Chevy 350 swap

[mtnwhlr]

The more i think about it i'm going to go through with the swap,i've been working on the motor for awhile and its something i've always wanted to do since the day i bought it with the 700r already in it. I will get the more mounts and not look back.I will swap out the rear end for the Dana 44 . I have a set of g2 3.73 r&p's for the Dana 44 that i bought while i was in az.For some reason i thought thats what i had in m20 Costly mistake if i can't use them. I still don't know how i screwed that up. L grits just brought that to reality for me. We have no good parts store around here and i grabbed them while i was out there all the while thinking thats what i had actually carried them home in my suit case. I will never hear the end of that one from the boys at work.....i'm going to go make a drink.

So if you are going with the SBC350 go ahead and put the 3.73s in the Dana 44 and do the same with the front and I think you should be happy.

 

[HackFabrication]

Like I posted, I think you'll be okay with the 3.73's behind the SBC and 700r4. However...

Run your numbers here: Gear Ratio Calculator

3.73 gears with the 700r4 Transmission and it's 30% Overdrive at 2200 rpm, is going to have you flying at 83 mph.

4.10 gearing drops that to 75 mph.

4.56 gear drops that to 68 mph.

As a comparison, my 2002 Blazer with the 4.3L V6 and 4L60-E (Overdrive - similar gearing as the TH700R4) is turning 2200 at 74 mph (approximately). That's with 3.54 gearing and 28" tires.

IMHO, I like the 4.10's here.

 

[Lumpy Grits]

Don't expect that '20' live at all, with the SBC.
4:10 with that SBC and run'n around 2400-2500 is a good choice as that engine will run there all day without issue.
I run 4:10 in the B'bock in my 1ton crew-cab dually, and the engine loves it.
I am run'n an L80 tranny.
LG

 

[HackFabrication]

4:10 with that SBC and run'n around 2400-2500 is a good choice as that engine will run there all day without issue.

That's two votes for the 4.10's...

Don't expect that '20' live at all, with the SBC.

It's a matter of how much $$$ one wants to toss at the AMC20 . New gears, 1 piece axles, weld the tubes: And he should be okay for the wheeling/driving he does. Assuming he doesn't have a 'problem' with his right foot... Or like to play Rat Patrol and jump it over dunes...

But there comes a point where one has to balance the costs of a 9" Ford (or Dana 60) against the money spent on an AMC20 . Most of the time on a street/trail Jeep, you are just putting power to the rear axle. Don't stoplight drag the AMC20 and otherwise abuse it, it'll be fine. The Ford 9" (or Dana 60) is a great choice (for a number of reasons). But it all comes down to a balance of money spent versus utility/durability gained.

That being said.... If I had to do it all over again (and I won't - EVER), I'd have went with custom Dana 44 and Dana 60 (or a Ford 9") axles under my CJ5 . Considering the $$$$ that I spend on the 30/20 combo, it would have been the better move.

 

[Lumpy Grits]

One of the biggest issues with the '20' is the thin axle tubes.
The '20' was a result of the AMC 'beancounters'. Worst axle ever put on a CJ.
LG

 

[HackFabrication]

One of the biggest issues with the '20' is the thin axle tubes.

No arguing that. However, consider the stock weight of the CJ and the fact it came with 'dinky' tires (and a small V8, a strangled I6, or I4), it was probably adequate (according to the engineers). Besides, AMC like to use 'stuff' they had lying around. The only reason some of the 86 CJ's had Dana 44 's in the rear, was because AMC ran out of the Corporate 20 axles, and since Dana was 'down the street'....

 

[mtnwhlr]

He said he has a Dana 44 and a set of 3.73 gears to go in it this is why I said what I did. I think this setup will work fine for him. Why even debate the 20 at this point?

 

[Lumpy Grits]

He said he has a Dana 44 and a set of 3.73 gears to go in it this is why I said what I did. I think this setup will work fine for him. Why even debate the 20 at this point?

Because it's Saturday night.........

LG

 

[Lumpy Grits]

He said he has a Dana 44 and a set of 3.73 gears to go in it this is why I said what I did. I think this setup will work fine for him. Why even debate the 20 at this point?

Th OP corrected his statement(see post #13)to show he in fact has the 3:31 OEM gearing.

LG

 

[mtnwhlr]

The more i think about it i'm going to go through with the swap,i've been working on the motor for awhile and its something i've always wanted to do since the day i bought it with the 700r already in it. I will get the more mounts and not look back.I will swap out the rear end for the Dana 44 . I have a set of g2 3.73 r&p's for the Dana 44 that i bought while i was in az.For some reason i thought thats what i had in m20 Costly mistake if i can't use them. I still don't know how i screwed that up. L grits just brought that to reality for me. We have no good parts store around here and i grabbed them while i was out there all the while thinking thats what i had actually carried them home in my suit case. I will never hear the end of that one from the boys at work.....i'm going to go make a drink.

And in post #20 he said this. They way I read it is that he bought a set of 3.73 gears for the Dana 44 thinking that was what he had in the 20. That is why I posted put the 3.73s in the Dana 44 and use it and replace the gears in the front to match.

 

[bearsden]

And in post #20 he said this. They way I read it is that he bought a set of 3.73 gears for the Dana 44 thinking that was what he had in the 20. That is why I posted put the 3.73s in the Dana 44 and use it and replace the gears in the front to match.

I would like to go with the 4.10's but i do already have the 3.73 for the Dana 44 .not knowing a whole lot about gearing i'm hoping this will work for me. Thanks for all the help guys!

 

[Lumpy Grits]

Mtnwhlr-That's a very good idea.

OP--IF, you can exchange or sell that 3:73 and buy 4:10, I would do that.
Have the R&P CONFIRMED before you do/BUY anydangthing. It's a 30 year old Jeep and who knows what a PO did with it.
No matter what you do. You'll still have to buy new carriers and this is the time to look at either a LSD or true lock'n diffs.
The Dana 44 you have-What's it out of?
LG

 

[bearsden]

Mtnwhlr-That's a very good idea.

OP--IF, you can exchange or sell that 3:73 and buy 4:10, I would do that.
Have the R&P CONFIRMED before you do/BUY anydangthing. It's a 30 year old Jeep and who knows what a PO did with it.
No matter what you do. You'll still have to buy new carriers and this is the time to look at either a LSD or true lock'n diffs.
The Dana 44 you have-What's it out of?
LG

the Dana 44 came out of a86cj7.

 

[bearsden]

Mtnwhlr-That's a very good idea.

OP--IF, you can exchange or sell that 3:73 and buy 4:10, I would do that.
Have the R&P CONFIRMED before you do/BUY anydangthing. It's a 30 year old Jeep and who knows what a PO did with it.
No matter what you do. You'll still have to buy new carriers and this is the time to look at either a LSD or true lock'n diffs.
The Dana 44 you have-What's it out of?
LG

I was also told if i went with the 3.73's i wouldn't need the carriers is that correct?

 

[Lumpy Grits]

The cut off for the Dana 30 front axle is a new carrier is need'd for 3:73 and 'higher'
DANA 30 CARRIER CASE 3.73 UP 706008X (4 SERIES)

IIRC-The same goes for the D/44.
LG