Lt 1 heads
Thread Starter
Intermediate
Joined: Jan 2005
Posts: 32
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From: Hurst TX
Lt 1 heads
I have an opportunity to get a pair of LT-1 heads (casting # 3991492). Will these heads work with a 1974 L 48 bottom that has been rebuilt? Will the stock crank stand up to the load ?
Team Owner
Joined: Aug 2006
Posts: 24,125
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From: Columbia Missouri
You won't see any gains from those heads without a better cam and higher compression. Also, exhaust would make a huge difference.
Racer
Joined: Nov 2007
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From: coon rapids mn
yes these heads will wake up your engine how much is any body's guess they should raise your compression and outflow your l48 heads a cam would help with the head swap to take advantage of the compression and improved flow those heads where some of the best factory casting as far as performance goes in the 60's and 70's
Melting Slicks
Joined: Feb 2006
Posts: 3,428
Likes: 5
From: Japan
Your stock L48 bottom end won't suffer any ill effects from simply attaching a pair of LT1 heads, but if you want to start making real power by installing a racy cam, etc. it would be advisable to at a minimum get some better rod bolts and forged pistons.
Thread Starter
Intermediate
Joined: Jan 2005
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From: Hurst TX
Right on ! Chevy High Performance April 91 issue had a combination of 64cc heads (GM #186) Sealed Power forged pistons, stock rods, cast crank, Comp cams 268, Victor jr intake into 1 3/4 in. headers. Made 383 HP@5250 404 max torque@4100 10.5:1 Comp ratio
Thread Starter
Intermediate
Joined: Jan 2005
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From: Hurst TX
Do you happen to know the specifics on the L 82 cam and maybe a GM part #?
Buy the way I have always enjoyed reading your comments to a variety of post.
Thread Starter
Intermediate
Joined: Jan 2005
Posts: 32
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From: Hurst TX
yes these heads will wake up your engine how much is any body's guess they should raise your compression and outflow your l48 heads a cam would help with the head swap to take advantage of the compression and improved flow those heads where some of the best factory casting as far as performance goes in the 60's and 70's
One of the best heads for 60's and 70's from what I have been able to find I agree.
I have wanted to use factory castings as opposed to aftermarket.
One of the other unanswered questions I have is will my Q-jet with some reworking work ?
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Race Director
Joined: May 2005
Posts: 10,674
Likes: 122
From: Millington Illinois
St. Jude Donor '08-'09
Stock L82 cam is .450 int lift and .460 ex lift. intake duration is 346 ex duration is 360. Believe these duration numbers are actual not at .050 lift. GM part # is 3896962 for the L82 cam. They used this cam from 1973 through the 1980 model year on all L82. Pretty nice piece and mild ramp rates compared to modern cam grinds, low maintainance, durable, good power. I am pretty sure they have a 114 LSA which gives you a broad, flat torque curve. Great street cam for your mild build.
Edit: Information from Corvette By The Numbers.
Last edited by 63mako; May 1, 2008 at 12:15 AM.
Melting Slicks
Joined: Oct 2001
Posts: 2,064
Likes: 1,382
From: Halifax, Nova Scotia, Canada
GM PART # 3896962
CATEGORY: Engine Camshaft
PACK QTY: 1
CORE CHARGE: $0.00
GM LIST: $195.71
OUR PRICE: $142.48
DESCRIPTION: CAMS- 350
Hydraulic Flat Tappet
This hydraulic flat tappet is used on the 68-81 L-46 and L-82 Corvette. The duration at lash point in degrees (intake/exhaust) is 312/312; duration at .050" tappet lift (intake/exhaust) is 222/222 and maximum lift with 1.5:1 rocker ratio (intake/exhaust) is 450/460. Valve lash is zero/zero and lobe centerline is 114 degrees.
Race Director
Joined: May 2005
Posts: 10,674
Likes: 122
From: Millington Illinois
St. Jude Donor '08-'09
You are right but he has access to these, they flow well, and maintain stock apperance. There are a lot of newer grind cams but also a lot of flat tappet cam failures with the modern ramp rates. I know about the changes in the modern oils but fast ramps are a big factor as well. All the cam manufacturers now are going with the fast ramps to squeeze every possible hp out of build to be able to advertise "our cam produces X hp on this build" The L82 GM cam is a proven workhorse that makes good power and will probably run on 91 octane with his iron head build with little maintainance issues. His intake and carb will bolt right up, it will look bone stock and the stock bottom end will handle it with no problems. Quadrajet will work fine with this, Might need to tweek it a little. Sure there are heads that flow better, sure there are cams that make more power. But there is always someone faster.
Last edited by 63mako; May 1, 2008 at 11:42 PM.
