LT1 swap? - JeepForum.com
 
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post #1 of 13 Old 09-17-2019, 07:41 PM Thread Starter
Dreamscape289
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LT1 swap?

I’m new to the forum and Jeep life. Just picked up a ‘79 CJ7 that needs a complete restoration. It has a 258 I6, and no transmission. I’m considering taking it down to the frame and doing a V8 conversion. Found an LT1 out of a 90’s Buick road master with only 50k miles. So, two questions: 1) is the v8 swap worth it and 2) is a LT1 a good motor to start with or should I look for a later LS motor? And if there are threads that already exist that answer all these questions, free free to link them! Thanks all!

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post #2 of 13 Old 09-17-2019, 09:06 PM
RiverandSand
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Good site to check out is Novak conversions, they have a wealth of knowledge on V8 swaps. It's not a cheap swap, but it's well worth it. IMHO
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post #3 of 13 Old 09-17-2019, 09:55 PM
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The LT1 is a great motor in a CJ7, a lot of people have done it and a lot of parts exist. It is WAY more powerful than anything offered in a CJ by the factory but can better them all for fuel consumption if set up properly.

Whether this is the best choice for you depends on your level of skill with modern computerised engines, and how much cost you are willing to absorb. A much later LS engine, or a crate motor, would add even more power if that is what you wish and can afford, but a CJ7 is not a Ferrari with a seven slot grille.

Novak and Advance Adapters are two major companies in this field. You will need to plan out the engine and transmission package and fined which parts will fit where. You will also need fuel system changes.

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post #4 of 13 Old 09-18-2019, 04:56 AM Thread Starter
Dreamscape289
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Quote:
Originally Posted by RiverandSand View Post
Good site to check out is Novak conversions, they have a wealth of knowledge on V8 swaps. It's not a cheap swap, but it's well worth it. IMHO
Thanks. I’ll check them out.
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post #5 of 13 Old 09-18-2019, 04:59 AM Thread Starter
Dreamscape289
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Quote:
Originally Posted by BagusJeep View Post
The LT1 is a great motor in a CJ7, a lot of people have done it and a lot of parts exist. It is WAY more powerful than anything offered in a CJ by the factory but can better them all for fuel consumption if set up properly.

Whether this is the best choice for you depends on your level of skill with modern computerised engines, and how much cost you are willing to absorb. A much later LS engine, or a crate motor, would add even more power if that is what you wish and can afford, but a CJ7 is not a Ferrari with a seven slot grille.

Novak and Advance Adapters are two major companies in this field. You will need to plan out the engine and transmission package and fined which parts will fit where. You will also need fuel system changes.
I’m a decent shade tree mechanic but am no expert by any means. I’m exploring all options and may just throw a transmission in this and drive it. I’m not looking for massive power, more just some good torque and I prefer V8s in an older Jeep.
Thanks for all the advice.
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post #6 of 13 Old 09-18-2019, 05:54 AM
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LT1 has about the worst distributor placement for an offroad rig being down low on the front of the motor and you are forced to run an electric fan. I would go for a standard 350 or go ls.

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post #7 of 13 Old 09-18-2019, 06:13 AM
ZEN357
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Quote:
Originally Posted by Dreamscape289 View Post
Im new to the forum and Jeep life. Just picked up a 79 CJ7 that needs a complete restoration. It has a 258 I6, and no transmission. Im considering taking it down to the frame and doing a V8 conversion. Found an LT1 out of a 90s Buick road master with only 50k miles. So, two questions: 1) is the v8 swap worth it and 2) is a LT1 a good motor to start with or should I look for a later LS motor? And if there are threads that already exist that answer all these questions, free free to link them! Thanks all!
Stay away from the LT1/LT4 engines with the Opti-Spark system. Worst ignition system GM ever built. My Father in Law has a 95 Vette with the LT engine and optispark setup and he hates it, nothing but problems, and wished he'd bought an older model with the L98/Distributor setup.
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post #8 of 13 Old 09-18-2019, 06:18 AM
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You didn’t say intended use, so I’ll assume you’ll be using the Jeep for street driving and mild to moderate wheeling, the most common driving style basically stock Jeeps see. Not hard core rock crawling where everything is modified for the purpose.

There were three generations that used the LT1 designation. The mid nineties LT1 Gen II (last of the SBC) engines are good engine swap candidates if youre into common & cheap engines. They are rated at about 275/330, so they have more power than the 258 but not enough to worry about breaking stuff, driveline stuff. The modern Gen III LS1 5.7 engines are similar to the old SBC’s in that they don’t make a lot of low RPM torque, they make most of their power at higher RPM’s. At lower RPM’s where a Jeep operates most of the time the LS1 doesn’t make the torque to break stuff, so they are good swap options. But the Gen III stuff costs more than the SBC.

Now the Gen III 6.2 LT1 is a different animal, it makes some torque. You need to be careful or you will break stuff if not upgraded, behind one of these new Gen III corporate LT1 motors, and they cost even more than the smaller LS based stuff.

There are a lot of people out there that love these engines, both SBC & GEN III corporate stuff, and they put them in anything with four wheels, so that speaks for itself, obviously they are good engines. An added benifit of the SBC specifically is they are cheap, and parts are cheap & pleantfull.

I’m personally not into chevy engines, nor the new corporate LS based stuff. I’d rather do something a little different, but that’s just me.

It used to wheel with a guy that had a SBC 327 powered CJ-5 Willy’s. That was one fun Jeep! I can understand why people put SBC’s in Jeeps, it is almost a perfect match.

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post #9 of 13 Old 09-18-2019, 06:42 AM
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The LT1 distributors do get a bad rep but most come from the 92-93 models (which are not vented) or if they are poorly maintained. Dont get me wrong, its not my favorite setup and I have one.

The biggest thing to watch for is displacement. GM offered a 5.7 and 4.3 LT1 and they are identical externally.

The 4.3 would be a disappointing mistake on an engine swap.

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post #10 of 13 Old 09-18-2019, 07:12 AM
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Add to the engine swap the potential for breaking other parts in the drivetrain. Pretty sure a 79 would have an AMC 20 rear axle and Dana 30 front axle, neither of which is super strong. Other potential failure points are transmission and transfer case.
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post #11 of 13 Old 09-18-2019, 11:50 AM Thread Starter
Dreamscape289
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This is some excellent advice all the way around. To address some general comments:

my plan is for general use, no serious rock crawling or climbing, just some back roads and the occasional off road excursion. This is just a toy.

Not sure if I’m going to put an auto in it or a manual. I want a manual, but if I ever expect my wife to drive it, automatic it is. She has no interest in learning a manual 😢.

I don’t know what front and rear ended it has. Where are the marks to tell? Again, I’m new to all this so the advice is MUCH APPRECIATED.

I’m crafting my plan on what to do within the next two weeks and will list it afterwards for comments and feedback.
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post #12 of 13 Old 09-18-2019, 12:26 PM
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Dreamscape289,
I'll throw in my $0.02. I have a 78 CJ7 with a Tuned Port 350 Chevy (basically an L98), with a T18a four speed manual. It is a blast to drive, and has tons of low end torque, which is just what you need in a Jeep, IMHO. I also have a 95 Corvette with an LT1/6-speed manual, and the dreaded (by many) Optispark distributor. I personally don't have any issues with my Optispark, but they are susceptible to failure when water gets inside. With their placement on the front of the engine, I don't think the Jeep is the best application, especially if you do any off road or muddy trails. Getting the wiring harnesses and electronics needed for either the LT1 or the L98 can be a bit challenging. When I bought my Jeep, the wiring harness (Painless brand) came with it, but nothing was hooked up. It took me a few months working off and on to get it running, but it wasn't too difficult. Routing the wires and lengthening/shortening them took most of the time. The simplest route would probably be an old school carbureted 350. You still would need adapters/etc, for which Novak is an excellent source. Keep us posted on what you decide.

Regards,
John
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post #13 of 13 Old 09-18-2019, 12:31 PM
RiverandSand
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Since you have a 7, your choices are a bit better for trans choices. The manuals could be any of the popular 4 spds or a nv3550 which is a 5 spd or autos could be a 700r4, 4L60e or 4L80e. If you plan on keeping it 4x4 all of those choices have adapters to adapt it to the Dana 20 which is the transfer case in a 79. I wouldn't worry to much about the AMC 20 rear end, if set correctly it will handle a SBC. These were a corporate rearend used in many models including AMXs and Javelins which had up to 401ci motors in them.
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