The Stovebolt Site Forums The Shop Area The HiPo Shop LS1 conversion or not??

I have a 51 3/4 ton with a 283 and the original muncy 4 speed on the floor. It is a great daily driver(which I do) but the rear end geared too high. I plan on changing the rear gear and also the engine and tranny. I would like to upgrade to a the LS1 and t56 because of efficiency and the power I don't plan keeping the motor or tranny I currently have.

I have never tackled this before and have found a great tech website web page to help with this.

Has anyone done a conversion like this?? I would like some advice on this.

You mean that the stock rear end is geared too low? That is the usual complaint around these parts.

283 is a sweet engine.. will run forever!!

I have fond memories of the 283s I've run in the past. But I'm not sure I'd run one in a daily driver today. I like a little more umph.

You're starting with a 3/4-ton truck with 8-lug hubs and talking about swapping in a motor known for its top end horse power. The LT1 makes more power than the TPI motors that proceded them, but don't work as well at slower speeds.

I'd like to read a couple paragraphs explaining how you want to use the truck when its finished. For me at least its easier to advise how to build a truck in the context of its intended use.

For instance if you plan to use this truck as a truck the LT1/T56 is likely the wrong choice. On the other hand if you are building a hot rod that will never carry more than a gallon of milk for that little girl in the gallary pictures, then the LT1 could be perfect.

Wait a minute here.. A stock LS1 hands down creates more torque than any other small block chevy out there. They create as much torque as most stock bigblocks do.

With the right cam choice an LS1 will have a ton of bottom end torque. There are more than a few 450rwtq LS1's roaming around.

Now if you are towing with it, don't use the M6.. The 5/6th gears don't have a lot of meat to them and will tear apart with any decent load.

I'm swapping a LS1 and 4L80E in to my 63 right now. I'd be glad to give you as much info as I can. Also check out LS1tech.com. Here is a link to my truck on bolt, but if your on a dial up it may take a little bit http://www.stovebolt.com/bboard/cgi-bin//ultimatebb.cgi?ubb=get_topic;f=5;t=001127

bb51,
Will be right there along with you putting the LS1 into my 49 Chevy. I haven't decided on a tranny yet, but I'm looking for a manual five speed out of a later model truck (they are just hard to find for the right price).

With the later model manual trannies there is also the possible issue of the rear tranny housing where the shifter is mounted being too far to the rear. I've heard of a few shops using the heavier gearing in a S-10 standard tranny to shorten the tranny length for older cars and pickups.

Let us know what you decide and be sure and post pics. If I get around to it over the Christmas break I'll take some before pictures of what I plan to do.

--Matt

Regarding fears that the LT1 has too much top end and not enough torque, and is only suitable for a "gallon of milk", you have to look at the original stovebolt engines in these trucks. I had a 235 in my 52 3/4 ton that probably only had around 200 lb-ft and barely over 100 hp, and I've loaded that truck with amazing amounts of cargo and even towed with it for 400 mile distances.
Compared with the straight six engines, the LT1 is a powerhouse and would be more than adequate.

Regarding the LS1 engine, I would personally try to get ahold of a 6 speed manual F-body transmission with that double overdrive. With the extremely tall overdrive options, you could keep your short rear end gears in the truck and not have to worry about it.

Go to Speedway Motors to get a traditional V8 engine mount kit adapter for the LS1 engine. Then adapting your 283 to an LS1 is a no-brainer.

And yes, the LS1 has big-block like torque, but there are still big blocks with far greater torque. The BOP 455, for example, have nearly 600 lb-ft of torque with mild mods that will still run on pump gas. The 454 and 427 have over 500 lb-ft of torque on pump gas (more when built up). The LS1 does compare with some big blocks, but doesn't have more torque than all big blocks.
It is, however, a great choice that will give you big-block like power with the economy of many 4-bangers.
Good choice.

Question...how is your steering box set up for the V8?

Easy guys, I was only using a little hyperbole to suggest that the question would be much easier to offer a meaningful answer to with a little context.

Also, I misread the original post and was thinking of the LT1, not the LS1. But that's old age and beer...

Still I think its important to start with a clear concept of how you are going to use the truck before you ask someone to comment on what motor you are going to run.

My own fleet of trucks include a stock 235, a GMC 270, an old small block and an injected 454. Each one is used differently and the different motors make a difference. If a 3/4-ton pickup is going to be used to haul heavy loads and pull a trailer you would certainly want a different motor than if you primary use is running down a drag strip or parking it at shows.

Oldsub..

The LS1/4L80E conversion going in to my truck is to tow my race car to the track. That is it's main purpose. However, I did build a forged bottom and and have decided to whack it with a healthy 2 stage N20 setup.

The truck should have about 380rwhp/rwtq NA and get 22mpg. Again, it's all about set up.

I am overwhelmed by the information given to me. I am really looking forward to the build. I have been told that the t56 6 speed would be a good choice for the combo.

My 51 is a 3600 and a six lug, so it isn't such a big truck. I am using it for all kinds of stuff right now, like hauling dirt, x-mas trees bicycles, toys, wood, and rescue swimmer gear for work, whatever.

The bottom line is driving a 283 is great for now but I need something with more power. My goal is to keep the exterior stock, and the drivetrain up to date. To get there - engine/tranny wise is the question.

I would advise not using 5th and 6th while towing or pulling if you go with a M6.. For the things you mentioned above, I don't see a major issue. (6 1/2' bed I am assuming). They are great trany's don't get me wrong, but those 2 gears won't last a long time if pushed. There just isn't a ton of material on them.

You still have the solid axle in the front of your truck?
Are you thinking bone stock LS1?

It appears you have already checked out the hybrid section on LS1tech, but the 01-02 f-body (also known as the truck manifolds) would give you the most clearence and are the second best flowing stock manifold. If you can fit the C5 Z06 manifolds go with those unless you are planing on using and aftermarket long tube header.

With my 63, I put the motor back as far as I though possible with out cutting the firewall. There is no way a M6 would fit right unless bucket seats were installed as the shifter would be basically under the seat. There is a ton of room in my truck to move the motor forward if I wanted (probably 12" or so). An M6 would then work.

If you want, I need to pull the dummy motor back out and put my M6 on it to put back in to the Camaro, I'd be happy to slide it in the truck with the M6 real quick, take some pics to show you where it would sit currently.

bb51..I went with a stock crate 350 with a turbo 400 (w/shift
kit) & it has more than enough torque & hp to get you around town & moves very strong on the freeways (70+mph) ! I had
a friend install a 250 F--d Dana 61 with posi in the rear (3:55's)
This seems to be a good combo for my mountain & freeway driving ! MPG's are around 14 to 18...The only mods on the
engine were: MDS dist., Eldebrock manifold with a 650 carb !
I have since disconected the secondaries to help out my "lead
foot" or should I say supress my lead foot ! My GMC is a '53 3/4 ton w/8 lugs, that is why I went with the F--d dane 61 !

Am I confused?

I thought sure a 3600 was a 3/4-ton and I thought all AD 3/4-tons had 8-lug hubs. How long is the bed? What configuration is the driveline? Open or torque-tube?

Could you may have a 3/4-ton with 1/2-ton axles?

My primary tow vehicle, used for dragging home old trucks, is a 454 with a T400. I figure if (when) the trans ever gives up I'll replace it with a 4L80.

That truck is really a little new to talk about here, but has 170,000+ miles on it so I expect things to start breaking. But it only gets driven a few thousand miles most years so it may last a long time, and even if I could double my fuel mileage from 10 to 20 mpg at 3000 miles a year and $2.50/gallon it would take at least three years to pay for the new transmission, so I'm not in a hurry.

The truck is a 1-ton four-wheel-drive and I've used it to haul home things like my '51 2-ton COE. Most guys dealing with those loads would probably choose Diesel power. But I like the big block.

You probably don't need as much power to move your race car around and will likely get along fine with your LS1. I like to know how something is going to be used and what the owner likes before responding with advice. And that's the point I'm trying to make here. Tell people how you're going to use something before asking them if your plan is going to work.

Oldsub,

Is it a stock big block? If so I take bets my little LS1 would produce more torque Care to bet a 6-pack of good beer?

Old sub,

When I bought the bolt, it was a six lug 3600 with an open drive line possibly from a 56 or newer. The truck ran rough when I got it but I got it running smooth (relatively speaking).

I have made my decision to put in the LS1 with the t56. I think it a sound decision with fuel economy and power at the same time.

I still have straight axles up front and am deciding on whether or not to M II or the Camaro rolling chassis. Either way, I am going from a six to 5 lug for compatibility.

I know a lot of bolters would scoff at the idea of changing the drivetrain and suspension. Don't get me wrong, I love an absolute stock Chevy but for me and my daily driving, I need the reliability. I probably will not lower the stance of the truck either if I can help it.

You're on if you're willing to try it tractor pull style in my yard.

Chain stretched tight trailer hitch to hitch, and I do mean tension on the chain, then prove your torque when the gun fires by pulling the other truck.

Actually I'll provide the beer if you'll show up at my place with your truck, and while I know what I'm going to do when mine breaks, I'm in no hurry to spend that money on what today is just a work truck.

I have visions of a 572 and a 4L80 but it can wait...

I don't have the right resources handy to verify it, but I'm pretty sure a 3600 came stock with 8-lug wheels. If you can find a copy of the 1951 Restoration Pack it will confirm (or deny) that. Look in the Tech Tips to learn how to get one if you can't find one online somewhere.

I have one at home, but I'm about as far (Orlando) from home (Seattle) as I can get and still be in the continental US, so that doesn't do any good right now.

Provided I'm right, the significance may be only that its already got a modified drivetrain, so your modifications are not 'ruining' a stock truck, only making it closer to what you want it to be...

I want to say my 49 6 1/2" bed was 8 lug.


I like the whole tractor pull idea, but with todays technology (dyno's) there is no need to pull two trucks apart using the old school method besides, your shear mass of the 1 ton, iron BB and 4wd drivetrain would give you the upper hand. I bet you have almost 1500lbs on my truck.

But, if there is a dyno by you, I'll pay for your dyno and your beer if you win Other wise your stuck paying your dyno and buying me beer..


BTW, about one year ago, I put a head cam LS1 together for a friend. It was only 346ci but it smacked around the carbed alum head 427 that rolled off the dyno just before. Made something like 10ftlbs more and over 30rwhp more. The 427 barely broke the 400rwhp / 400rwtq mark where the LS1 made 437rwhp / 413rwtq. Both cars were manuals and dynoed in a 1-1 gear..

I wasn't born yesterday . Add the chains, binders and tools and I'm sure its more like 2000 lbs at least.

I'm sure there is a dyno somewhere around Seattle, but I don't actually know where. Besides, I'm in Florida for a while anyway and the truck is in Washington.

Just having more torque isn't the whole answer for towing; where the torque comes in makes more difference. The stock big block probably has more torque at 2,500 RPM and less.

The stock big block has torque as flat as a table top from at least idle to 4500 rpm, and a LOT of it.

With the right setup I have seen 346ci LS1's pull 350rwtq by 2,500rpm, 400 by 3,500, 450 at 4,500 with 400 still at 6,500 rpm.. Yes I understand that might be a little peaky compared to a BB's off idle tq but my point is they make plenty of tq to pull with.

Here is a graph from my now sold 2001 SS. Had I known then what I know about cam timing and valve events, it would of had a much different cam in it. This is with stock heads http://73-ls1.com/misc/Torque_open_vrs_closed.bmp
Differene between the 2 in torque is open headers vs closed. Who would think open headers reduces TQ??

I don't know the torque curve of my bb but I do know that with the 4.11 gears in the differentials it is spinning pretty fast a 70-75.

I've wondered where it would be on the torque curve at a freeway cruise if I managed to install a 4L80.

I still believe the old saying that there is no substitute for cubic inches. If a 350 can make 500+ foot pounds of torque I would expect another 100 cubes to be worth 650+ and 222 more cubes (in a 572) is going to be able to go over 800 using a similar setup.

I like my big blocks.

The reason to use a big block for towing is cooling, not raw torque. A small block pushed as hard as the LS1 has difficulty getting all the heat out of it. Sure, it will pull hard full throttle in a drag race, but it takes a big block to be able to pull full throttle for more than a minute or two without overheating.

There's a reason big blocks are used for things like swamp fan boat motors- they still run cool when pushed hard.

Alloys also have a lot to do with cooling and keeping things cool. Hot lapped at the dragstrip my ols SS would stay right in the 185-190 range. My buddies auto-x vette also stays nice and cool. Sorry, I don't buy the heat exchange theorey.

With the right radiator / fan set up you can keep that motor real cool.

I don't know that I can buy that.

I'm going to keep my big block, but when its working it does get real hot.

Any engine would.

On my '68 Corvette, I overbuilt the cooling system because of how hot the small block always got. I had read that Corvettes with their tight engine bays tended to overheat with 427's in them.
I also wanted my Corvette to survive running flat out in Nevada in the summertime doing the Silver State Classic.

However, I had to dismantle my oil cooler because it was just too much. My oil would never go above 130 degrees and my water never got above 110 degrees; and it's not good for the bearings to be THAT cool because the oil doesn't flow through the journals like it should.

Now I can get the water temp up to about 160 on a hot day, and oil temp up to 180-190.

So maybe he's got a point. It's just counter to everything I've read about with big blocks in Vettes. Of course, in 1968, they didn't have gigantic 5-core radiators either.

My 465 powered '68 Firebird runs extremely cool too. Not as cool as the Vette, but about 160 to 170 degrees typically.
The 355 from the Vette now resides in an '86 tuned port IROC-Z, and it still is hot-tempered.

What temp T-stats are you running? That is a T-stats job to get it to running temp quickly. Then cycle open and closed to keep it at the temp you want it to, or close to it. Fluid can only go through a radiator if allowed (IE T-stat temp).

165 on both the Vette & Bird.