Timing Chain Replacement. Cam too?
Thread Starter
Race Director
Joined: Dec 2000
Posts: 10,896
Likes: 2
From: CO
Timing Chain Replacement. Cam too?
I am going to be replacing the timing chain soon and wondered if a cam swap would be a good idea or not? Its a bone stock 75. I dont know much about cams except the general idea of how they work.
Would it make much difference in my L48? What cams would work well? How much chance is there of messing up the motor during the install?
Would it make much difference in my L48? What cams would work well? How much chance is there of messing up the motor during the install?
Drifting
Joined: Sep 2004
Posts: 1,532
Likes: 4
From: Fairview Heights Illinois, near Saint Louis MO, STL C3 Shark
How much time you got? Timing chain can be done without too much effort. Changing the cam is a different story. If you've got the time, then go for it, but unless you pull the engine, you'll have to definately remove the radiator, and perhaps the hood in order to slide the old cam out, new one in. 
Team Owner
Joined: Feb 2005
Posts: 32,519
Likes: 1
From: central America
St. Jude Donor '08-'09
When i did the timing chain on my 72 a few years back, it took about 3 hours just to do the chain and gears.
Before doing a cam change you should ask yourself: Am I going to do other performance upgrades in this car? Should I wait to do the cam so that it better matches the rest of the work that I am planning? I would think about that rather then just throwing an RV cam in a car like a corvette.
just my 2 cents.
trw
Before doing a cam change you should ask yourself: Am I going to do other performance upgrades in this car? Should I wait to do the cam so that it better matches the rest of the work that I am planning? I would think about that rather then just throwing an RV cam in a car like a corvette.
just my 2 cents.
trw
Burning Brakes
Joined: Apr 2003
Posts: 844
Likes: 0
From: Central KY
Originally Posted by flood
I am going to be replacing the timing chain soon and wondered if a cam swap would be a good idea or not? Its a bone stock 75. I dont know much about cams except the general idea of how they work.
Would it make much difference in my L48? What cams would work well? How much chance is there of messing up the motor during the install?
Would it make much difference in my L48? What cams would work well? How much chance is there of messing up the motor during the install?
Melting Slicks
Joined: Jan 2004
Posts: 2,672
Likes: 1
From: New Cumberland PA
If you're looking for a few more ponies, then go ahead and do a cam change. It's a lot more involved than changing the timing components. The intake must come off to remove the old lifters and intall new ones. Changing lifters is not optional, it's required. If this is your first time, read up before taking on this job and have someone who can assist in the reassembly. Removing parts takes less knowledge than it does to install them correctly.
As for a cam, something in the order of the L-82 should work fine. I would think any cam with around 218* duration @ .050 lift would work decently and a valve lift of .450-.480. There are many choices to pick from.
As for a cam, something in the order of the L-82 should work fine. I would think any cam with around 218* duration @ .050 lift would work decently and a valve lift of .450-.480. There are many choices to pick from.
Pro
Joined: Mar 2001
Posts: 633
Likes: 1
From: Hamilton, ON, Canada
A cam change is definitely worthwhile. The stock cam is mediocre. Putting in a mild cam will change the character of the whole car- giving more pick-up and letting it rev higher. My first upgrade was called "Hot Street Beast", by Crane I think. It really wasn't too hot but improved the car a lot while still allowing for stop & go city driving. I've since moved on to even hotter things.
Race Director
Joined: Mar 1999
Posts: 10,258
Likes: 1
From: Calif.
Well, you're probably going to have to drop the oil pan to get the timing cover off. May want to remove it altogether so you can start fresh with a new gasket.
A full-on cam swap will see you draining the coolant, removing the distributor, carb, intake and radiator in addition. And the hood, too, if you want some clearance to work.
It's a medium-sized thrash but I figure you may as well get it all done at once. You should be able to have it all buttoned back up and running in a weekend or so, depending on your skill level and experience.
A full-on cam swap will see you draining the coolant, removing the distributor, carb, intake and radiator in addition. And the hood, too, if you want some clearance to work.
It's a medium-sized thrash but I figure you may as well get it all done at once. You should be able to have it all buttoned back up and running in a weekend or so, depending on your skill level and experience.
Burning Brakes
Joined: Apr 2004
Posts: 814
Likes: 2
From: WESTLAKE LA
Originally Posted by The Dude
Well, you're probably going to have to drop the oil pan to get the timing cover off. May want to remove it altogether so you can start fresh with a new gasket.
A full-on cam swap will see you draining the coolant, removing the distributor, carb, intake and radiator in addition. And the hood, too, if you want some clearance to work.
It's a medium-sized thrash but I figure you may as well get it all done at once. You should be able to have it all buttoned back up and running in a weekend or so, depending on your skill level and experience.
A full-on cam swap will see you draining the coolant, removing the distributor, carb, intake and radiator in addition. And the hood, too, if you want some clearance to work.
It's a medium-sized thrash but I figure you may as well get it all done at once. You should be able to have it all buttoned back up and running in a weekend or so, depending on your skill level and experience.
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Safety Car
Joined: Jun 2004
Posts: 4,652
Likes: 80
From: Lakeland Florida
If you go through the effort of taking everything off to replace the cam, wouldnt it be a good time to add new pushrods, rocker arms and an intake manifold?
It seems like if the engine is taken apart to that level, then do all the mods at one time.
kdf
It seems like if the engine is taken apart to that level, then do all the mods at one time.
kdf
Le Mans Master
Joined: Mar 2004
Posts: 7,493
Likes: 1,501
From: Little Rock AR
I would change the cam too as it is not that difficult and it would be effective. If all you do is freshen the engine up but not change the heads/pistons, you would like the Comp 268H cam. 
You would not like the L-82 cam with the lower compression L-48 engine. It would feel lazy and the stock "929" cam would probably work better for the stock L-48. The factory used the L-46/L-82 cam with 9:1 through 10.5:1 engines. Anything less would not be a good match.
The L-82 cam is great if you change the heads to 64cc's and run thin gaskets. I run actual 10.4 CR with that cam in my Vette. If it runs well at that compression, think about how it would run with 7.5-8:1 compression.
-Mark.
You would not like the L-82 cam with the lower compression L-48 engine. It would feel lazy and the stock "929" cam would probably work better for the stock L-48. The factory used the L-46/L-82 cam with 9:1 through 10.5:1 engines. Anything less would not be a good match.
The L-82 cam is great if you change the heads to 64cc's and run thin gaskets. I run actual 10.4 CR with that cam in my Vette. If it runs well at that compression, think about how it would run with 7.5-8:1 compression.
-Mark.
