Guys,

I'm currently undertaking my first ever engine work.

I have a fully standard 1979 L48 motor. I am currently adding the following parts:

Edelbrock Performer rpm Intake
Holley 670cfm Street Avenger Carb
Cast Heads from an earlier year 1.94/1.50 valves but smaller combustion chambers - 64cc
Roller Rocker arms
Comp Cams 268H cam + lifters
Cloyes true double roller timing chain

and various other cosmetic mods

Any idea what this kind of setup should produce in terms of horsepower and torque.

I will be keeping the standard cast exhaust manifolds for now which run into a 2 1/2" stainless 2-1-2 exhaust system.

That Edelbrock Performer RPM intake is higher than stock. You may have to get a drop down type air cleaner due to clearance problems. I put an Edelbrock Performer (not the RPM) in my '78 L82, and while there are no clearance issues (Edelbrock says the standard Performer will cause no clearance problems), it does put my stock air cleaner assembly into the underhood insulation.

My guess would roughly be 250+/- at the flywheel. My '69 350 from SS Chevelle was rated at 300hp, it had 64cc chambers, 1.94/1.5 valves, but had flat top(w/valve reliefs), and had a spec'ed compression of 10.25:1 . 64cc heads on your L48 should raise you compression to around 9:1 I believe. I would consider Vortec heads if budget heads are what are looking for. I still have my '69 350, or atleast all the compoants to assemble it, I had considered using the heads on my Vette, but 1.There are no accessorie holes in the front of the heads, 2.They don't have hardend exhaust seats for running unleaded gas, 3.Vortec heads flow better out of the box than older 64cc heads without dumping $$$ into machine work. If you keep your eyes open, you can find used ones cheap, I just missed a set in the local trading paper w/350 block for $100, and you can get new ones for under $500 complete pair.

I would add flattop pistons to the list. Stock L-48's have dished pistons and 76cc heads which GM states 8.5 comp. Reality is that because of the deck height they are closer to 8. Roller rockers are not needed for your setup so you could save money going with roller tips and use the $ else where.

Thanks for the replies guys.

I will not be changing pistons as I am unable to get the engine out, lack of room and facilities.

If I were to get the engine out it would be a different story, 383!!

As long as I get a noticable difference in torque and general drivability I will be happy.

I am based in the UK but have ordered most of my parts from the States so I'm just awaiting the parcels!

In time I plan to uprate the tranny, torque convertor etc.

I'm learning more and more every day.

I would also consider an MSD ignition. I'm running an 82 4 bolt main block with a steel crank and forged 11.0-1 barrel cut pistons, linked with forged rods. I have a set of mid 70's or early 80's heads with the 2.02" intake and 1.94" exhaust valves. I also used an Isky .526" lift cam with a gear drive and crane cams 1.6 roller rockers. I used the edelbrock victor jr intake and a 750 double pumper with the MSD Billit Distributor and MSD 6 AL box to top it all off. I'm lookin at around 500 horse from the motor, linked to a street/strip turbo 350, 3000 stall converter and 3.70 gears.

|UPDATED|11/10/2003 10:23:50 AM|/UPDATED|

I rebuilt my motor using some similar parts to what you have listed.
Holley 750 Vaccum Secondary
Comp 268 Extreme Camshaft (higher lift ratios)
new pistons and rods (10:1 compression with the 64cc heads)
Vortec Heads (64cc)
Performer Intake
Hooker full length headers

When I first rebuilt the motor, I used the stock heads. I was not that impressed with the combination. I then changed over to the Vortec heads. This raised my compression and made a big difference. I was still using the stock ram exhaust manifolds though. I recently installed a set of 1 7/8" headers. Now my engine is breathing alot better. I copied a build up from one of the Chevy magazines. The combination is suppose to be making around 360 to 375 hp with about 390 lbs of torque. I could not afford to install everything at once, so I made a few changes along the way. Next, I will probably change the torque converter.
Good Luck.

Hi Guys,
I have an 80 L48, I recently put on an edelbrock 2101 aluminum performer intake, an edelbrock 600 cfm carb, and true dual exhaust from mid america. Everything fits under the hood without a problem. I notice a boost in low end torque, but the upper range is still lacking, I would love to put better flowing heads on, I saw that everyone is recommmending vortec heads, and the price is right, but will they really bolt up to the 1980 motor, and the stock exhaust manifolds without any additonal things?

If i'm not mistaken, the only difference is on the intake side of the heads, so the heads will bolt directly to the block with no problems, and the exhaust manifolds should work fine.

The Vortec heads will need a different intake manifold. The bolt pattern/angle is different.