1978 L48

[SCOOTER]

Does anyone know how difficult it is, or if it's possible, to change a L48 into a L82 to get the extra 35hp? Thanks for any help.

[Duke W.]

Re: 1978 L48

Just install the L-82 cam. That's about 80 to 90 percent of the difference.

Duke

[Patrick H.]

Re: 1978 L48

Scoot, (we're supposed to use names here by the way, not "handles")

The difference came down to carb jetting, camshaft, intake and exhaust valve sizes (and springs as a result) and the use of aluminum intakes in some late 70's L-82's (not sure of 78) which were essentially mirror images of the L-48 cast iron intake.

For your money, a good performance distributor tune and Q-jet carb tune would get you a large part of those extra horses. To change the cam and valves just wouldn't be worth it in my opinion. Also, verify that your catalytic converter is in tip-top shape, and if it isn't you might consider a swap to a high performance replacement.

Patrick

[Patrick H.]

Re: 1978 L48

And if he does decide to go that far, advance it 4 degrees for more SOTP feel and a lot more fun.

Of course, the odds of any of us doing ONLY a cam swap without playing with the rest of the motor? Pretty low is my guess.

PH

[Patrick H.]

addendum

The L-82 also had forged pistons vs. cast, and better rods, but of course these had little to do with the actual performance and/or horsepower.

PH

[Duke W.]

Re: addendum

I think the L-82 might have had a dual schnorkel air clearner with two heat stoves, so this or a open element air cleaner would help.

Also, the single converter was a real restriction. A modern honeycomb type converter would be helpful, but backdating the exhaust to a full 2.5 inch system would really wake up either a L-48 or L-82.

Duke

[Patrick H.]

Re: addendum

Duke,

Swapping the manifolds to a true 2.5 wouldn't be tough on a 78 given its style of alternator mounting, but I don't know if anyone anywhere makes a 2.5 inch Y-pipe for them. Lacking that, the L-82 might have had the 2 inch-to-2.5 inch change just after the manifolds. I'd have to look that one up. I suppose a true 2.5 inch Y-pipe could be custom made without a whole lot of work, though.

Patrick

[Duke W.]

Re: addendum

I think you missed my point. There would be a big improvement in mid range and top end power by backdating the exhaust to '74 - true dual exhaust - no Y-pipes.

Of course, if you live in an area that requires emission testing I would recommend you leave the exhaust alone except for a modern monolithic converter.

Duke

[Chas Kingston]

[Marvin Barton]

Re: 1978 L48

Scooter-

True dual exhaust is, far and away, the best bang for the buck on 78-82 whether L-82 or L-48 if you don't have originality or emissions reservations. Some reports are a 25-40 hp increase! Differences are: L-82 has 4 bolt mains, forged pistons, greenstripe rods, steel crankshaft, 2.02/1.60 valves, hotter cam, different timing/advance curve in the HEI, larger jet/rod and power piston spring in the carb, and aluminum intake and magnesium(painted black)valve covers. In 78 the L-82 had a dual snorkle air intake which actually functions better than open air breathers due to getting cooler air into the carb. The L-82 cam makes more power at higher rpm so if you're a low-end torque lover get a different camshaft. Good luck.

Marv-

[Patrick H.]

Re: addendum

Duke,

I figured that might be a part of your point, but of course wasn't a part of the true 1978 configuration. As "any" removal of the cat is illegal, I thought it best to avoid mentioning it and mentioned the high flow convertor instead. Modifying to a 2.5 inch pre-cat, while not following the letter of the law, sure couldn't hurt.

Patrick