L31R replacement engine?
Thread Starter
Racer
Joined: Mar 2012
Posts: 476
Likes: 37
From: Lynnwood WA
L31R replacement engine?
I have a 1979 C3 that until recently had an L98 with a 700R4 in it. The motor is gone. I still have a 700R4 trans, and all the stuff that bolts to the motor including a TPI setup that I like very much. I have been looking at crate motors, but have had trouble finding what I would like, (a 350 with at least 250hp, a roller cam, and be compatible with the TPI). What I am wondering is, would this motor, the way it comes LINK with the right base plate for my TPI, be appropriate? My objective is reliability, decent power (250+), decent millage (20+Hy), total expense under $3000.00.
Thanks for looking.
Zorro
Thanks for looking.
Zorro
Last edited by Zorro O; Jan 4, 2013 at 07:54 PM.
Melting Slicks
Joined: Apr 2006
Posts: 2,084
Likes: 14
From: Airdrie Alberta
Thread Starter
Racer
Joined: Mar 2012
Posts: 476
Likes: 37
From: Lynnwood WA
Melting Slicks
Joined: Dec 2009
Posts: 3,233
Likes: 657
From: Thunder Bay
Thread Starter
Racer
Joined: Mar 2012
Posts: 476
Likes: 37
From: Lynnwood WA
Thanks
Zorrio
Melting Slicks
Joined: Dec 2009
Posts: 3,233
Likes: 657
From: Thunder Bay
The cam in the crate motor is probably a pretty good match for the TPI. Lots of bottom end but will run out of steam pretty quick. Not what most of us are looking for when we build a Corvette motor, but it will work. If you decide later that you want to wake it up a bit, add more cam, a good four barrel and manifold, and a set of headers and you'll have a nice little motor.
Corvette Stories
The Best of Corvette for Corvette Enthusiasts
Top 10 Most Expensive Corvettes Ever Sold on Bring A Trailer
Brett Foote
10 Things Every Corvette Owner Needs (2026 Edition)
Michael S. Palmer
8 Most "Only Corvette Owners Understand" Quirks and Problems
Pouria Savadkouei
10 Reasons the C6 Z06 is Still A Performance Benchmark After 20 Years
Joe Kucinski
How Much Horsepower Every Corvette Engine "LOST" in 1972
Joe Kucinski
Top 10 DOs and DON'Ts for Protecting Your Convertible Top!
Michael S. Palmer
Top 10 Most Explosive Corvettes Ever Made: Power-to-Weight Ratio Ranked!
Joe Kucinski
150 hp to 1,250 hp: Every Corvette Generation Compared by the Specs That Matter
Joe Kucinski
8 Coolest Corvette Pace Cars (and Replicas) of All Time
Verdad Gallardo
Thread Starter
Racer
Joined: Mar 2012
Posts: 476
Likes: 37
From: Lynnwood WA
Ya gotta love paid for!
The cam in the crate motor is probably a pretty good match for the TPI. Lots of bottom end but will run out of steam pretty quick. Not what most of us are looking for when we build a Corvette motor, but it will work. If you decide later that you want to wake it up a bit, add more cam, a good four barrel and manifold, and a set of headers and you'll have a nice little motor.
The cam in the crate motor is probably a pretty good match for the TPI. Lots of bottom end but will run out of steam pretty quick. Not what most of us are looking for when we build a Corvette motor, but it will work. If you decide later that you want to wake it up a bit, add more cam, a good four barrel and manifold, and a set of headers and you'll have a nice little motor.
What cam would you recommend? Keeping in mind it will have the TPI. I hate the idea of pulling apart a brand new motor. But I might get over that, with I right in front of me.
Zorro
Melting Slicks
Joined: Dec 2009
Posts: 3,233
Likes: 657
From: Thunder Bay
Personally I like the L-82 cam (GM PN 3896962). There are about a hundred aftermarket cams with similar numbers available from the aftermarket cam companies. (222 deg duration at .050" .450 lift) If you think there is any merit in the argument that modern lobe design offers an advantage, then pick your favorite company and pick a cam sith similar numbers. If you are going to stick with stock exhaust, you will probably want to pick a cam with a little more exhaust duration.
The problem for you is that your TPI isn't nearly enough to feed an engine with this cam. That TPI system was designed for the 305 and just won't let a 350 beathe beyond about 4000 rpm. A cam with the numbers I have quoted comes alive at 3000 rpm and up. That would be a bad combination. If you use the TPI, keep the cam you have. If you want more cam, you need a better induction setup.
The problem for you is that your TPI isn't nearly enough to feed an engine with this cam. That TPI system was designed for the 305 and just won't let a 350 beathe beyond about 4000 rpm. A cam with the numbers I have quoted comes alive at 3000 rpm and up. That would be a bad combination. If you use the TPI, keep the cam you have. If you want more cam, you need a better induction setup.
Race Director
Joined: May 2005
Posts: 10,674
Likes: 122
From: Millington Illinois
St. Jude Donor '08-'09
http://www.summitracing.com/parts/cr...make/chevrolet
http://www.summitracing.com/parts/cr...et?prefilter=1
Made for TPI, works with vortec lift, factory roller cam, computer compatable, Match your OD auto trans. Would love a 2200-2400 stall
http://www.summitracing.com/parts/cr...et?prefilter=1
Made for TPI, works with vortec lift, factory roller cam, computer compatable, Match your OD auto trans. Would love a 2200-2400 stall
Last edited by 63mako; Jan 7, 2013 at 12:10 AM.
Burning Brakes
Joined: Mar 2012
Posts: 871
Likes: 73
From: Memphis Tennessee
What is the weak link in the TPI setup? To even use the TPI with the Vortec heads he is going to need an aftermarket lower manifold which should flow more than stock.
Here's an article on the Scroggin-Dickey manifold, where they got over 300 horses with stock runners and throttle body and L98 cam.
http://www.gmhightechperformance.com...d/viewall.html
High flow runners and a bigger throttle body could be added later.
He can't use the L88 cam as this motor uses roller lifters. A stock LT1 cam could be got secondhand for cheap, and adds about 10 degrees of duration. I'm not sure if they have too much lift for the valvesprings though. Anything bigger is going to take expensive beehive springs.
Here's an article on the Scroggin-Dickey manifold, where they got over 300 horses with stock runners and throttle body and L98 cam.
http://www.gmhightechperformance.com...d/viewall.html
High flow runners and a bigger throttle body could be added later.
He can't use the L88 cam as this motor uses roller lifters. A stock LT1 cam could be got secondhand for cheap, and adds about 10 degrees of duration. I'm not sure if they have too much lift for the valvesprings though. Anything bigger is going to take expensive beehive springs.
Race Director
Joined: May 2005
Posts: 10,674
Likes: 122
From: Millington Illinois
St. Jude Donor '08-'09
What is the weak link in the TPI setup? To even use the TPI with the Vortec heads he is going to need an aftermarket lower manifold which should flow more than stock.
Here's an article on the Scroggin-Dickey manifold, where they got over 300 horses with stock runners and throttle body and L98 cam.
http://www.gmhightechperformance.com...d/viewall.html
High flow runners and a bigger throttle body could be added later.
He can't use the L88 cam as this motor uses roller lifters. A stock LT1 cam could be got secondhand for cheap, and adds about 10 degrees of duration. I'm not sure if they have too much lift for the valvesprings though. Anything bigger is going to take expensive beehive springs.
Here's an article on the Scroggin-Dickey manifold, where they got over 300 horses with stock runners and throttle body and L98 cam.
http://www.gmhightechperformance.com...d/viewall.html
High flow runners and a bigger throttle body could be added later.
He can't use the L88 cam as this motor uses roller lifters. A stock LT1 cam could be got secondhand for cheap, and adds about 10 degrees of duration. I'm not sure if they have too much lift for the valvesprings though. Anything bigger is going to take expensive beehive springs.
The LT4 hot cam is typical upgrade but the lift won't work without signifigant work on the heads and or springs. The cam I linked is similar in manners but limited lift for stock vortec heads. The above article is helpful. Bet the vortec aftermarket intake flows better than the factory setup. Pretty impressive numbers.