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Topic: engine rebuild/replace options

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engine rebuild/replace options (11/21)
 2/26/11 3:16am
Warp2
Former Member

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Henderson, NV - USA

Vette(s):
1982 Coupe,ZZ383/425HP,Tremec 5 Speed, 354 Dana,VBP Pro Comp dual Mount Suspension, Steeroids Rack & Pinion. Affiliation: Yakima Valley Vettes


Joined: 11/16/2007
Posts: 48

Not many C3s but lots of fives and sixes. Give me holler if your in town,
engine rebuild/replace options (12/21)
 2/28/11 10:52am
75stgryLifetime Member
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Las Cruces, NM - USA

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1975 Stingray Coupe - Yellow/White


Joined: 3/11/2006
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I considered the ZZ-4 replacement engine, but I really wanted to get away from the carbureted engine and also find something that had a roller cam and fuel injection.  My first thought was at trying to install a 2004 Yukon, Gen IV 6.0L we had on hand.  When trying it as a fit we found that too much modification on the frame, steering and A-arm clearance was not really feasible. 

I started looking at the L-31 Vortec engine which was in the 1996 Tahoe’s and Yukon’s VIN code “R”.  We managed to locate one with low mileage 40K complete with computer and wiring harness.

I considered using the serpentine belt system on the L-31, but it would have required complete relocation of Alternator, AC compressor and some clearance problems with the power steering.  The L-31 block external bracket mounting bosses are identical to the L-48, so I remove all the serpentine and replaced the serpentine water pump with a short stock corvette water pump.

The new engine is running at about 300HP plus which is about double the old L48.  In town mileage is around 15 mpg and highway should be over 21 mpg.  With the 700r4 and 3.08 rear-end 2000 rpm is right at 76 miles per hour.  The 700r4 is setup with a switchable electric locking torque converter in 2nd, 3rd and overdrive. It really is nice to have a friend like Dana with a shop and lifts to help bounce the ideas off of and work with. Dana owns Alert Services in Las Cruces, NM and is an avid car buff and friend. 

If you are interested send me your e-mail and I will send you a copy of the step-by-step with pics in MSword or .pdf . 

Lee (technut@comcast.net)

 



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engine rebuild/replace options (13/21)
 2/28/11 5:55pm
Jaws79Lifetime Member
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Sykesville, MD - USA

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1979 Corvette Coupe Corvette Light Blue Midnight Blue interior Mirrored Glass T-tops


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That two-tone yellow looks really cool, Lee! Don't think I've ever seen that before!
 
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engine rebuild/replace options (14/21)
 3/8/11 2:29am
daveo76
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Vancouver, WA - USA

Vette(s):
1976 Silver/Firethorn. L48, 4spd. Original 2 bolt, vortec heads, 9.4:1 CR, Speed Pro Cam: 224/224@0.050, 112 LSA, Eagle Steel Crank.


Joined: 8/25/2005
Posts: 857

Any thoughts on this motor?


Sounds interesting, but the .060 over has me a little worried.  That and he doesn't say what the compression ratio is or what the heads are/valve size/rocker arm ratio, etc.  I figured I'd call him tomorrow and ask him those questions - any others?  Does the block need to be sonic tested or magnafluxed to go .060 over?  I think I'd want to know why he went that far, too.  


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1976 Silver/Firethorn.  L48, 4spd.  Original 2 bolt, vortec heads, 9.4:1 CR, Speed Pro Cam: 224/224@0.050, 112 LSA, Eagle Steel Crank.
engine rebuild/replace options (15/21)
 3/8/11 2:22pm
Adams' AppleLifetime Member
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Duncanville, TX - USA

Vette(s):
#1-1974 L-48 4spd Cp Med Red Metallic/Black deluxe int w/AC/tilt/tele./p/w-p/b/ Am-Fm/map light National/Regional/Chapter NCRS "Top Flight" #2-1985 Bright Red/Carmine Cp.L-98/auto Member: NCRS, NCRS Texas, Corvette Legends of Texas


Joined: 11/8/2003
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That's a later model engine, but a 4 bolt helps. I'd definitely find out why the .060 overbore. Should be ok tho. Flat tops are gonna put you around 9, maybe 9.5 on the compression, depending on the chamber volume of the heads. Piston pin height will make a difference, too....might ask if they are stock pin heights, and what brand/type(cast, hyperutectic, etc).
Cam looks kind mild, imho...


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engine rebuild/replace options (16/21)
 3/9/11 1:19am
daveo76
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Vancouver, WA - USA

Vette(s):
1976 Silver/Firethorn. L48, 4spd. Original 2 bolt, vortec heads, 9.4:1 CR, Speed Pro Cam: 224/224@0.050, 112 LSA, Eagle Steel Crank.


Joined: 8/25/2005
Posts: 857

I called the guy today.  Yep, cam is a little too mild - he actually steered me away from buying that motor.  Small valves, low compression, mild cam -- it was basically built for a truck.  We talked for about 20 minutes on the phone and I think I'm going to consider having him build up my original block.  His proposal: keep my block and heads, 9.0 CR, some porting on the heads, flat-tops, Comp Cams 280 Magnum (.480 lift, 280 duration).  Does that seem like too much cam?  Do I need to be concerned about lopey cams not producing enough vacuum to operate the headlights?  

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1976 Silver/Firethorn.  L48, 4spd.  Original 2 bolt, vortec heads, 9.4:1 CR, Speed Pro Cam: 224/224@0.050, 112 LSA, Eagle Steel Crank.
engine rebuild/replace options (17/21)
 3/9/11 2:39am
Warp2
Former Member

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Henderson, NV - USA

Vette(s):
1982 Coupe,ZZ383/425HP,Tremec 5 Speed, 354 Dana,VBP Pro Comp dual Mount Suspension, Steeroids Rack & Pinion. Affiliation: Yakima Valley Vettes


Joined: 11/16/2007
Posts: 48

Good questions. I worried about it also when i purchased my GMPP ZZ383. Keeping i mind that it is a roller, that might make some difference, but it has .50 lift and i havn't had a bit of problem with vacuum. Headlights, brakes, heater/AC doors all operate normal.
Best of luck.  
engine rebuild/replace options (18/21)
 3/9/11 9:17am
Adams' AppleLifetime Member
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Duncanville, TX - USA

Vette(s):
#1-1974 L-48 4spd Cp Med Red Metallic/Black deluxe int w/AC/tilt/tele./p/w-p/b/ Am-Fm/map light National/Regional/Chapter NCRS "Top Flight" #2-1985 Bright Red/Carmine Cp.L-98/auto Member: NCRS, NCRS Texas, Corvette Legends of Texas


Joined: 11/8/2003
Posts: 20126

280* duration should be fine as far as vacuum(tho it is getting up there). It will be a little lower than normal, but you really shouldn't have an issue with the headlights...they just might be a little slower rising. It will definitely have a lope to it, but.... I'd want a wee bit more compression for that cam to really shine. Might consider shaving the heads a bit to bring the compression up.

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Joel Adams
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(click for Texas-sized view!)
             NCRS

"Money can't buy happiness -- but somehow it's more comforting to cry in a CORVETTE than in a Kia"

engine rebuild/replace options (19/21)
 3/10/11 12:13am
daveo76
Former Member

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Vancouver, WA - USA

Vette(s):
1976 Silver/Firethorn. L48, 4spd. Original 2 bolt, vortec heads, 9.4:1 CR, Speed Pro Cam: 224/224@0.050, 112 LSA, Eagle Steel Crank.


Joined: 8/25/2005
Posts: 857

thanks for the input.  I think this may be the right option.  I'll definitely talk to the builder about shaving the heads.  His estimate seems reasonable so far ($1100) so hopefully that wouldn't add too much.  So my ignorance here: you can't just put taller slugs in or move the piston pin down to get the added compression - beyond 9.0?  

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1976 Silver/Firethorn.  L48, 4spd.  Original 2 bolt, vortec heads, 9.4:1 CR, Speed Pro Cam: 224/224@0.050, 112 LSA, Eagle Steel Crank.
engine rebuild/replace options (20/21)
 3/10/11 9:06am
Adams' AppleLifetime Member
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Duncanville, TX - USA

Vette(s):
#1-1974 L-48 4spd Cp Med Red Metallic/Black deluxe int w/AC/tilt/tele./p/w-p/b/ Am-Fm/map light National/Regional/Chapter NCRS "Top Flight" #2-1985 Bright Red/Carmine Cp.L-98/auto Member: NCRS, NCRS Texas, Corvette Legends of Texas


Joined: 11/8/2003
Posts: 20126

Pistons with a slight dome would work, but adds to the cost considerably, and it would also get into having to either use a high octane fuel, or retarding the timing so much it wouldn't be worth the effort. Cutting the heads is the easiest, and cheapest way to get a wee bit more compression, along with using a thinner head gasket. I think a 9 1/2 comp ratio would work well with the cam you mentioned, and not have any detonation/pinging problems with a decent(93 octane) fuel.
Moving the pin location on the pistons also brings in having to use longer/shorter rods. The piston itself can only go so far up before it sticks out of the block, which is not good, unless it's a diesel.
Flat top pistons, decent heads, and that cam should run pretty well. It won't be a screamer, but it should be fun to run.


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Joel Adams
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             NCRS

"Money can't buy happiness -- but somehow it's more comforting to cry in a CORVETTE than in a Kia"

engine rebuild/replace options (21/21)
 3/11/11 12:11am
daveo76
Former Member

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Vancouver, WA - USA

Vette(s):
1976 Silver/Firethorn. L48, 4spd. Original 2 bolt, vortec heads, 9.4:1 CR, Speed Pro Cam: 224/224@0.050, 112 LSA, Eagle Steel Crank.


Joined: 8/25/2005
Posts: 857

Thanks Joel and everyone else!  It sounds about what I'm looking for - don't think I want a screamer anyway.   Just gotta get the dang thing outta the car nowTongue daveo762011-03-10 21:13:03

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1976 Silver/Firethorn.  L48, 4spd.  Original 2 bolt, vortec heads, 9.4:1 CR, Speed Pro Cam: 224/224@0.050, 112 LSA, Eagle Steel Crank.
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