What engine to put in my 71 big block car?
10-19-2018, 12:33 PM
#1
Safety Car
Thread Starter
What engine to put in my 71 big block car?
I recently got a 71 coupe
It came from the factory with a 454 automatic
A previous owner put in a 396 block from 1969
and a 4 speed from 1973
Apparently left the original rear end as it has very high gears
So we have a mongrel here
Just put the car on the dyno and it produced a whopping 165hp at the rear wheels.
So the engine has got to go.
Now the question is what to replace it with
I want at least 350hp at the rear wheels
Crate engine?
Period correct block with mods?
LS?
Obviously I am not restoring it to stock.
and I am on a reasonable budget
Glenn in San Diego
It came from the factory with a 454 automatic
A previous owner put in a 396 block from 1969
and a 4 speed from 1973
Apparently left the original rear end as it has very high gears
So we have a mongrel here
Just put the car on the dyno and it produced a whopping 165hp at the rear wheels.
So the engine has got to go.
Now the question is what to replace it with
I want at least 350hp at the rear wheels
Crate engine?
Period correct block with mods?
LS?
Obviously I am not restoring it to stock.
and I am on a reasonable budget
Glenn in San Diego
10-19-2018, 01:09 PM
#2
Team Owner
Member Since: Jun 2000
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FWIW: you can get 350hp out of the 396.
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gleninsandiego (10-19-2018)
10-19-2018, 01:12 PM
#3
Team Owner
IMO, LS engine of your choice, I would go all aluminum, which I think is available....and build your own 200 4r auto same as I did....
I installed my 350 with L98 heads, factory '89 truck block/cam serp drive, 88-91 and later compressor.....
today, LS is the trick, but the 20 y/o install I did werks fine still......
see below for pix....
I installed my 350 with L98 heads, factory '89 truck block/cam serp drive, 88-91 and later compressor.....
today, LS is the trick, but the 20 y/o install I did werks fine still......
see below for pix....
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gleninsandiego (10-19-2018)
10-19-2018, 01:14 PM
#4
Safety Car
I bought a 1968 L71 car that was missing the original engine. It had a 1970 LT1 engine in place and it worked well. I too wanted the power of the Big Block so I went to Corvettes@Carlisle and I found a 1967 L-71 block that was a factory "Corporate Exchange" engine. These engines were made to replace the originals when they were damaged beyond repair. It really belongs in a 1967 L-71 BB car. I bought the block for $400, then I found two cast Iron "Closed Chamber" cylinder heads and off I went. Over the next year the engine was slowly built and installed in my 1968 Corvette Convertible with the 4 speed.
My car has a 3.36 rear end which seems a bit weird for a muscle car but with my 500+ horsepower it still drops into the 11's burning the tires half the way. You need to look up the rear ratio as it will be important in the selection of parts (i.e. Camshafts selection). I am making power the old fashioned way, a normally aspirated High Compression engine with headers and Water/Methanol Injection to help with compression issues. There does get to a point where it might be too much as I can't drive my car on wet roads (at all) and the engine can scare the hell out of me with it's wicked power.
I did things the old way, I re-installed a period correct 427 back into my car. I would probably not do that again if I were starting all over. GM makes some really nice crate engines with the fuel injection systems already installed and set up. I would go with a modern LS engine ( I never thought I would suggest this) and use the modern fuel injection and the result will be a nice car that is very reliable and makes horsepower. The junkyards have lots of LS engines with fuel systems and they are waiting for you!
One of the reasons I made my car "proper" by going back and putting a BB back into it was the "value" of the car. By putting a 427 back in the car and utilizing several original L88 parts my car was video taped at Corvettes@Carlisle by SPEEDVISION who were surprised that what they thought was a real L88 was not an L88. I have seen them run the video on SpeedVision multiple times, you can't miss my car, Bright Yellow with Black interior. I bought a Hood and "Wedding Cake" assembly from a documented 1968 L88 that was destroyed in 1969 in a roll-over. Fortunately the guy had removed the original hood and carburetor assembly to use something that was popular at the time. I bought the hood and had it painted to match my car, it looks like an L88 but it is not a L88. I have a radio and heat but I also have a car that stands out and breaks 0-60 in 2.8 seconds. My car has tripled in value or more with putting the BB back into it. Since it is a Factory stamped JE engine it is perfect for my Corvette since it was made in early October of 1967. I offered the completed engine to two buddies who both had original 1967 BB cars without the BB engines and they both declined until they saw and heard it run, then it was too late.
These new engines are tempting, for reliability and power. The older engines are more finicky and you have carburetors to deal with among other things. My car came with the Transistorized Ignition so I never had points to deal with but I am sure you get the idea. There are fewer people out there today that know old cars and their technology or lack of technology. My mechanics have no idea what to do with a carburetor.
If you put a modern motor in your car it will put many smiles on your face and lots of reliable power to the ground. My re-build and installation came to close to $9 k, a crate would be a lot less. You might get a deal on a DART engine, that would make over 350 hp at the rear wheels and they go on sale every once in a while. Your 396 can be made to produce way more than 350 hp but it will cost some serious money.
I hope that you find a good solution for your budget, take your time and build the engine slowly and you save more money. If you do it all at once you will spend considerably more.
Good Luck and enjoy your Corvette!
My car has a 3.36 rear end which seems a bit weird for a muscle car but with my 500+ horsepower it still drops into the 11's burning the tires half the way. You need to look up the rear ratio as it will be important in the selection of parts (i.e. Camshafts selection). I am making power the old fashioned way, a normally aspirated High Compression engine with headers and Water/Methanol Injection to help with compression issues. There does get to a point where it might be too much as I can't drive my car on wet roads (at all) and the engine can scare the hell out of me with it's wicked power.
I did things the old way, I re-installed a period correct 427 back into my car. I would probably not do that again if I were starting all over. GM makes some really nice crate engines with the fuel injection systems already installed and set up. I would go with a modern LS engine ( I never thought I would suggest this) and use the modern fuel injection and the result will be a nice car that is very reliable and makes horsepower. The junkyards have lots of LS engines with fuel systems and they are waiting for you!
One of the reasons I made my car "proper" by going back and putting a BB back into it was the "value" of the car. By putting a 427 back in the car and utilizing several original L88 parts my car was video taped at Corvettes@Carlisle by SPEEDVISION who were surprised that what they thought was a real L88 was not an L88. I have seen them run the video on SpeedVision multiple times, you can't miss my car, Bright Yellow with Black interior. I bought a Hood and "Wedding Cake" assembly from a documented 1968 L88 that was destroyed in 1969 in a roll-over. Fortunately the guy had removed the original hood and carburetor assembly to use something that was popular at the time. I bought the hood and had it painted to match my car, it looks like an L88 but it is not a L88. I have a radio and heat but I also have a car that stands out and breaks 0-60 in 2.8 seconds. My car has tripled in value or more with putting the BB back into it. Since it is a Factory stamped JE engine it is perfect for my Corvette since it was made in early October of 1967. I offered the completed engine to two buddies who both had original 1967 BB cars without the BB engines and they both declined until they saw and heard it run, then it was too late.
These new engines are tempting, for reliability and power. The older engines are more finicky and you have carburetors to deal with among other things. My car came with the Transistorized Ignition so I never had points to deal with but I am sure you get the idea. There are fewer people out there today that know old cars and their technology or lack of technology. My mechanics have no idea what to do with a carburetor.
If you put a modern motor in your car it will put many smiles on your face and lots of reliable power to the ground. My re-build and installation came to close to $9 k, a crate would be a lot less. You might get a deal on a DART engine, that would make over 350 hp at the rear wheels and they go on sale every once in a while. Your 396 can be made to produce way more than 350 hp but it will cost some serious money.
I hope that you find a good solution for your budget, take your time and build the engine slowly and you save more money. If you do it all at once you will spend considerably more.
Good Luck and enjoy your Corvette!
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gleninsandiego (10-19-2018)
10-19-2018, 02:10 PM
#5
Race Director
Member Since: Jan 2000
Location: Corsicana, Tx
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2020 C2 of the Year - Modified Winner
2020 Corvette of the Year (performance mods)
C2 of Year Winner (performance mods) 2019
2017 C2 of Year Finalist
Call Mark Jones at Vortec Pro and order a 496". 650-700+ HP depending on heads and will be dead reliable and drive anywhere.
JIM
JIM
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10-19-2018, 02:11 PM
#6
I recently got a 71 coupe
It came from the factory with a 454 automatic
A previous owner put in a 396 block from 1969
and a 4 speed from 1973
Apparently left the original rear end as it has very high gears
So we have a mongrel here
Just put the car on the dyno and it produced a whopping 165hp at the rear wheels.
So the engine has got to go.
Now the question is what to replace it with
I want at least 350hp at the rear wheels
Crate engine?
Period correct block with mods?
LS?
Obviously I am not restoring it to stock.
and I am on a reasonable budget
Glenn in San Diego
It came from the factory with a 454 automatic
A previous owner put in a 396 block from 1969
and a 4 speed from 1973
Apparently left the original rear end as it has very high gears
So we have a mongrel here
Just put the car on the dyno and it produced a whopping 165hp at the rear wheels.
So the engine has got to go.
Now the question is what to replace it with
I want at least 350hp at the rear wheels
Crate engine?
Period correct block with mods?
LS?
Obviously I am not restoring it to stock.
and I am on a reasonable budget
Glenn in San Diego
What are your goals? This makes all the difference. Is this car going to be a hotrod for hard driving and occasional drag strip runs, a daily driver, an occasional street cruiser, etc...
350 hp at the rear wheels out of a 396 is really simple. You are likely heads and cam (and possibly exhaust depending on what you are running) away from making that number. Is your current motor healthy? Doesn't burn oil, has good compression, etc...? If so, the cheapest route would be some nice aluminum heads and a flat tappet cam.
If your motor is not particularly healthy and in need of a rebuild anyway, then crate motor would be an option. This is also a simple and relatively affordable option. You could get a crate motor that would meet your power goal for around $5,000, and it would be an easy swap.
The LS is a different can of worms. Judging by your questions, you wouldn't be doing any of the engine work yourself I take it? Which means having a shop do it. Get your pocket book out. There are some distinctive advantages to the LS motors :factory fuel injection, good flowing heads, roller cams, 6 bolt mains (extra strong), better sealing surfaces, lightweight, etc... basically superior to the old SBC/BBC in every way except cost.
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gleninsandiego (10-19-2018)
10-19-2018, 07:22 PM
#7
Le Mans Master
www.vortecpro454.com
Go here, call Mark, order however much power you want. Put it in and go, proven product and fairly priced. Can't beat these engines for the money.
Go here, call Mark, order however much power you want. Put it in and go, proven product and fairly priced. Can't beat these engines for the money.
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gleninsandiego (10-20-2018)
10-19-2018, 07:48 PM
#8
put a 454 eng [2 bolt or 4 bolt]back in with a pair of oval-port aluminum heads,and a 365hp merc boat hyd cam,and a edelbrook intake and a 780 [3310 holley] carb
looks right and will make 400+hp
looks right and will make 400+hp
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gleninsandiego (10-20-2018)
10-20-2018, 08:37 AM
#9
Race Director
What does that 396 have in it for heads and pistons? And crankshaft? And what year is the block? The 65 needed a Groove machined in the rear cam journal for oiling purposes. But that 396 is paid for and can easily make 400 horsepower. Not with a marine cam though. That 365 Merc is a direct copy of the ls6 454 except for the camshaft. Low lift no duration wide load sep angle to keep the exhaust from sucking water back in. The best budget setup would be to find a 96 to 2000 l-29 engine. As long as you don't mind an electric fuel pump. That's a factory roller block. I bought them as cheap as 200 bucks. Zz502 cam can run on those dog-bone lifters. GM design that cam. GM doesn't like warranty recalls. So they make a performance cam that doesn't tear up a valve train. Yet it makes one horsepower to the cubic inch easily. And still sounds like a hot rod. The 454 / 502 ho cam is a little milder and it's still a 461 horse 502. But it has a passenger car idle.
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gleninsandiego (10-20-2018)
10-20-2018, 09:15 AM
#10
Race Director
I can't find a 396 rated lower than 325 horsepower. So maybe the first thing you should do is get this thing tuned up correctly and do a compression test.
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gleninsandiego (10-20-2018)
10-20-2018, 09:46 AM
#11
Le Mans Master
I recently got a 71 coupe
It came from the factory with a 454 automatic
A previous owner put in a 396 block from 1969
and a 4 speed from 1973
Apparently left the original rear end as it has very high gears
So we have a mongrel here
Just put the car on the dyno and it produced a whopping 165hp at the rear wheels.
So the engine has got to go.
Now the question is what to replace it with
I want at least 350hp at the rear wheels
Crate engine?
Period correct block with mods?
LS?
Obviously I am not restoring it to stock.
and I am on a reasonable budget
Glenn in San Diego
It came from the factory with a 454 automatic
A previous owner put in a 396 block from 1969
and a 4 speed from 1973
Apparently left the original rear end as it has very high gears
So we have a mongrel here
Just put the car on the dyno and it produced a whopping 165hp at the rear wheels.
So the engine has got to go.
Now the question is what to replace it with
I want at least 350hp at the rear wheels
Crate engine?
Period correct block with mods?
LS?
Obviously I am not restoring it to stock.
and I am on a reasonable budget
Glenn in San Diego
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gleninsandiego (10-20-2018)
10-20-2018, 09:47 AM
#12
Race Director
I don't think he would go back to a small block on a bet.
10-20-2018, 09:53 AM
#14
Le Mans Master
Why make an original big block car, that currently has a big block, into a small block car? 
I could see MAYBE LS swapping it but...even that is blasphemy to me....A big block car NEEDS a big block.
I wouldn't even waste time building a 396 unless its an original 396 car...(chevelle, Camaro, impala etc etc)
I could see MAYBE LS swapping it but...even that is blasphemy to me....A big block car NEEDS a big block.
I wouldn't even waste time building a 396 unless its an original 396 car...(chevelle, Camaro, impala etc etc)
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10-20-2018, 09:58 AM
#15
Le Mans Master
Why make an original big block car, that currently has a big block, into a small block car?
I could see MAYBE LS swapping it but...even that is blasphemy to me....A big block car NEEDS a big block.
I wouldn't even waste time building a 396 unless its an original 396 car...(chevelle, Camaro, impala etc etc)
I could see MAYBE LS swapping it but...even that is blasphemy to me....A big block car NEEDS a big block.
I wouldn't even waste time building a 396 unless its an original 396 car...(chevelle, Camaro, impala etc etc)
10-20-2018, 10:11 AM
#16
Le Mans Master
Big blocks are cheaper to build then small blocks... Plus he'd have to buy SB headers, accessory brackets etc etc..
A 650hp big block is around $8-9k.... A 650hp small block is around $12-13k+....
Now switching from a SB to a BB can get expensive due to needing headers, accessories, brackets etc... I did it...and it ain't cheap. LOL
Don't get me wrong, I love a killer small block.... but I wouldn't swap out a BB for one...unless maybe I was road racing or something.
A 650hp big block is around $8-9k.... A 650hp small block is around $12-13k+....
Now switching from a SB to a BB can get expensive due to needing headers, accessories, brackets etc... I did it...and it ain't cheap. LOL
Don't get me wrong, I love a killer small block.... but I wouldn't swap out a BB for one...unless maybe I was road racing or something.
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gleninsandiego (10-21-2018)
10-20-2018, 10:28 AM
#17
Le Mans Master
Big blocks are cheaper to build then small blocks... Plus he'd have to buy SB headers, accessory brackets etc etc..
A 650hp big block is around $8-9k.... A 650hp small block is around $12-13k+....
Now switching from a SB to a BB can get expensive due to needing headers, accessories, brackets etc... I did it...and it ain't cheap. LOL
Don't get me wrong, I love a killer small block.... but I wouldn't swap out a BB for one...unless maybe I was road racing or something.
A 650hp big block is around $8-9k.... A 650hp small block is around $12-13k+....
Now switching from a SB to a BB can get expensive due to needing headers, accessories, brackets etc... I did it...and it ain't cheap. LOL
Don't get me wrong, I love a killer small block.... but I wouldn't swap out a BB for one...unless maybe I was road racing or something.
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gleninsandiego (10-21-2018)
10-20-2018, 11:31 AM
#18
Race Director
Yeah. Bunch of stuff. Now, back to the 396. Nobody would build one. But if that's got good pistons in it it probably has a good crank in it. Even a cast-iron two bolt motor. It's going to be able to handle 500 horsepower with no trouble. Cam heads 780 Holley headers. . You're going to buy all those things if you put a 454 in it. So you put those things onto a 396. And then decide if you want to go shopping for a 454 block or not. But in the mean time, 5 degrees too retarded at full throttle is about 30 to 50 hp loss.
Last edited by derekderek; 10-20-2018 at 11:35 AM.
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gleninsandiego (10-21-2018)
10-20-2018, 12:33 PM
#19
Race Director
And a 10 buck ebay borescope will get you a look at the piston tops to get an idea of dome size or flat, which is unlikely. Head casting number will get you chamber volume and oval or square which you can tell from looking at the intake. And compression test, obviously. Post a couple pics if the Beastie.
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gleninsandiego (10-21-2018)
10-20-2018, 02:05 PM
#20
Le Mans Master
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Can you be a little more specific on your budget and performance requirements? You have us tripping over ourselves with so many options for a small block let alone a big block to but either with work here.
Do want to rebuild a good core or buy a crate motor. How much do want to race? Just cruise?
Parts store BB remans start at $2700. I don't think you can buy and rebuild a good core 454 for that.
Do want to rebuild a good core or buy a crate motor. How much do want to race? Just cruise?
Parts store BB remans start at $2700. I don't think you can buy and rebuild a good core 454 for that.
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gleninsandiego (10-21-2018)
