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2/23/11 1:21am - Original Message: 'engine rebuild/replace options'
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: 830
So in my previous thread I posted that I'm giving up on getting the bolt removed from the end of the crank. Going to start (OK, continue) thinking about options for rebuilding/replacing.  (I've thought about this a lot lately).  My criteria:

- Looks and sounds retro, but numbers matching not a priority.  To me this means, stock exhaust manifolds, orange block and heads, original valve covers, starter, Q-jet etc.  I have an edelbrock performer intake that's painted orange so that's close enough for me.  
- Shooting for 300 HP or close.  This would need to be done using the criteria above and 9.5:1 or less compression, mild or semi-mild street cam, 1.94 heads, but I do already have true 2 1/2" dual exhaust with Magnaflows.  
- Now the tough part - cost.  ZZ4's and the like are out due to budget constraints.  I think I've got two or three options to fit within the budget, or close.  

1. Rebuild my original two-bolt.  .030 over, new pistons and crank, new cam kit, re-work the existing heads or find some re-worked heads on craigslist.  Many existing parts could stay since they're brand new, such as oil, water, fuel pumps, timing set, etc.  
2. Find someone on Craigslist that ran out of money for their project, but already built the motor.  Seems far-fetched, but I've run across a few lately that should work with my criteria.  I'd insist on receipts for parts and labor and would hopefully be able to get references for any shops used.  
3. Find a four bolt bare block and build it from the ground up.  Probably my favorite option, but not sure it will fit the price criteria.  

Does any of this sound reasonable?  Advice?  One of the biggest questions I have regards my stock 882 heads.  One posting I saw on a different board was that these are the "best of the worst" SBC heads.  Is that an accurate description?  Are they build-able for 300 HP?  And what about the 2 bolt vs. 4 bolt question?  Seems like consensus on this site is 2 bolt is adequate for most of our applications with the exception of outright racing.  

Sorry for the long post.  I'm in the process of organizing my thoughts and this helped.  Maybe it will open up an interesting discussion.  


____________________________________

 

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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2/23/11 10:19am - Reply: 'engine rebuild/replace options'
fp_vetter72 Lifetime Member
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COPPERAS COVE, TX - USA

Vette(s):
1972 corvette stingray convertible 2007 coupe

Joined: 7/6/2002
Posts: 412

You might think about what I did, I bought a GM crate motor which comes with a 3 year 50,000 mile warrenty. Mine is a 290 HP and all I did was put all my assc stuff on the new motor. When you see the motor it looks original, only a corvette person would know it's not original. The only thing I had to do with the new motor was drill one hole to mount my wire sheilds below the heads, they must have forgot this one because the other side was drilled. I have my original motor all sealed and on a stand along with the original tranny, I went to a 700R4. all this can be put right back in for that all sought out number matching car. Just remember, do what you want because you drive it,just dont do something that cant be undone later.



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2/23/11 1:54pm - Reply: 'engine rebuild/replace options'
Adams' Apple Lifetime 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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I've seen Fred's car, and the engine does look stock.
 Since money is prolly gonna be the deciding factor, I would go with what you have, and build it up a wee bit. Remember, the LT1 put out over 300hp, but they did have a little higher compression, and solid lifter cams. You can still get a hydraulic cam that will work with the 9.5cr, and the heads you have, but the intake and exhaust is really going to determine IF it will meet your "goal" of 300hp.
A 2 bolt block is fine for what you want...


friggin spelchek
Adams' Apple2011-02-23 10:55:21

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2/23/11 2:53pm - Reply: 'engine rebuild/replace options'
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: 830
Thanks, guys.  The GMPP 350/290 is a good option - I may consider that in the end.  It'd be stretching the budget (looks to about $2K) but a possibility nonetheless.  Regarding $$ I know there are other things that will add up: probably will get the Q-jet rebuilt for a better breathing engine, and definitely will do a clutch kit.  I'm sure other things will pop up, too.  The nice thing about using my existing block for the buildup is I only buy the parts I need.  

Fred - so I'm assuming you painted yours orange before dropping it in?   Any pics?




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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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2/24/11 12:16am - Reply: 'engine rebuild/replace options'
fp_vetter72 Lifetime Member
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COPPERAS COVE, TX - USA

Vette(s):
1972 corvette stingray convertible 2007 coupe

Joined: 7/6/2002
Posts: 412
yes the motor is painted orange, it's been about 5 years now and it still looks great. I do have some pics but I'll have to find them, not sure which computer I have them onConfused

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2/24/11 12:17am - Reply: 'engine rebuild/replace options'
2nd2ja Gold Member
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Lino Lakes, MN - USA

Vette(s):
71 Coupe LS5 454 Auto

Joined: 1/8/2009
Posts: 138
Crate motors save mainly time- it's an instant pop-it-in deal. Many times, building engines takes way longer than first planned out. Remember, shops need many customers to sustain themselves. Every engine I had built took at least a month to get.
 
That said, looking at that 290 hp crate is a bargain, but it's pretty tame. Might as well start with at least the 300hp version.
 
If you find a reasonable shop, build your orginal if you got the time.
 
I come from a long line of engines and different cars- this is my first Vette, though. I get a sense and hearing all over that the C3's value is enhanced by orginal engine numbers... something you hardly ever see in Chevelles, Camaros, etc.
 
It's odd but Vettes seem to be  in a different league when it comes to swapping parts. Everything is just plain expensive.
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2/24/11 1:56am - Reply: 'engine rebuild/replace options'
suncountry Lifetime Member
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Moses Lake, WA - USA

Vette(s):
1976 L48 4-spd, Mahogany Metalic exterior, Buckskin interior 350ci/350hp, 3rd owner, fiberglass spring, 255/50-16's Torq-Thrust II

Joined: 4/16/2005
Posts: 2134
When it was time for my tired original smog motor to come out I found a lightly used GMPP 350HO as a replacement. I still have the original motor but with out new heads it was not going to make much HP. If you are going to rebuild your motor, you are going to need better breathing heads. Vortec heads are inexpensive and will increase air flow.

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C3VR Lifetime Member #110 We are all young at heart Glen
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2/24/11 2:58am - Reply: 'engine rebuild/replace options'
Warp2
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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
Glen gives sound advice. Vortec heads are available in any junkyard and they are a steal.

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warp 2
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2/26/11 12:16am - Reply: 'engine rebuild/replace options'
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: 830
Thanks for the discussion.  Vortec heads are a good idea and I have considered them, but you need a different manifold for them, don't you?  And different valve covers?  And do all the stock accessories bolt up?  I won't just re-use my original heads as is -- I'll either get different ones or get mine re-worked a bit.  

Warp 2 - I grew up in Yakima, my folks still live there.  Are there many C3'ers in town?  


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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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2/26/11 12:33am - Reply: 'engine rebuild/replace options'
suncountry Lifetime Member
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Moses Lake, WA - USA

Vette(s):
1976 L48 4-spd, Mahogany Metalic exterior, Buckskin interior 350ci/350hp, 3rd owner, fiberglass spring, 255/50-16's Torq-Thrust II

Joined: 4/16/2005
Posts: 2134
It does take a new intake manifold, but if you want more HP then an new manifold would be in order any way. You do need new valve covers, gives you an excuse to get something shinny under the hood. Here is what they look like on my engine. The 350HO uses the vortec heads. Here are a few shots of how the parts mount up
 


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C3VR Lifetime Member #110 We are all young at heart Glen
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2/26/11 3:16am - Reply: 'engine rebuild/replace options'
Warp2
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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,

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2/28/11 10:52am - Reply: 'engine rebuild/replace options'
75stgry Lifetime Member
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Las Cruces, NM - USA

Vette(s):
1975 Stingray Coupe - Yellow/White

Joined: 3/11/2006
Posts: 24

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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2/28/11 5:55pm - Reply: 'engine rebuild/replace options'
Jaws79 Lifetime Member
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Sykesville, MD - USA

Vette(s):
1979 Corvette Coupe Corvette Light Blue Midnight Blue interior Mirrored Glass T-tops

Joined: 4/27/2008
Posts: 4211
That two-tone yellow looks really cool, Lee! Don't think I've ever seen that before!
 
Barry
 
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3/8/11 2:29am - Reply: 'engine rebuild/replace options'
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: 830
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.
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3/8/11 2:22pm - Reply: 'engine rebuild/replace options'
Adams' Apple Lifetime 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: 19449
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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Joel Adams
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3/9/11 1:19am - Reply: 'engine rebuild/replace options'
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: 830
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?  

____________________________________

 

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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3/9/11 2:39am - Reply: 'engine rebuild/replace options'
Warp2
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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.  


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3/9/11 9:17am - Reply: 'engine rebuild/replace options'
Adams' Apple Lifetime 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: 19449
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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3/10/11 12:13am - Reply: 'engine rebuild/replace options'
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: 830
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?  

____________________________________

 

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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3/10/11 9:06am - Reply: 'engine rebuild/replace options'
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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: 19449
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
C3VR Lifetime Member #56    
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