do i go carbed or lt1?

i have a donor lt1 and everything needed, i also have a 700r4/4l60 and a 93 T56 transmission. im thinking of just going with a th350 transmission so i dont have to fuss with the tranny crossmember and custom driveshaft. or 700r4 for ease of installation vs the T56.

i also have a stock harness and pcm(2 of them one from a 93 and one from a 97). or should i just get a painless wiring harness?

if i go carbed, i know jack about carb motors and how to maintain/tune them. im also looking to make 320-350 rwhp out of either motor and it will be daily driven to work/school.

so what is better to go with in my 79? drop in the lt1 and go with a th350 and custom fuel setup or just go carbed?

can a carb motor make 320-350 rwhp and still be easy on gas and reliabilty? or is it the tranny that causes you to eat up the gas?

thanks for all your help and suggestions!!

 

Carbs can make just as much horsepower as fuel injection. But the low speed driveability and fuel efficiency is quite a bit better with EFI. If you are familiar with EFI, I see no reason to go with a carb.

My EFI guide can help a little in setting up your 79 to receive the engine and how to do the wiring. You can download it by going to my website and clicking on the EFI guide link. It's mostly dedicated to 1990-1992 TPI, but there are a lot more similiarities than differences with respect to the swap procedure.

 

Go with the LT1 swap. Ive been collecting parts and info on the LT1/t-56 combo for my 81Z. ULTM8Z's guide is very helpfull and his reasons are right on the money. If you need any help or info I can give you a hand as I will be doing this someday myself. I've got quite a few sites archived to help with fuel and drivetrain issues.

If yo do decide to go carb, I'm not bad with a holley as well

 

If I had all the LT1 / T-56 parts you've got, I'd be doing that swap for sure. Unless you'd rather have an auto, the T-56 is a tough tranny, and will take the abuse of ~350 HP better than a 4L60 will (although a TH350 would take it fine, but doesn't offer you OD, which then will reflect in poor fuel mileage).

With the LT1, you can make good power, but maintain respectable fuel economy due to the EFI and the better flowing heads. Using the 6-speed instead of an automatic, you can also maximize your fuel economy on the highway (remember, .50:1 6th gear! ) and you can run lower gears in the back (ie: 4.10's) and still get good mileage!

That's my $.02 .

 

okay so its getting the lt1, thats settled.

now i have to decide wether or not i want it to be auto or not. i already have a t56 in my fourth gen and i miss just cruising around in the 79, it used to have a olds 350 with a th350.

so im leaning towards the auto as i dont really want to go thru the hassle of swapping in all the T56 stuff, like pedals etc.

and im leaning towards the th350 so i dont have to make up a custom tranny crossmember and driveshaft.

any opinions as to which auto i should sway to and why? i dont think the car will see a lot of highway duty, maybe weekends.

if the t56 swap is easy enough then please let me know.

my main concern is the fuel delivery and harness. should i just go painless harness or stock harness?

thanks for all the help, i really apprecaite the fast responses.

 

If you're gonna do the auto, I'd lean towards the TH350. I think they have a better track record in terms of reliability, and then, unless you were planning on upgrading the gauges somehow, you can hook up the speedo cable like normal instead of hassling to wire up an electronic / mechanical speedo somehow. Also, parts for TH350's are cheaper (shifters, shift kits, converters). If the car isn't going to see much highway use, 3.73's would probably work nice in the back, or 3.42's, which I used to have in my '81 Z28.

 

If the car already had the pedal assy i'd say go with the T56 but if it's an auto car and you'd have to swap i'd say go with the 4L60. I think in the long run the extra work of putting it in will be well worth it with the increased mileage and drivability. My camaro is getting a LT1 and T56 right now and there is alot of help out there on www.pro-touring.com. Alot of those people post on here so they might be able to help here but if you cant get something answered try there.

William

 

thanks for all the help and links guys, its hard for me to decide the tranny choice. i know the t56 is a better route, but i dont want the extra work or hassle to swap it in. right now im just trying to figure out if its worth the hassle for a 4 speed auto or not. i was gonna sell the t56 and use the money else where.

the car had a th350 before and i didnt find it that bad at all driving around town. im pretty sure the 4l60 is a 4l60e so ill have to use the 97 pcm, im not sure if the 93 pcm can run a 4l60e. now i have to figure out which pcm ill use and what harness, can someone point me in the right direction for the painless wiriing kits?

oh and i almost forgot i do have a unused brand new accel dfi lying around that i was gonna use on my fourth gen i can use for this project if need be, i was gonna sell that as well. what do you guys think? use the dfi? im pretty sure that it doesnt have provision for the 4l60e though....this is why im leaning towards the th350...or perhaps a actuall 700r4/4l60.

 

well from what i can find on jegs.com the painless kits for a lt1 with the 4l60e is 600.00, i have to use the stock obd1 pcm. the other harness they have is without the provision for the 4l60e and that too is pricey at 365.00 and requires use of blah, blah blah, too cunfusing.

ill either try and figure out the harnesses i have or just use the dfi i have kicking around.

with the dfi ill have to use either a t56, th350, or 700r4

with the 93 harness ill have to use either a t56, th350 or 700r4

with the 97 harness ill have to use either the t56, th350, 700r4, or 4l60e.

currently in my garage are the t56 and 4l60e. so if i go th350 or 700r4 ill have to purchase them and liquidate the t56 and 4l60e.

what a dilema, can someone tell me what to use and why!!!

 

The TH350 will be easier and cheaper. If you decide that you want a t-56 at a later date, you can always swap out the TH350.

 

from the othe posts looks like the th350 will be revving to high for my liking on the highway, even though it may be once a week that it goes on the highway.

im heavily leaning towards the 4l60e now and using the 97 hanress and a 94/95 pcm.

 

ULTM8Z

any tips on swapping in a 700r4/4l60e?

 

It's almost all in kit form now. When I did mine about 10 years ago, it was a totally custom job. In fact, a company by the name of Premier Performance (they don't exist anymore) built the trans and did the swap.

Today though, I would get in touch with Bowtie Overdrives. They have everything you need to make a TH700-R4 work with your 1979 linkages and shifter. I'm running my factory shifter with the factory cable.

You'll have to relocate the transmission crossmember, shorten the driveshaft, and likely modify the transmission oil lines. However, the Chevrolet TH700-R4 will blot right up to your small block with no modifications. If you have a not-so-radical engine, I would also suggest going with a lock-up converter. I'm using a 1996 LT4 Vette torque converter. It has a lot of torque capability and it gives great gas mileage when locked up in fourth gear. Make sure you get the kit that keeps the converter unlocked until fourth gear- it makes driving a lot better.

During a recent rebuild (the other one lasted about 110,000 miles), this other shop I went to found that they could put in some heavy duty parts from a 2003 Cadillac Escalade 4L65E trans- clutches, bands, oil pump, etc. I thought that was awesome. The car has never felt this good as far as shift quality.

That's about all I can think of for now...

 

I read a really good article on the 4L65E, and they sound like a pretty good transmission.................still maybe not a TH400, but definitely much stronger than a standard 4L60E . Probably worth looking into getting some of those upgraded parts.

 

well i found the cross member:

http://www.bowtieoverdrives.com/cata...php?ITEMID=102

i have the shifter out of the fourth gen that i could use, if its possible? i wanted to use the fourthgen center console too.

has anyone relocated the park brake to the middle? like in the third and fourth gens? i have the handle and brakets for that too.

does someone make a driveshaft for this application?

i also have the stock 97 torque convertor for the 4l60e, all i was going to do was install a lt4 hot cam or a cc305, im only looking to make 325-350rwhp with it for now.