net.
The camshaft used was a 30/30 Duntov named after Zora_Arkus-Duntov The 30/30 designated the solid lifter lash settings with a feeler guage unlike zero lash hydraulics the cam was designed early 60's for the 283/283 fuelie Corvette. No roller Rocker arms were used just cast stamped 1.5 Ratio Rocker arms. Screw in studs and Guide Plates were used along with hardened pushrods. These engines were run 7000+RPM. A #140 offroad cam was designed for the 302 in road race competition it had even more duration and lift
than the Duntov 30/30 cam and a powerband of 4000-7000RPM it was designed to work with the Cross Ram dual carburetor intake with more than 1000+cfm airflow delivered by 2 780 CFM Carburetors to Compete with the Fords Cross Rammed Dual Carbureted Boss 302.

Zora Arkus-Duntov - Wikipedia, the free encyclopedia

The real reason the DZ302 SBC revved so high... - Third Generation F-Body Message Boards


Not as much lift as our cams but lots of duration these cams idle at 1000-1300RPM
Camshaft specifications:
Standard 302 (30-30) cam, P/N 3849346
Casting #3849347
254 duration @ .050" (intake & exhaust)
.485" lift (with 1.5 rockers)
114 deg. lobe separation
Exhaust Max lift @ 116 deg. BTDC
Intake Max lift @ 112 deg. ATDC


Valve springs for the even Hotter GM 140 offroad cam 4000-7000RPM Range
GM Part #330585

Dual
1.379"
Seat Pressure
140# @ 1.75"

1.15"

Average spring rate
325lbs compared to the LT4's 331lbs.

330586

10132715

Use with camshaft #3927140

GM #140 Off road Cam - NastyZ28.com


GM's valvesprings #366282 designed for Mushroom tappet and race roller cams with .625"
Valve lift have 128lb seat pressure and spring rate of 406 avg lbs per inch.


Camshafts & Camshaft Kits

Chevy Small-Block V8

Here are valvespring specifications
Valve Spring Retainers

Here is a big heavy old exhaust valve rotator compared to retainer
http://www.rustpuppy.org/chapter1/ror6-4.jpg


Point Much heavier simpler valve trains were controled at higher RPM's by much dual valve springs or single springs with damper. Beehives were not even invented until around 1997 and The LT4 is the 1st chevrolet car that I can remember that came from the Factory with Roller Rocker arms.

The Lt-4 had a 6300RPM redline and did it with self align Rocker arms without Guide plates on self align rocker arms and hardened pushrods.

Point older heavier valves and valve trains were spun at much higher RPM's on Weaker Valve springs.
The 283/283 the 350/327 375/327 and the 302/290 were reved 7000+RPM The 70LT-1 350 Was Reved 6500+RPM on
Stamped steel rocker arms heavier valves Exhaust Valve Rotators with screw in studs guide plates hardened pushrods and
solid lifter cams.

The only things really different are Hydraulic roller cams and the heavier hard to control hydraulic lifters.


The zz383 Has a Factory Suggested revline of 5800RPM like the LT1 but has a Gm 846 cam on LT4 Valvesprings.
Cam 222/230 .509 .528 112LSA

As for the LS6 Springs they are rated at 90Lbs Seat Pressure 1.8" installed height. Open Pressure at .575 Lift is 293lbs They have a higher lift before coil bind and that is the main advantage. To Compare to LT4 Hotcam springs use a metric of 10lb reduction for each .05 less valve lift (assuming spring rate linearity for ease of modeling) at .525" Lift the Spring pressure would be 1.70-1.75 Installed height reduces Spring pressure by 10Lbs. .575-.525=.050.

So LS6 Springs have a greater maximum lift of .575" a seat pressure 90lbs an open
Pressure at .525 Lift (to compare with LT4 Springs) of 283lbs.

LT4 Springs Suggested max lift .525" (I suggest .510" with .050 clearance to coil bind)
101lb seat pressure and 273lb open pressure.


LS6 springs allow you to run larger lift cam before coil bind have 11lbs less seat pressure to ward off valve bounce but have 10lbs more open pressure to avoid valve float. At a cost of roughly $30 More than LT4 Springs but you cannot use LT1 retainers or LS1/6 Retainers you have to use 11/32 Stem 7 Degree lock Alex's parts retainers for Beehives or Competion Cams 787 Retainers for Beehive springs.
__________________
93 Z28 T-tops T56 6spd 3.23 Gears,
Mostly Stock.

Last edited by Viper; 03-04-2013 at 07:59 AM.
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