Lt1 ?
Thread Starter
Instructor
Joined: Aug 2005
Posts: 212
Likes: 0
Lt1 ?
Yesterday I had my valvecovers off, and found the casting numbers for heads. : A3973487
I also found out that this is head from LT1.
Since I have a -69, it seems that I have an updated engine.
What is LT1?
350 GM Block
LT1 Heads
Edelbrock Performer intake.
71-72 Q-Jet.
HEI distributer
How can I find out about cam?
Any idea of hp with this?
Curious Rookie
. . . . . . . . . .
I also found out that this is head from LT1.
Since I have a -69, it seems that I have an updated engine.
What is LT1?
350 GM Block
LT1 Heads
Edelbrock Performer intake.
71-72 Q-Jet.
HEI distributer
How can I find out about cam?
Any idea of hp with this?
Curious Rookie
. . . . . . . . . .
Team Owner
Joined: Feb 2005
Posts: 32,519
Likes: 1
From: central America
St. Jude Donor '08-'09
The 70-72 LT-1 engine option was a way for GM to come out with an engine that could just about put out big block horsepower in a small block package (like the old fuelie days). The cam is solid with great lift and quite the duration. See this website for more info (http://www.geocities.com/MotorCity/D...00/cmspec.html)
However, just because you have the heads, doesn't necessarily mean you have the cam. How does this cam react? Does it pull like all get out after about 3500 rpm, or is this car pretty good off the line. You really can't know without pulling the cam, or getting the receipts that tell you what cam is in it. Does the previous owner know?
trw
Horsepower...the 70 LT-1 had 370hp, gross at the flywheel...with something like 11:1 compression. If you're running pump gas on an iron head, safe to assume under 10:1, could put you in the low 300's depending on what other mods you have.
However, just because you have the heads, doesn't necessarily mean you have the cam. How does this cam react? Does it pull like all get out after about 3500 rpm, or is this car pretty good off the line. You really can't know without pulling the cam, or getting the receipts that tell you what cam is in it. Does the previous owner know?
trw
Horsepower...the 70 LT-1 had 370hp, gross at the flywheel...with something like 11:1 compression. If you're running pump gas on an iron head, safe to assume under 10:1, could put you in the low 300's depending on what other mods you have.
Race Director
Joined: Dec 1999
Posts: 19,610
Likes: 778
From: Forked River NJ
The "487" head was also used on the standard Vette engine (L48) also. So just because you have this head does not mean it was on an LT1 motor. It could be off the L48 motor which was also used in many other Chevrolet cars. The LT1 heads did have the bigger valves though.
Racer
Joined: Sep 2004
Posts: 279
Likes: 0
From: Bellport NY
I believe the LT-1 heads are 487x. WHich is the 76cc chamber, 2.02 valves, 3/8 press-in studs and guide plates. The "x" is a 10cc increase intake (171?) volume. The 487 heads were supplied with either the 1.9 or 2.02 valves. The heads shoud have a 1971 date code. I have both versions of heads except 7/16 studs.
-mike
-mike
Melting Slicks
Joined: May 2001
Posts: 2,812
Likes: 4
From: Gig Harbor Wa
The 1970 L46 was an LT1 with different cam and intake. The heads and valves are the same. I am pretty sure the 69 350Hp engine is the same as the 1970 L46. If you have the 350Hp then you are supposed to have the LT1 heads.
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Racer
Joined: Sep 2004
Posts: 279
Likes: 0
From: Bellport NY
Originally Posted by mzmgb
I believe the LT-1 heads are 487x. WHich is the 76cc chamber, 2.02 valves, 3/8 press-in studs and guide plates. The "x" is a 10cc increase intake (171?) volume. The 487 heads were supplied with either the 1.9 or 2.02 valves. The heads shoud have a 1971 date code. I have both versions of heads except 7/16 studs.
-mike
-mike
Thread Starter
Instructor
Joined: Aug 2005
Posts: 212
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The heads are dated A1271 , which I believe is January 12th -1971.
from " MorTech" web-site:
from " MorTech" web-site:
3973487....71-72...350..........used on 71-72 350 LT1, 75cc chamber.
3973487X...71-72...350..........75cc chamber
3973487X...71-72...350..........75cc chamber
Racer
Joined: Sep 2004
Posts: 279
Likes: 0
From: Bellport NY
A little more generic. From:
http://www.stingray.nu/index2.htm?tips.htm
3973487 350 71-76 71-72 LT1, 75cc, 161/65cc port volumes
3973487X 350 71-72 75cc, larger intake ports
http://www.stingray.nu/index2.htm?tips.htm
3973487 350 71-76 71-72 LT1, 75cc, 161/65cc port volumes
3973487X 350 71-72 75cc, larger intake ports
Racer
Joined: Sep 2004
Posts: 279
Likes: 0
From: Bellport NY
According to "Corvette by the numbers" : 3973487 heads were used in 1971 & 72 only. The 1971 heads were used in the 330hp, LT1 Camaro and Corvettes (2.02 swirl polished valves). The 1971, 1.94 non-polished valves were used in 270hp versions. In 1972; 2.02 - 255hp, 1.94 - 175hp versions.
Of course, all the other components must be present to make up the LT1. Block, cam, carb, etc...
Of course, all the other components must be present to make up the LT1. Block, cam, carb, etc...
Le Mans Master
Joined: Dec 2003
Posts: 5,727
Likes: 38
From: Fremont CA
487X casting with screw in studs and pushrod guide plates. Throw them away and put some decent heads on the motor unless you are a NCRS type of owner. 25-40HP easy in better design cylinder heads.
Le Mans Master
Joined: Oct 2001
Posts: 5,943
Likes: 3
From: Wildwood IL
Originally Posted by Rock'n Old
How can I find out about cam?
Curious Rookie . . . . . . . . . .
Curious Rookie
. . . . . . . . . .Eddie
