L-48 modifications

[wipeout]

HI, I have a 1977 vette with the l-48. About 4 years ago i rebuilt the motor. Kept everything stock except for hooker headers and sidepipe's, aluminum water pump. removed air conditioning.(did not work anyways).

What is the best way for me to go to get about 400 horsepower with this engine. Should I buy a kit from edelbrock or holley (systemax 2) or should i just save up and buy a whole new engine since this is only a 2 bolt main.

Discuss amongst yourselves.

 

[curtis]

Lots of questions unanswered here. Are you going to do the work yourself or hire it done. How much do you want to spend? How much can you really afford to spend? do you have a place to work on it and all the necessary tools? I can tell you that doing it yourself will give you much more satisfaction (in my experience) then paying someone

 

[wipeout]

Well I rebuilt the complete engine myself. So I will do the work myself as I dont beleive in bringing my vette to garages as it seems nobody around here knows how to work on a vette for some reason and just end up screwing it up even more... (bad expriences there).

I was thinking of spending around 2000.... yes I do have the tools and the place to work on it.

 

[Glensgages]

Cylinder heads, approx $1000 (Edelbrock?)
Cam/lifters, approx $200 (assuming timing-chain is still in good condition)
Intake manifold, approx $200 (single plane will help top-end, if it fits)

Considering you're starting-off with 8.5:1 CR, 400 HP might be tough to attain, but you still have approx $600 to play with, and we haven't even picked a carb yet:
a 75 HP shot of giggle-gas should get you 400 HP without really stressing the bottom-end much.

Good luck, have fun!

 

[wipeout]

Woudn't the compression change when I switch heads. How do you bring the compression up... I was reading the holley website and they say that using the systemax 2 system you can achieve 425 horspower. Would this be a wise and simiple way to go...

 

[Jack]

wipeout:
OE L48 pistons were dished with 4 valve pockets/eyebrows. When you rebuilt ... what pistons did you use? Brand & part number would help a lot. Were they flat tops or dished? 4 valve pockets or 2? Also, did you have the block decked? If so, how much was taken off? ALL that ... and new heads... has EVERYTHING to do with Compression Ratio. A 2 bolt main sbc is fine for 400HP plus. Whatever heads you choose, BEFORE you order verify with manufacturer they'll fit your headers in your car.
JACK:gap

 

[Glensgages]

Woudn't the compression change when I switch heads. How do you bring the compression up...

By using cylinder heads with smaller combustion chambers (I'm guessing the Edelbrock heads I mentioned have 64cc chamber, where-as your L-48s have 76cc chambers), whacking some deck-height off the block, using thinner head-gaskets, or pistons with large domes on them (your L-48 pistons probably have deep-dishes, with 4 valve eyelets cut into them....see Jack's comments above above).
My '79 Z28, with 76cc heads, had 8.2:1 OEM, but after a swap to 64cc heads, I believe we figured it out to 9.3+ CR, which worls fine on decent pump-gas.

I was reading the holley website and they say that using the systemax 2 system you can achieve 425 horspower. Would this be a wise and simiple way to go...

I'm not familiar with any of the 'kits' offered today, but watch the wording VERY-CAREFULLY..... "you CAN achieve....."

 

[curtis]

built mine like the magazines and it is great. vortec heads $650 comp extreme energy 262 kit $200. edelbrock performer $230. edelbrock carb 600 cfm $250. that should be the major stuff for u since the bottom is done. your c/r should be about 9.5 so 89 octane is OK. Scoggin Dickey and Pace have the Gm performance parts kits to do this head change and they are very complete. I get great power and super torque with Hooker headers and 2 1/4 duals. smooth idle with plenty of vacuum. I can email you the magazine article on the build if you like.

 

[pasvorto1]

I would love a copy. I sent you a PM with my email address.

 

[NHvette]

I'm about to start buying parts to wake up the old '75 L48.
The bottom end is stock. For now, I plan on going cheap.
Summit iron heads (copy of 2.02 fuelie heads) ... $650 /pr
Crane PowerMax cam set #113942 ... $160
Timing chain set #11993 ... $66
Thin Felpro gaskets #1094 ... $40

This won't get you to 400 ponies, but over 300 easy.
Oh yeah ... already running Edelbrock Performer manifold, Edel carb, and true duals (no cats).

 

[Evolution1980]

Always plenty of threads on the CAC about rebuilding -vs- buying a crate engine.

Use the search function here at CAC and you'll find the threads. For that much HP/Tq, I suggest just buying a new crate engine. You get a fully assembled/tested engine, warranty(!!!!), and proven numbers. On top of that, you have your original engine for backup purposes, or for selling to help offset the price of the new engine. In the long run, it's usually a few bucks cheaper just to buy a new crate engine in the config that you want. Pull the old engine out, drop the new one in, and roll!!!
I got my ZZ4 from Scoggins-Dickey. I woulda got the ZZ430, but at the time, it was still a limited production, specialty engine that was almost 2x the cost of the ZZ4.