1980 Performance Mods

VetteManiac · 11-21-02, 11:18 PM

What should I do to increase the horsepower in my 1980 L-48? I have dual flowmaster exhaust, an edelbrock carberator, and an edelbrock air filter.

AKRAY4PLAY · 11-22-02, 02:34 AM

sounds like the biggest bang for your buck would be a cam swap. then i would look to heads or compression ratio next. you already have the other main component, EXHAUST! it all depends on how much you would like out of the motor. assuming your lower end is in good shape, a cam and heads will help the flow numbers and not really break the bank. if the lower end is high milage and/or questionable then i would lean to a new motor.

VetteManiac · 11-22-02, 01:58 PM

Well my car is a daily driver, with 93k miles. I also have a small budget.

AKRAY4PLAY · 11-22-02, 03:57 PM

if you are comfortable with a wrench, a cam swap will cost about $200. most cams are $100 to $150 and it will cost another $50 or so odds and ends. if someone else does the job, it may run $500-$800 with shop time. most shops will give you a quote to better balance your budget before the job. doing the job yourself is not that big of a deal, other guys on the forum and myself will be happy to walk you through the whole job. you will also want to do a compression test on all cylinders before you decide. if there is any more than 30 pounds difference between any cylinder, you have a lower-end problem. let us know what you would like to do, Brian

VetteManiac · 11-22-02, 07:46 PM

I'm not too great with a wrench, I haven't had much experience. (I'm only 17) But my dad knows a good deal. He used to have a '69. I could afford to do that myself, but maybe not have someone else do it. I don't know how to do a compression test though.

VetteManiac · 11-22-02, 07:48 PM

Oh, and could you tell me more about cams? Sites that have them for sale maybe. Stuff like that. Thanks.

AKRAY4PLAY · 11-23-02, 05:25 PM

compression tests are simple. the tool is about $30 and worth every penny. you will need to pull all your spark plugs, it helps to keep them in order of the way they came out of the engine. this way you can tell how the engine is running, from the color of the plugs and if they have any types of build-up on them. any service manual will have a page that shows spark plugs with different engine problems. reading the plugs in combination with a compression test give a very good overall picture of the condition of how the motor is running. sorry, back to the compression test. then all you have to do is screw the test hose into the plug hole and connect the pressure guage. crank the motor over a few times, no more than five should be needed, three is the norm i use. 150 psi is the factory standard, with no less than 20 psi difference between any cylinder. so, if you have a 30 psi difference, something is wrong with the motor. usually you will see blue smoke out the tail pipes if there is a problem with the motor. small blocks will run even though they are way out of spec, there are just that good. but they will not run strong if out of spec. if you have good compression then go for the cam swap, if not run it the way it is until you can afford a rebuild or crate motor. as for cams, Crower had a great website and the guys on the phone were very helpfull, Edelbrock, Crane, Holley, Summit Racing, Etc. all make cams and have info on there sites as well. look at any Super Chevy magazine or similar and they will have adds for all types of cam manufacturers. when picking a cam, talk with a few different places and let them know what you have and what you want to do with it. then make them explain why you should buy their product. best of luck, Brian

VetteManiac · 11-23-02, 09:43 PM

Thanks a lot for all of your help, Brian.
-Kyle

11-24-02, 12:08 AM

Kyle,

AKRAY4PLAY has the right idea. I've seen Vette's with high miles like yours pick up 40hp or more just by a tune-up. Once you got the basics covered a few parts could wake up that old L48. Get rid of those 76cc heads and go with a set of aluminum 64cc cambered heads. For the price you can't beat today's aluminum aftermarket heads. A good set of Trickflow 23 degree heads from Summit @ $899.00 could add about 100hp or more. I would try this first with the stock cam and see what you think. But be warned Horse Power is an addiction! You can get carried away very quickly.

http://www.holley.com/HiOctn/ProdLin...K/300-503.html

Holley & Edelbrock make complete matched kits with Intake, Heads, Cam and gaskets for less than $1500.00. Both companies have worked the bugs out of these kits and are a true bolt on and go setup. Good luck to ya buddy!

MoeJr · 11-24-02, 01:03 AM

Summit Racing sells cam kits under their name for $80. They come with the cam and valve lifters. Pick up a double roller timing chain and gears and for under 200 bucks you're on your way. The Cam kit I would suggest is Summit Part #SUM-K1102 or 1103. Specs are: 1102=204/214 Duration@.050 Lift with Lift being .420/.442 and Lobe Seperation is 112. 1103=214/224 Duration@.050 Lift with Lift being .442/.465 and Lobe Seperation is 112.

The 1103 cam will give you more HP at the cost of some low end torque. Bein this is a daily driver I would rather have more torque than HP. With that said I would get the 1102 kit. I used it in an 80 Z28 for a customer and he loves it. The 80 Z motor is the same as your L48. Just my .02

VetteManiac · 11-24-02, 01:09 AM

Thanks for the info guys. I know the 80 Z motor is exactly the same, because it is what is actually in my car.

Stallion · 11-24-02, 11:48 AM

>> Get rid of those 76cc heads and go with a set of aluminum 64cc cambered heads. <<

I don't understand, why would he want to go with smaller heads? Wouldn't you have to buy heads to fit the valves (intake and exaust)? How does that mod work? Thanks.

11-24-02, 01:05 PM

Stallion,

It would be a head swap with new valves. The 80 L48 motor only had around 8.5:1 compression ratio. 1. This limits how big the camshaft could be. 2. The L48 heads flow numbers just don’t compare to the new aftermarket heads today.

If you stepped up to a 64cc combustion chamber with a Felpro 1010 gasket and considering that the motor has not been decked the compression ratio would go from 8.5:1 to around 10:1. The compression ratio increase by itself would be a 30-50 Horse Power improvement. Add the larger valve sizes, better flow characteristics, new combustion chamber design technology and a matched camshaft 100+ horse power could easily be achieved.

MoeJr · 11-24-02, 01:49 PM

Being that Vettemaniac has a small budget I think heads are gonna be a bit out of reach unfortunately. At 10:1 CR he would hafta go with Aluminum as Iron heads and 10:1 CR is very difficult to tune for the street and have no detonation. I think his best bet is still a cam change. Just me .02.

11-24-02, 03:31 PM

Moe Jr.,

You’re probably right but remember with 95000+ miles the valve springs and seats are probably worn. With only 8.5:1 compression that hurts. Also for a 17 year old a head change would be allot easier than a cam change. The bottom end should be ok if the oil changes were done and the compression test checks out ok. Another cheap way out could be a Felpro #1094 Chevy-1955-96 262-350, steel embossed shim, @ .015 in. compressed thickness; 4.100" bore - $19.05 and lap / clean all the Valves in his heads and keep his stock cam. That should be good for at least a 20% HP improvement. I remember what it was like to be 17. It took 2 years for me to re-build my 68 Charger’s 383, but it can be done...