can i change my cam in my 73 250hp. engine to make more low end torque ? if so what ?

 

You can simply advance the stock cam 4 degrees for more low end .

 

Advancing your cam timing will help torque. Replacing the cam will help more.

 

I think that advancing the timing was not the answer you were looking for since you asked about a cam change. Assuming that the engine is all stock (heads, intake, and cam), I have asked the same question with my 78 L-82 which is internally all stock but externally have a Holley 4175, no emissions at all (EGR Valve, cat, heat riser valve in the exhaust, AIR pump etc) along with Shorty headers, 2.5 inch true duals, and Monza turbo mufflers. These changes have made a BIG difference in the HP but since the L-82 cam is a mid to high rpm cam, my engine lacks low end torque as well. Most people on the forum have suggested changing the heads and intake but I do not want to swap out the smog heads for aftermarket ones since the engine is all original with 65,000 miles on it. Just an FYI that a bone stock L-82 tested by Super Chevy magazine produced Dyno numbers of 313 Gross HP (net is 250) and torque of 355 ft Lbs, which really is not bad and as I have said repeatedly not far at all from the "mighty" LT-1 of 370/350/330 HP Gross! A proper cam change will get the L-82 into the LT-1 territory easily with stock heads but will not produce BIG HP gains but a noticeable gain though. Here is part of the article for the nay sayers:

"Loyal readers will remember that the low-compression L82 was equipped with 882 heads, L46 hydraulic cam (0.450/0.460 lift, 222 duration) and an induction system consisting of a cast-iron intake and Q-Jet carb. The Q-Jet was actually less of a hindrance than you might suspect as the 750 cfm rating was more than adequate for the needs of the 250hp L82. In stock trim on our dyno, the 9.0:1 L82 produced 313 flywheel (gross) horsepower at 5,500 rpm and 355 lb-ft of torque at 3,800 rpm. The engine produced adequate torque relative to the horsepower rating, but it wasn't exactly what you'd describe as earth-shattering. Replacing the stock 882 iron heads with 200cc RHS aluminum heads, an XE274H hydraulic flat-tappet cam and Pro Comp dual-plane, aluminum intake resulted in some serious power. Fed by a Holley 750 HP series carb (we should have tried a test with the stock Q-Jet-sorry), the upgraded L82 produced 414 hp at a slightly higher 5,900 rpm and 415 lb-ft of torque at 4,100 rpm. The upgrades to the L82 improved power throughout the rev range, from 3,000 rpm all the way to 6,500. The gains would be even greater on a milder small-block (from, say a truck) since the stock cam timing would be even milder than the L46 cam used in the L82."

Changing the heads and cam will produce BIG HP on the L-82 (new heads, Cam and intake PRODUCED 100 HP!!) but a cam/intake change only should produce respectable improvements as well (probably 30-40 HP). I am looking at the Comp Cams 268 for my L-82 but i am sure that there are many others like Crane. I would talk to them directly. Hope that helps!

 

If you look at my signature, you will see what I've done to my '74 L-82. The Comp Cam XE268H is a nice compromise as it has a slightly rough idle but you can still lug it down in 3rd gear and it will pull smoothly from there. I've been very happy with the setup. I'm running the factory AC and don't have any vacuum problems. Regarding the torque; when running thru the gears, this thing pulls great! I've had the cam in the car since 1997 and as I'm now 70 years old, I don't run it as hard as I used too Prior to the XE268 I had a Comp Cam 280 Magnum in the engine and it was too much cam for the setup. Marginal on vacuum, wouldn't idle under 1200 and in town when driving around 20-25 mph, I had to use 1st gear. Pulled the cam after one summer. It sounded tremendous; at idle it sounded like an 800 HP Sprint car motor---but that's another story!

Mike

 

the L-82 is an excellent engine! most people who trash it don't know what they are talking about! it is essentially an LT-1 with a different cam & intake . pistons in a 70 were different. i freed up the exhaust changed intake&Carb pocket ported the heads advanced the cam and it screamed. way underrated engine.

 

What exactly is a pocket port of the heads and did you do it yourself? What intake do you use?

 

thanks so much for the info. this engine is in my 72 . the cam has been changed by the previous owner.it will barely idle when in gear,and has no ! low end power ! i am contimplating replacing it with the stock cam . any extra input would be greatly appreciated !

 

Anything else you leave out, are the heads, intake, distributor and carb stock?

 

pocket porting involves smoothing the bowl under the valve seat it can be done with a small die grinder practice on a junk head. i used an LT-1 intake but an r.p.m. air gap is probably better now.

 

Thanx. I have a friend who could probably do the pocket porting. My understanding is the RPM air gap will not fit under the hood of 78 with the OEM air cleaner housing so I don't think that is an option. Is the OEM L-82 aluminum intake costing me enough HP that I should change to an aftermarket one?

 

yes,not the best intake