72 LT 1 engine question???
Thread Starter
Safety Car
Joined: May 2008
Posts: 3,747
Likes: 713
From: Lafayette Louisiana
72 LT 1 engine question???
I got a 72 with a LT1 engine and have a question on the intake manifold.
Heads, block, carb all check out as original, but it has an Ederbrock Torker aluminum intake manifold instead of the original GM 3959594. I checked and the Ederbrock is a "single plane"? Was the GM a single plane? What is the advantage of a single plane? and finally why would anybody go to the trouble to just swap out the intake manifold? Are the aluminum intake manifold prone to corrode out? No headers, original exhaust manifold too.
Much thanks if anybody has any insights!
Heads, block, carb all check out as original, but it has an Ederbrock Torker aluminum intake manifold instead of the original GM 3959594. I checked and the Ederbrock is a "single plane"? Was the GM a single plane? What is the advantage of a single plane? and finally why would anybody go to the trouble to just swap out the intake manifold? Are the aluminum intake manifold prone to corrode out? No headers, original exhaust manifold too.
Much thanks if anybody has any insights!
Le Mans Master
Joined: Jun 2004
Posts: 6,231
Likes: 65
From: Seattle WA
St. Jude Donor '14
The stock LT-1 (not LT1) intake was a high-rise, dual-plane intake similar to the Performer RPM.
The Torker is a low-rise single-plane.
Dual-plane intakes provide better low-end torque and throttle response at the expense of top-end power. Single plance give up some low-end torque and throttle response to provide better top-end power. The Torker is a compromise to some extent - as a low-rise it tries to maintain better low-end torque while still providing high-end power. Overall, a high-rise dual-plane is the best choice for street engines making around 1-1.2 HP/CID.
I can't imagine why anyone would swap out the original intake; it's a decent street intake even today. I have a GMPP replacement item and an original that was installed on my '69 L-46. They're reasonably easy to find and not terribly expensive if condition and dates aren't important.
All IMHO, of course
The Torker is a low-rise single-plane.
Dual-plane intakes provide better low-end torque and throttle response at the expense of top-end power. Single plance give up some low-end torque and throttle response to provide better top-end power. The Torker is a compromise to some extent - as a low-rise it tries to maintain better low-end torque while still providing high-end power. Overall, a high-rise dual-plane is the best choice for street engines making around 1-1.2 HP/CID.
I can't imagine why anyone would swap out the original intake; it's a decent street intake even today. I have a GMPP replacement item and an original that was installed on my '69 L-46. They're reasonably easy to find and not terribly expensive if condition and dates aren't important.
All IMHO, of course
Race Director
Joined: May 2005
Posts: 10,674
Likes: 122
From: Millington Illinois
St. Jude Donor '08-'09
The stock LT-1 (not LT1) intake was a high-rise, dual-plane intake similar to the Performer RPM.
The Torker is a low-rise single-plane.
Dual-plane intakes provide better low-end torque and throttle response at the expense of top-end power. Single plance give up some low-end torque and throttle response to provide better top-end power. The Torker is a compromise to some extent - as a low-rise it tries to maintain better low-end torque while still providing high-end power. Overall, a high-rise dual-plane is the best choice for street engines making around 1-1.2 HP/CID.
I can't imagine why anyone would swap out the original intake; it's a decent street intake even today. I have a GMPP replacement item and an original that was installed on my '69 L-46. They're reasonably easy to find and not terribly expensive if condition and dates aren't important.
All IMHO, of course
The Torker is a low-rise single-plane.
Dual-plane intakes provide better low-end torque and throttle response at the expense of top-end power. Single plance give up some low-end torque and throttle response to provide better top-end power. The Torker is a compromise to some extent - as a low-rise it tries to maintain better low-end torque while still providing high-end power. Overall, a high-rise dual-plane is the best choice for street engines making around 1-1.2 HP/CID.
I can't imagine why anyone would swap out the original intake; it's a decent street intake even today. I have a GMPP replacement item and an original that was installed on my '69 L-46. They're reasonably easy to find and not terribly expensive if condition and dates aren't important.
All IMHO, of course
Le Mans Master
Joined: Dec 2003
Posts: 5,727
Likes: 38
From: Fremont CA
It wasn't uncommon to see swapped intakes on LT-1 motors (Camaros and Vettes.) Edelbrock claimed 20HP increase with Torker, I would say more like 10-12HP max with big low end torque loss and bad fuel distribution for an extra bonus.
I remeber reading about a 19HP increase for a 2plane Performer RPM over GM hi-rise, we observed around 6HP in the dyno testing of one of my motors way back when. I elected to run the GM hi-rise, Vette went 12.28@117MPH with a 1/2" spacer and stock plenum divider in it. That same Vette went 12.60's with ported iron exhaust manifolds. I used to enjoy the reactions of people checking the motor out in the staging lanes with the 12.75dial in on the windows, they were FREEKING at the stock looking motor (it had a lot of internal work done to it and a decent roller cam that ate lifters on a 5K mile basis.)
I remeber reading about a 19HP increase for a 2plane Performer RPM over GM hi-rise, we observed around 6HP in the dyno testing of one of my motors way back when. I elected to run the GM hi-rise, Vette went 12.28@117MPH with a 1/2" spacer and stock plenum divider in it. That same Vette went 12.60's with ported iron exhaust manifolds. I used to enjoy the reactions of people checking the motor out in the staging lanes with the 12.75dial in on the windows, they were FREEKING at the stock looking motor (it had a lot of internal work done to it and a decent roller cam that ate lifters on a 5K mile basis.)
Thread Starter
Safety Car
Joined: May 2008
Posts: 3,747
Likes: 713
From: Lafayette Louisiana
Ok and much thanks!
Ok and much thanks as this is quite informative! I am guessing somebody was looking to get more hp, the usual suspects
I am going to start looking for a GM 3959594, a quick check looked like they are expensive, and some brag that the thermostat hole is still good (think I got that right), does this corrode out?
I am going to start looking for a GM 3959594, a quick check looked like they are expensive, and some brag that the thermostat hole is still good (think I got that right), does this corrode out?
Team Owner
Joined: Jun 2000
Posts: 38,923
Likes: 1,481
From: Southbound
Cruise-In II Veteran
Are you considering having your car judged? If so, you will want a correct date for your manifold.
Can you contact the previous owner of your LT-1? He/she might have the original manifold pulled off for the Edelbrock.
Good luck with the hunt.
Burning Brakes
Joined: Jul 2009
Posts: 912
Likes: 47
From: Kansas City MO
Ok and much thanks as this is quite informative! I am guessing somebody was looking to get more hp, the usual suspects
I am going to start looking for a GM 3959594, a quick check looked like they are expensive, and some brag that the thermostat hole is still good (think I got that right), does this corrode out?
I am going to start looking for a GM 3959594, a quick check looked like they are expensive, and some brag that the thermostat hole is still good (think I got that right), does this corrode out?
Thread Starter
Safety Car
Joined: May 2008
Posts: 3,747
Likes: 713
From: Lafayette Louisiana
Thanks for the tip!
(Now there is capitalist idea, make available gold plated intake manifold bolts, likely would be the cheapest replacement part on the Corvette!)
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Race Director
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Le Mans Master
Joined: Dec 2003
Posts: 5,727
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From: Fremont CA
Late 71-72 LT-1 intakes have cylinder numbers cast into runners at port entry into head. BEWARE! that GM made a later crate motor aluminum intake that also had this feature but, also had a wide flange at the intake mounting face where the LT-1 intake had no flange extension above the intake port runners. That should help if your walking through a swap meet quickly scanning for a proper intake.
Le Mans Master
Joined: Jun 2004
Posts: 6,231
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From: Seattle WA
St. Jude Donor '14
As noted, I have one of the GMPP LT-1 style intakes (P/N 10185024) and I see them passed off all the time as a "factory" LT-1 intake. Note the differences in the pics below (fresh from the shop ) - especially how different the Winters "snowflake" is, the tapped boss at the front, no breather tube pad, bowtie on the back near the P/N....definitely need to be careful if you're looking for something NCRS-ready...
) - especially how different the Winters "snowflake" is, the tapped boss at the front, no breather tube pad, bowtie on the back near the P/N....definitely need to be careful if you're looking for something NCRS-ready...Last edited by billla; Jan 31, 2012 at 01:17 PM.
