Here's a good question for everybody

[WONKABOY]

Would it be possible just to have a mild bolt in cam installed without touching the heads so i can get some more power from the start, i'm used to a 300 hp 94 vette that i had four 7 years , if you had one than you know what i'm missing, but i do love this style Corvette just as much , sometimes even better! Another thing my CHECK ENGINE does not come on anymore , it slowly went away and i forgot about it, at the end it would come on if i was at a long stand still , even at the gas station filling up, but no more thank god, supposedly it was fixed , but every now and then you would see it , it has been about 2 months and NO MORE!!! I know by the service records within 10 years only 2,000 miles were put on, now i'm driving the **** out of it, the only thing left besides the paint, is shocks, suspension work, and universals , other wise it run's fine and idle nice at the stop signs, i love pulling up next to a Mustang with my dyno max mufflers , sounds great , but i still need a good pull from a stop, any suggestions ?

 

[GerryLP]

Would it be possible just to have a mild bolt in cam installed without touching the heads so i can get some more power from the start, i'm used to a 300 hp 94 vette that i had four 7 years , if you had one than you know what i'm missing, but i do love this style Corvette just as much , sometimes even better! Another thing my CHECK ENGINE does not come on anymore , it slowly went away and i forgot about it, at the end it would come on if i was at a long stand still , even at the gas station filling up, but no more thank god, supposedly it was fixed , but every now and then you would see it , it has been about 2 months and NO MORE!!! I know by the service records within 10 years only 2,000 miles were put on, now i'm driving the **** out of it, the only thing left besides the paint, is shocks, suspension work, and universals , other wise it run's fine and idle nice at the stop signs, i love pulling up next to a Mustang with my dyno max mufflers , sounds great , but i still need a good pull from a stop, any suggestions ?

Wonka,

The compression ratio of 8.2 on an L81 won't help a cam replacement give you a hope for 5 horsepower gain. This issue has been discussed at lenght here, and you can probably spend a couple of hours reading through them, but the fact is that there is no majic formula.

Any change in components will eventually require an additional change on another component, but for starters, you could install a pair of 64 CC's Heads. On average, the 10 - 12 cc' reduction on chamber size should give you a 9:1 boost on compression ratio (just remember that this is only a ballpark figure -you can't know for real unless measuring all the related components).

Anywho, this might help you gain a bit of that mising seat-of-the-pants feeling.

GerryLP:cool

 

[WONKABOY]

Wonka,

The compression ratio of 8.2 on an L81 won't help a cam replacement give you a hope for 5 horsepower gain. This issue has been discussed at lenght here, and you can probably spend a couple of hours reading through them, but the fact is that there is no majic formula.

Any change in components will eventually require an additional change on another component, but for starters, you could install a pair of 64 CC's Heads. On average, the 10 - 12 cc' reduction on chamber size should give you a 9:1 boost on compression ratio (just remember that this is only a ballpark figure -you can't know for real unless measuring all the related components).

Anywho, this might help you gain a bit of that mising seat-of-the-pants feeling.

GerryLP:cool

Hey thanks for your feedback, i guess that ends that , i'll stick with it stock!!

 

[21again]

After this summer is over I'll be pulling the L81 motor out of mine and try and figure out what to do with it, or change - if anything. It's leaking oil like crazy but not "using" any at all. Sooo, do I just replace all the gaskets and call it fine? How much further should I go refreshing the motor? New cam, (stock?). Lifters? Rods? New Exhaust Manifolds (The stock "stainless steel" ones are leaking too, cracked?). Do I pull the computer and replace with a standard distributer and "normal" quadrajet? It's like what GerryLP said "Any change in components will eventually require an additional change on another component". This really is the most profound statement I've read in this forum for a long time. You start to "alter" the original design and it really does just go on and on and on with adjustments. The motor is 190 HP on a good day going down hill with the wind. BUT, the look of this 'vette is UNMATCHED. No matter what the age of the person - heads turn.

 

[bill81vette]

It's leaking oil like crazy but not "using" any at all. Sooo, do I just replace all the gaskets and call it fine?

you might want to check around the valve covers,somebody at one point took mine off and used the same old gaskets (BUBBA???) with silicone to try to reseal them :ugh ! I did remove and replace them this past winter.at any rate I also know that my rear main is leaking a little,Maybe next winter when If get ambitous and pull the tranny to freshen it up!
good luck!!

 

[Tom Bryant]

Your check engine light should come on when the key is turned to the on position as a system check. Then it should go out when you start the engine.

There are some cams designed for low compression ratios that have very little overlap and rapid ramp rates that close the valves fast and early. This increases cylinder pressure making your engine "think" it has a higher compression ratio. All of the major cam companies sell these as well as GM performance. GM Performance cam kits are manufactured by Crane. Call Crane or Comp Cams tech line and tell them what you have. They wiil recommend a cam that will be matched to your engine. I see that several of the GM cams are compatible with computors and designed for '81-'87 cars and light trucks with stock rear end ratios. Don't expect big block power with just a cam change but you should be able to feel a boost in the seat of the pants off idle and in the lower to mid range rpm ranges. With your stock exhaust system you won't get much improvement in higher rpm power. If you want an across the entire rpm range power increase start with a good performance real dual exhaust system then go to work on the engine. Too big of a cam will do nothing in a stock L81. May even slow the car down and make it feel sluggish off idle. Match the cam to what you have not what you think that you may do later. You will be better off changing cams again if you do heads, headers, intake/carb later on.
One thing to watch when increasing cylinder pressure is pre-ignitiion. You may need to do some distributor tuning if you experience any pinging.

 

[WONKABOY]

CAM

Your check engine light should come on when the key is turned to the on position as a system check. Then it should go out when you start the engine.

There are some cams designed for low compression ratios that have very little overlap and rapid ramp rates that close the valves fast and early. This increases cylinder pressure making your engine "think" it has a higher compression ratio. All of the major cam companies sell these as well as GM performance. GM Performance cam kits are manufactured by Crane. Call Crane or Comp Cams tech line and tell them what you have. They wiil recommend a cam that will be matched to your engine. I see that several of the GM cams are compatible with computors and designed for '81-'87 cars and light trucks with stock rear end ratios. Don't expect big block power with just a cam change but you should be able to feel a boost in the seat of the pants off idle and in the lower to mid range rpm ranges. With your stock exhaust system you won't get much improvement in higher rpm power. If you want an across the entire rpm range power increase start with a good performance real dual exhaust system then go to work on the engine. Too big of a cam will do nothing in a stock L81. May even slow the car down and make it feel sluggish off idle. Match the cam to what you have not what you think that you may do later. You will be better off changing cams again if you do heads, headers, intake/carb later on.
One thing to watch when increasing cylinder pressure is pre-ignitiion. You may need to do some distributor tuning if you experience any pinging.

THANKS FOR THE INFO...... RICK