Drivetrain planning

[Petescj]

Im in the planning stages for the drivetrain of my 83 CJ7 project. The Jeep comes with the AMC 258 i6 / 4.2l / T-5 / Dana 300 . The T-5 is the first piece Im going to ditch.

Jeep Drivetrain Options:

1. AMC 258 i6 / 4.2l / T-18 or SM 465 / Dana 300

2. 360 / T-18 or SM 465 / Dana 300

Now the two above examples are pretty standard and dont require alot of thought as far as putting either combo in. Problem is Ive been thinking.

I dont want to do a Chevy conversion cause its quite popular and I wanted something different if Id stray from the AMC engines.

The combination that has been floating around in my tiny little brain these days?

Pontiac 455 / SM 465 / Dana 300 .

The Pontiacs make plenty of good torque wich is what Im looking for. I know it wont be as "cheap" as a Chevy and parts wont be as readily available. Thats not my purpose. It would be different and a viable combo.

Im very open to discussion on this. Ive only seen Limited info on the torque curves and with the correct cam I think it'll make a great combo.

I like a good crawl ratio so I'll go 4 to 1 in the Dana 300 with 3.73 gears. That way I still have street driveability with 33 inch tires.

 

[CJ]

70 Buick 455

350 hp - 510 lb-ft!

-->> Buick V8 engine - Wikipedia, the free encyclopedia
-->> 400, 430, 455 Engine Specs - Team Buick Forum

History and specs...
-->> History of the Buick 455 Motor

 

[Petescj]

Yeah I was looking at Buick and Olds as well. I'll have to check the links when I get a chance tomorrow. I believe the Pontiac came in at 550 lb-ft but not sure what year. That was at like 2850 rpms. Id like to see some torque curve charts to see how it increases from idle on up.

70 Buick 455

350 hp - 510 lb-ft!

-->> Buick V8 engine - Wikipedia, the free encyclopedia
-->> 400, 430, 455 Engine Specs - Team Buick Forum

History and specs...
-->> History of the Buick 455 Motor

 

[Old Dog]

IMHO a big block is to heavy for good off road performance. (rock crawing anyway)
I find myself thinking V6 instead of my V8.

 

[mtnwhlr]

IMHO a big block is to heavy for good off road performance. (rock crawing anyway)
I find myself thinking V6 instead of my V8.

Thats the first thing I thought of is how much does one of those weighs

 

[csuengr]

Here is a link to engine weights.

Popular American V8 Engine Dimensions

A 455 is much more than you will ever need. I used to have an Early Bronco with a 302, NP435, Dana 20 and the little engine had more than enough grunt for slow going, plus pull it at 60mph up to the Johnson tunnel. Never needed to go above 1500 rpm on the trail.

T-18 or SM465 with a 4:1 Dana 300 is around 100:1 crawl ratio, which is almost stupid slow. Seriously stupid slow with a 455. You will run out of traction long before you run out of torque.

 

[CJ]

Big blocks are heavy!

That being said, the Pontiac 455 never even came close to the Buick 455 torque specs (even the super duty).

-- Specs on the 455 Pontiac Engine | eHow.com
-- Pontiac V8 engine - Wikipedia, the free encyclopedia

 

[Petescj]

Big blocks are heavy!

That being said, the Pontiac 455 never even came close to the Buick 455 torque specs (even the super duty).

-- Specs on the 455 Pontiac Engine | eHow.com
-- Pontiac V8 engine - Wikipedia, the free encyclopedia

Now now 500 ft / lbs is rather close to 510 ft / lbs no? Didnt read the weight yet though. That could be a big ( literally ) factor.


The 455, with its "undersquare" dimensions (long stroke relative to bore), emphasized torque over hp, and though advertised as less powerful than some high-performance iterations of the 400, it had a torque rating of 500 ft/lbs.,

 

[BusaDave9]

T-18 or SM465 with a 4:1 Dana 300 is around 100:1 crawl ratio, which is almost stupid slow. Seriously stupid slow with a 455. You will run out of traction long before you run out of torque.

Yes that is very low. If you do much rock crawling you can use that low gearing. I have 97:1 crawl ratio and there are many times I wish it was lower. (I also have 36 inch tires).
I shift into my lowest gears for the roughest rocks.

I'm not looking for high torque. I'm not giving it much gas. What I'm looking for is low speed. When I come across a rock almost as big as my tire I want to first press my tire against the rock then inch my way up it. I also want to inch my way down the other side.
Low speed not high torque, that's the advantage of extra low gearing.

 

[Petescj]

70 Buick 455

350 hp - 510 lb-ft!

-->> Buick V8 engine - Wikipedia, the free encyclopedia
-->> 400, 430, 455 Engine Specs - Team Buick Forum

History and specs...
-->> History of the Buick 455 Motor

I got to look at a little more info today. I think your on to something with the Buick over the Pontiac. Not that the Pontiac is a slouch or anything but there are a couple advantages that make it a little easier than the Pontiac.

My thoughts on the Pontiac were based off 2 cars I owned. A 68 Pontiac Tempest with a swapped in 455 and a 75 Grand Prix with the 400. Either one of those heavy cars could fry a set of tires quite easily. Alot of fun when I was younger.

Here is a link to engine weights.

Popular American V8 Engine Dimensions

A 455 is much more than you will ever need. I used to have an Early Bronco with a 302, NP435, Dana 20 and the little engine had more than enough grunt for slow going, plus pull it at 60mph up to the Johnson tunnel. Never needed to go above 1500 rpm on the trail.

T-18 or SM465 with a 4:1 Dana 300 is around 100:1 crawl ratio, which is almost stupid slow. Seriously stupid slow with a 455. You will run out of traction long before you run out of torque.

Thanks for the link on the wieghts. That was just the kind of useful info I needed. I never heard anyone complain about the 401 being to heavy for there Cj at 600 lbs. The 455 Buick is 40 more lbs. Bet I can dump 1/2 that by going with an aluminum intake.

Yes that is very low. If you do much rock crawling you can use that low gearing. I have 97:1 crawl ratio and there are many times I wish it was lower. (I also have 36 inch tires).
I shift into my lowest gears for the roughest rocks.

I'm not looking for high torque. I'm not giving it much gas. What I'm looking for is low speed. When I come across a rock almost as big as my tire I want to first press my tire against the rock then inch my way up it. I also want to inch my way down the other side.
Low speed not high torque, that's the advantage of extra low gearing.

Yup thanks Dave , Im looking for that stupid low. I guess I should have explained a little more about what I want out of the Cj. When Paragon Adventure Park was here in Pa. there was some pretty nice rock trails. Since Paragons closure Rausch Creek is the closest place to me. Raucsh has a more varied terrain.

I plan on traveling around more within the next few years since the kids are older now. Id like to have that low end grunt to help me with hills and in and out of mud holes at times. My Cj is going to be heavy all the way around. I'll have a good deal of armor , swing away tire carrier , heavy boatsides , winch and bumper as well as full coner armor.

I look forward to more replies.

 

[Petescj]

IMHO a big block is to heavy for good off road performance. (rock crawing anyway)
I find myself thinking V6 instead of my V8.

In all our years together I think this is the first time we disagree. Not really though. As far as crawling it may be a little heavier than your 575 lb. 350 Chevy. I'll deal with that to be cooler than you.

Thats the first thing I thought of is how much does one of those weighs

I was just reliving my youth and said "Hey that would be cool". Wieght wasnt on my mind but now Im not sure its going to be a real factor.

 

[mtnwhlr]

In all our years together I think this is the first time we disagree. Not really though. As far as crawling it may be a little heavier than your 575 lb. 350 Chevy. I'll deal with that to be cooler than you.



I was just reliving my youth and said "Hey that would be cool". Wieght wasnt on my mind but now Im not sure its going to be a real factor.

Are you building a hotrod or a 4wheeler? I just don't see the need for a bigblock in a 4Wd unless you are mud racing or something else like that. I agree with what BusaDave said. But then we live Colorado where the 4wheeling is different then what you see.

 

[Old Dog]

I'm really thought that 455 would weigh alot more than it does.
Must be thoes 8 hugh holes it has to lighten it up.

 

[BusaDave9]

I'm really thought that 455 would weigh alot more than it does.
Must be those 8 hugh holes it has to lighten it up.

 

[tarry99]

Im in the planning stages for the drivetrain of my 83 CJ7 project. The Jeep comes with the AMC 258 i6 / 4.2l / T-5 / Dana 300 . The T-5 is the first piece Im going to ditch.

Jeep Drivetrain Options:

1. AMC 258 i6 / 4.2l / T-18 or SM 465 / Dana 300

2. 360 / T-18 or SM 465 / Dana 300

Now the two above examples are pretty standard and dont require alot of thought as far as putting either combo in. Problem is Ive been thinking.

I dont want to do a Chevy conversion cause its quite popular and I wanted something different if Id stray from the AMC engines.

The combination that has been floating around in my tiny little brain these days?

Pontiac 455 / SM 465 / Dana 300 .

The Pontiacs make plenty of good torque wich is what Im looking for. I know it wont be as "cheap" as a Chevy and parts wont be as readily available. Thats not my purpose. It would be different and a viable combo.

Im very open to discussion on this. Ive only seen Limited info on the torque curves and with the correct cam I think it'll make a great combo.

I like a good crawl ratio so I'll go 4 to 1 in the Dana 300 with 3.73 gears. That way I still have street driveability with 33 inch tires.

Pete,

Pontiac 455 w/ 510 ft lbs of torque? WHY????? Your thinking all the right things w/ the 465 @ 6.55x4.0x3.73=97.726 crawl ratio...........With all that Mechanical Advantage all you need is an average motor with 200+ HP & 300 ft lbs of torque...............keep in mind your big 455 @ 510 ft lbs is doing that at 2800 rpm's..........when are you going to climb a hill or rock at 2800 rpms?

I would do either a small block V8 of your choice or V-6 and Fuel Inject it...............clean running a bunch of low end coupled with that crawl ratio...........at your numbers and 33 in tires @ 1000 rpm's =1.00499 mph and @ 800 rpms or near Idle .80399 mph.......personally anything over 70 CR is more than healthy.

Want to take a ride on the wild side.........I just picked up two of these 3.8 Dauntless Buick 225 V6 turbo motors.

 

[IOPort51]

I think you are re inventing the wheel and fixing something that isn't broke.

The AMC l6 is bullet proof dependable and the rest of the drive train is engineered for it. and there are about a dozen things you can easily do to find a few extra ponies if you really feel they are needed.

the object to this game is to make it back to the house under your own power and the l6 is your best bet IMHO. and to top that off it is more than likely the most cost effective option for your build.

 

[csuengr]

Rick Pewe (don't know how to do accents) used to have a flatty with a 455 in it. It was a pretty nifty jeep. Not my cup O'tea, but I'm just me.

 

[Petescj]

Alright I guess I'll re think this.

 

[jasonmark1993]

I think you are re inventing the wheel and fixing something that isn't broke.

The AMC l6 is bullet proof dependable and the rest of the drive train is engineered for it. and there are about a dozen things you can easily do to find a few extra ponies if you really feel they are needed.

the object to this game is to make it back to the house under your own power and the l6 is your best bet IMHO. and to top that off it is more than likely the most cost effective option for your build.

I agree. If you want to do normal Jeep wheeling (crawling and trails), the best bet would be what you have or a fuel injected V6 or small V8. Hell a little diesel would be great. An auto with a low stall helps alot too.

Unless you want to diminish the wheeling ease I'd steer clear of the big power V8. Mine is a bear to wheel in now, but I wasn't building a trail machine either.

 

[Petescj]

Ok thanks. Nice to hear from someone with experience. Im going to start looking into building up a 360.

I agree. If you want to do normal Jeep wheeling (crawling and trails), the best bet would be what you have or a fuel injected V6 or small V8. Hell a little diesel would be great. An auto with a low stall helps alot too.

Unless you want to diminish the wheeling ease I'd steer clear of the big power V8. Mine is a bear to wheel in now, but I wasn't building a trail machine either.