Here's what I did with mine:
- rebuilt original block with .030 overbore, new pistons, original rods reworked, new Eagle crank, 9.4:1 compression ratio. Had machine work done by a local shop and he purchased all parts for me. But I put it all together. (would not have cost a lot more to have machinist do the assembly, I just wanted to do it myself)
- Bought used Vortec heads (they were used on '96 and later 350 powered GM trucks). Best production heads GM ever made for vehicles with a 350. Had those reworked by the same machinist.
- Speed pro cam (if I were recommending, I'd say go with comp, I did Speed-pro since my machinist could get them for a good price). Roller rockers, new pushrods (but old would have worked).
- GMPP aluminum intake. There are not many intakes available that fit the Vortec heads and also fit under the stock hood of a Corvette. I think there is an Edelbrock that would have worked as well.
- Original cast iron "rams horn" exhaust manifolds. I did a little bit of porting on them myself. Not a bad option if you want originality, simplicity, low cost, and less heat under the hood. There are many on this site that say headers are a must, but I like my torquey new motor and feel that headers provide the most gains at higher RPM, where I do little of my driving.
- Original style Quadrajet carb. Q-jets are good for our cars when they're street driven. They have small primaries and huge secondaries so they CAN get good fuel economy, if driven judiciously
. You need to get a good book and a good rebuild kit from a reputable company to get them set up correctly. I'd recommend Cliff's High Performance for both.
- I already had true dual 2 1/2" exhaust with Magnaflow mufflers. I had made this mod a few years before doing my engine and I'm not sure I'd recommend it by itself. It probably gave me some gains in HP at the higher end, but I feel like I actually noticed a torque loss at the lower end. Not sure a giant exhaust system is what a stock L-48 needs. Made it sound better, though!
So would I recommend the approach I took? Maybe. Depends on how into things like this someone is. There were a lot of evenings spent out in the garage and a lot of $$ spent on a lot of things. (Example: tools. Lots of tools that I had to buy to finish this project). Not sure I saved money over buying a crate motor, but I'm pretty happy with the result. I've got a fairly high-po original motor, that runs well and sounds and looks cool.
Good luck!
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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.