gil7247

I recently acquired a very well taken care of 1980 with 75,000 actual miles. I am only the third owner and received a hand written journal from the first owner of all work that was ever done on the car and what date it was done. Included in this was a complete engine overhaul to the stock L48. They kept the engine stock except for a mild flat tappet cam, Edelbrock Performer intake, Holley 650 vac sec and headers. This was done at 70000 miles and it runs great and carries great oil pressure. I would like to add just a little more pep with the addition of a good set of Alum, heads and a more aggressive roller cam and roller rockers. I am looking for advice on cam and head selection and I am willing to change intakes as long as I can stay away hood clearance issues. I want to keep good vacume and street manners.
Also I am seeking advice on what stall rpm of torque converter to go to with this upgrade.
I know I could just buy a crate engine, but this engine is so tight and runs so well it seems a waste to have it sit on an engine stand for the rest of its life.
Any advice will be greatly appreciated. GIL

Jebbysan

I like Dart heads....so my recommendation would be a pair of Dart 180 Pro 1 Platinums (NOT the SHP).
Here is my cam recommendation......
https://howardscams.com/i-24079290-h...ifter-kit.html

Lift: .495 / .500, Duration @ .050: 217 / 225, Centerline: 104, Noticeable idle, Broad low to mid-range power band, Needs 2000+ stall converter.

A 2500-2800 Hughes converter would work well here.........

The intake could stand to be upgraded to a Air Gap style.......Dart make a nice one of those too that is as good if not better than the Edelbrock but you will have to check hood clearance......68-72 stock hood will not support it, but the 73 on will..........
Keep the 650......but make sure you jet it and CURVE the distributor....

Jebby



Jebby

gil7247

The numbers for the cam that's in there according to the records I have : Wolverine Blue Racer Lift: .450 /.460 Duration @ .050 224 / 224.

mrvette

Only thing I would consider is a set of L98 aluminum heads, and DPFI for the fuel economy hell get a complete top end from an L98 ......to keep life easy, use a speed density computer GM 1227730 it's essentially what I did to my L48 in my '72......

jb78L-82

That cam ^^^ is essentially an L-82 cam with .450/.460 224 duration (L-82 duration with the same lift is 222) BUT the L-82 had 9:1 compression versus 8.2-8.5:1 (with the bigger valved 882 heads) with the base motor L-48 which will kill power along with L-48 small valve heads. Jebny's cam recommendation with good aluminum heads for flow and to raise compression will really wake the motor up.

mobird

Ok this is very important on your L48. When the engine was rebuilt, did they upgrade the pistons to something higher compression? Or are they the stock pistons?

If they are the stock pistons (which it sounds like they are), MAKE SURE to get heads with a 64cc (or smaller if you can find it) chamber. The L48 only has about 8:1 compression, so going to a 64cc chamber from your stock 76cc chamber heads will get your compression up to close to 9:1. Also, use a .015 shim head gasket for another half point of compression (this should put you over 9:1).

Compression ratio is key to what camshaft you can run, a low compression motor is lazy and can't take advantage of a good camshaft.

gil7247

The pistons were the oem stock l48 ones. Thanks for the info

mobird

Ok cool, all is not lost! I am running stock dished pistons in my motor, along with Brodix IK200 heads (64cc chambers) and a shim head gasket which gets me about 9.4:1 compression if I remember right (I cc'ed my pistons when I had the motor apart, but I don't recall the exact dish size at the moment). Aftermarket pistons with a better design can give you better quench and a bit more compression, but when on a budget you work with what you have!

I paired that combo with a Lunati 268 flat tappet cam and it is a completely different motor. The L48 made like 180 hp stock. You can expect roughly double that with a cam and head swap if they are decent flowing heads.

You are probably ok keeping the performer intake with the power levels you will be at, you may be giving up 10 hp or so running it instead of the RPM, but then you have to mess with drop base air cleaner and such to make the hood shut so may not be worth the trade to you.