Grand National motor swap input.....

[NotRightInTheHead]

Good afternoon. My quest for information has led me to the Jeep-CJ site. I am sure this will be the first of many....MANY questions surrounding this subject, but I have to start somewhere.

I have recently purchased an 84' Grand National motor (complete with all the associated goodies) that a gentleman pulled from his car to build a bracket car. It's all there as far as an operational motor goes.

My intention is to bolt this motor in along with a ford T-18 Transmission and the t20 xcase out of my cj. Novak makes pretty much all the adapters to make this a 'bolt in' process.....so, now the questions.

1) I read while doing research (hours....and hours......and hours...) that when going from an automatic to manual on the 3.8 the flywheel has to be changed. Anybody have experience with doing this type of swap?

2) Has anybody adapted the 3.8 to a T-18 and the t20? Anybody know of any issues with this setup?

I appreciate any and all imput on this. Thanks for your time in advance, Scott

 

[GARGOYLEJEEPER]

1. Automatics have flex plates.
2. Issues will be exhaust, drivers side mainly, all other dimensions will fit.

You will need a complete manual clutch pack. Bell Housing, Flywheel, Disc, Pressure Plate, Throw Out Bearing, Fork, Pilot Bushing & Clutch Linkage.

 

[tarry99]

Good afternoon. My quest for information has led me to the Jeep-CJ site. I am sure this will be the first of many....MANY questions surrounding this subject, but I have to start somewhere.

I have recently purchased an 84' Grand National motor (complete with all the associated goodies) that a gentleman pulled from his car to build a bracket car. It's all there as far as an operational motor goes.

My intention is to bolt this motor in along with a ford T-18 Transmission and the t20 xcase out of my cj. Novak makes pretty much all the adapters to make this a 'bolt in' process.....so, now the questions.

1) I read while doing research (hours....and hours......and hours...) that when going from an automatic to manual on the 3.8 the flywheel has to be changed. Anybody have experience with doing this type of swap?

2) Has anybody adapted the 3.8 to a T-18 and the t20? Anybody know of any issues with this setup?

I appreciate any and all imput on this. Thanks for your time in advance, Scott

The swap is no different than the early 225......all the bolt patterns , block, crank are the same.........an after market 30-35 lb flywheel can be purchased from TA Performance in Arizona........which may require balancing with your rotating assembly. Its good that you have a later Jeep as you will need the extra room up front to fit this in.

You say a 1984 GN motor? Turbo-charged I assume? The 84 motor was in 1984 way ahead of it's time with sequential timing & fuel injection but it did also come with a host of other problems.........called the "HOT AIR" motor as this was before inter cooling was available which Buick did not inter cool until late 1986.

That turbo I believe is Top mounted so you may have some issues in fitting that under a standard hood on your Jeep. Also heat coming off that to the firewall has always been an issue..........The other problem with those early motors is being able to find an after market ECM that will talk with the early timing and fuel systems........as I don't think the originals can be re-flashed. If you can get all the systems that currently control the motor now that would be great!
I have seen them done before but not sure what systems were used.........

The early HOT AIR motors were also known for detonation and were hard on Crankshafts , Rods & bearings. The early Turbo Cranks are next to impossible to find that are not already way undersized.........the only option is an aftermarket steel crank if you can find one and they are about $1200 per copy.

Hopefully you have some experience in doing a swap such as this........they are a pretty neat package but do require lots of attention to get them right.

 

[Dan77CJ7]

what are you going to do about turbo lag? will that effect wheeling @1000rpm, do they spool at low rpms? I would wonder about the torque @1000rpms where you'll be doing most of you're wheeling.

 

[Futurmultimulti]

Evening everyone. It is not letting me sign in under my name, so I had to create another to be able to post.

As for the flywheel, I know from reading that there is a chance if I find someone knowledgeable I can get them to balance it similar to the flex plate, but it sounded like a 50/50 chance I would have to bring everything along and have it balanced. I'm hoping for the best but do expect the worst. I am using a ford T-18 Transmission which is a pretty standard bolt on (so much so Novak makes adapter kits and describes this adaptation as 'pretty straight forward') because it has the creeper gear in it as opposed to the 3 speed that came in the jeep and its a damn heavy duty Transmission .

The motor I purchased has everything....all the pipes, the ecm, all the brackets...wiring...etc etc. Right away I know that cooling will be an issue but I also have read that certain model G body cars (v-8's) have radiators that will handle this with an electric fan setup. This motor has 48k on it and was pulled only to build a bracket car. I know the only thing done to the motor was a chip. I have read where they use the later heads on these motors and bolt up an intercooler and change the ecm to a later one and such. My intentions (at this point anyways) are......

1) Get it bolted in and bolted up to this Transmission /xfer case.
2) Get it operational in its present state and motivating the jeep.
3) work the bugs out of the manual tranny/ turbo boost situations and then..
4) Build it to the point of thinking I might need to wear depends while driving.

I've joined the GN page for the technical articles on this motor and there is a multitude of opinions on changing the hot air to intercooled and such...but there are also many...many articles on upgrades to make this thing go while retaining it's non-intercooled status. I understand bolting an old Dauntless Buick 225 V6 in and going is just a bit easier than bolting THIS Dauntless Buick 225 V6 in....but I think....if from the learning standpoint if nothing else...this will be project that will be quite the interesting ride...eventually.

Now hopefully I can sign back in under my original screen name. It's locked me out, doesn't recognize my password or screen name and the function to notify someone has been disabled.

 

[Dan77CJ7]

Evening everyone. It is not letting me sign in under my name, so I had to create another to be able to post.

As for the flywheel, I know from reading that there is a chance if I find someone knowledgeable I can get them to balance it similar to the flex plate, but it sounded like a 50/50 chance I would have to bring everything along and have it balanced. I'm hoping for the best but do expect the worst. I am using a ford T-18 Transmission which is a pretty standard bolt on (so much so Novak makes adapter kits and describes this adaptation as 'pretty straight forward') because it has the creeper gear in it as opposed to the 3 speed that came in the jeep and its a damn heavy duty Transmission .

The motor I purchased has everything....all the pipes, the ecm, all the brackets...wiring...etc etc. Right away I know that cooling will be an issue but I also have read that certain model G body cars (v-8's) have radiators that will handle this with an electric fan setup. This motor has 48k on it and was pulled only to build a bracket car. I know the only thing done to the motor was a chip. I have read where they use the later heads on these motors and bolt up an intercooler and change the ecm to a later one and such. My intentions (at this point anyways) are......

1) Get it bolted in and bolted up to this Transmission /xfer case.
2) Get it operational in its present state and motivating the jeep.
3) work the bugs out of the manual tranny/ turbo boost situations and then..
4) Build it to the point of thinking I might need to wear depends while driving.

I've joined the GN page for the technical articles on this motor and there is a multitude of opinions on changing the hot air to intercooled and such...but there are also many...many articles on upgrades to make this thing go while retaining it's non-intercooled status. I understand bolting an old Dauntless Buick 225 V6 in and going is just a bit easier than bolting THIS Dauntless Buick 225 V6 in....but I think....if from the learning standpoint if nothing else...this will be project that will be quite the interesting ride...eventually.

Now hopefully I can sign back in under my original screen name. It's locked me out, doesn't recognize my password or screen name and the function to notify someone has been disabled.

Right on, I hope this swap turn out great pics are always nice:drool: Good luck sound like a fun build. "The parts hunt" is always thrilling...

 

[tarry99]

Evening everyone. It is not letting me sign in under my name, so I had to create another to be able to post.

As for the flywheel, I know from reading that there is a chance if I find someone knowledgeable I can get them to balance it similar to the flex plate, but it sounded like a 50/50 chance I would have to bring everything along and have it balanced.

There is normally nothing to balance on a flex plate.........the balance or lack there of comes from the attached Torq converter that is balanced partially by weight added and the fluid inside.

You should balance your rotating assembly to your flywheel if your planning on spinning it much.