Lm7 swap questions and advice

[jstrong394]

I have a 84 c10 I'm redoing... Originally a 305 automatic. Motor and trans are out right now. Plans are a lm7 with Texas speed cam package and the victor jr carb intake. I'm thinking of going with a 4L80e or th400 tranny. I know I need the msd box. Curious as to what all else I will need to make the swap happen. Never did a swap before and just dunno if I'm getting in over my head mechanically and financially. This will only be a street rod

[softballnrd27]

Why carb? If it is simply for the look then jus go with a 4150 style TB. Either way make sure you get a cam spec'd for the Single Plane so you aren't leaving powe ron the table.
400 would be a little cheaper but you get O/D with the strength of a 400 in the 4l80e for not that much more. Find a good used 4l80e add a TransGo HD shift kit and converter.

[jstrong394]

The carb setup will just be easier for me to get installed... A lot less wiring.

[Wasted Income]

Putting a carb on an LS is like giving brain damage to a genius.

http://www.ebay.com/itm/LS1-LSX-LM7-...6fd50f&vxp=mtr

Add the cost of a PCM, flash, harness rework, fuel pump....save the cost of a carb, MSD box, aftermarket intake....and have new-car drivability and fuel economy from your street rod.

Plus you would then have the choice to run a 4L60e/4L80e/TH350/TH400/700R4 etc.

My $.02

[tinydb84]

Look at the what it cost thread and there are giant parts list with prices and part numbers from people who have completed the swaps. Makes it way easier to figure out what you need.

[crazy longhorn]

I set 1 up carbureted, I am a little "old school", but understand, that I have a 44yr old truck, with the stock harness(glass fuses), & still run the gen I stick shift? I will still run that stick, until my left foot falls off As everybody says, check around on the parts....get the best prices on used, or purchased for a project , but not used I don't have a bunch of money in my swap, but it cost some time? I opted for the edelbrock rpm package (intake,harness & controller). It was plug & play. The carb was a "hand me up", as my brother had a 600 edelbrock on the bench (just about new). A couple slaps on the loud peddle, to set the choke & give a shot....that 5.3 lites off quicker than my 02 Silverado! Do what you have the comfort zone for, if you have to pay the shop to do fuel system,electrical,ect, It will cost you some coin? Best of fun, Longhorn

[jstrong394]

Thanks for the post longhorn.... I have a grown up in dirt track racing so I have experienced dealing with carbs. I'm not into all the electronic stuff seems like a lot could go wrong and be hard to find the issue. Plus there are zero tuning shops around me. I'm hoping all I have to do after the cam swap spring and pushrod swap is install the motor and trans. Wire up the msd box and put a new fuel pump in and be ready to go after adding intake and carb? Is that correct? What about ac alternator radiator steering box? Will I need to find this stuff or will my old stuff off the 305 work

[crazy longhorn]

You are ok on the steering box, but will need the Ls style pump, as well as the brackets alternator, & ac compressor. The radiator will work, if in good shape....I run a 4 row copper /brass in my 69. However, if you need to replace the radiator(due to age), you might look into some of the aftermarket aluminum offerings? Some of the other guys here can help with suggestions on the radiator. Best of fun, Longhorn

[BR3W CITY]

Originally Posted by jstrong394

I'm not into all the electronic stuff seems like a lot could go wrong and be hard to find the issue. Plus there are zero tuning shops around me. I'm hoping all I have to do after the cam swap spring and pushrod swap is install the motor and trans. Wire up the msd box and put a new fuel pump in and be ready to go after adding intake and carb? Is that correct? What about ac alternator radiator steering box? Will I need to find this stuff or will my old stuff off the 305 work

The part in bold is just kind of a generalised assumption based on....what? There isn't that much that realistically goes wrong, and problems are usually rather simply to track down. Compared to vacuum based systems, constant carb tuning and adjustments (and the need to replacement hard parts to make said changes), and things like changing advance weights....efi seems logical.

ALL front accessories will need to be located from the same type of engine, there is no compatability with the SBC parts. You will need the AC (whole system), alternator, power steering pump and bracketry from the donor.

You can swap the fittings around to get the LS power steering pump to work with the oldschool steering gear.

Also for what its worth; you need a special MSD box to run this, not a regular 6al. It wasn't clear if you were buying a new one or trying to use something you had. And the 4l80e will need a computer to operate. Without it, you need a standalone controller which ain't cheap.

If you do stick with carbed, and decide to go with a th400....you DO end up with a semi-neutered LS engine. Without the overdrive you have to gear it to suit your driving habits...so either loses a little pep down low, or it runs screaming in the revs at 70mph (which also starts to remove it from the category of practical). Then you have to cam it and stall it to try and overlap a powerband that the truck can use...and that the carbed ls engine likes. Not to mention if there is a good change in temperature, humidity, or elevation, your guaranteed to be at less-than-optimal tune...at all times.

It might sound like I'm trying take the wind out of your project, but its not the case. Its just that all too often we hear the "I want an LS but I'm afraid of the wiring/electronics/tuning". Most of the time the reasons behind it are rather unjustified, and we watch people spend MORE for LESS technology, and break even on power. The only time I will advise this is if you have a bunch of leftover parts at little-to-no cost, and the only expense is the specialty parts like fitings and the msd box.... Under most other circumstances the cost just doesn't justify the end result.

[Wasted Income]

Well said, Brew.

[Special-Ed]

maybe i am biased, but i will take computer control and fuel injection over a stupid carb any day of the week.

i dont understand people logic... modern engines are so much easier to trouble shoot than past generations...

why are people so scared of fuel injection and computers... embrace the 21 century people! technology is simple people... if you can work a smart phone you can learn a modern computer controlled car.

i grew up on the cusp of carbs/fuel injection... if i never see another distributor or carb the rest of my life i will be happy!

there is another thread where the guy wants to get rid of the anti locks on his truck ... really just fix it right...uhg!

[jstrong394]

Dang I didn't want my post to turn into a debate between carb and efi. I'm set on going carb'd. I have the motor the carb the trans and the mind set that carb will fit my needs best. If I planned to drive the truck daily I would most definitely go fuel injected. And just for the record I'm not scared of all the electrical stuff. If I decide to spray a little I want have to find someone to tune it since the only real tune shop is over 2 hours away

[68GMCCustom]

My LSx was carb'd before injected....with racing in mind. I liked it and had it running pretty well. If it wasn't for my wife's complaints about the gas smell my truck left on you when you rode in it from the rich Holley 750 HP Street racing style carb it might still be. I had someone offer a stand alone harness, ecm/tcm, intake with injectors and throttle body...and an on-going tune for trade for something else I had....so I changed it to efi and sold off the carb stuff....which I should have held on to.

If things had happened differently my truck might still be carb'd. As far as t400....you could add a gear vendors OD instead of 4L80e... and wind up with a 6 speed.

[BigDan3131]

You don't have to use the 4l80E you can have a 200R4 built to handle the power you want to throw it no problem.

You will probably say the same things about my turbo carbed 5.3L that I'm nuts to not go the modern route. But when I look at all the wiring and mess of stuff on an engine it looks like **** plain and simple. Not only that but the motor looks out of place and small in the very large engine bay of our trucks. There are all kinds of ways around gas mileage and rpm by changing your gear ratio and running taller tires.
Pretty much anyone 30 and under unless they are in the automotive business have no idea how we ever ran a carb to begin with. My coils wont be mounted in the stock location and the less junk showing the better for me. A tall single plane and tall valve covers in bright Chevy orange with a huge turbo will be just fine compared to ugly plastic, sure you can paint it but it still looks like plastic regardless.

I have survived without a smartphone or laptop just fine but I bet YOU couldn't go a week without it or an ipad or any electronic device like that.

Sorry for the rant, kids just don't get it and never will.

[Wasted Income]

Originally Posted by BigDan3131

Sorry for the rant, kids just don't get it and never will.

LOL, (that mean's I'm laughing out loud...for the non tech savvy ) I could say same about you with EFI.


It's impossible to make turbo EFI engine bays look good...and with all the plastic!!

[BR3W CITY]

Setup for setup, I can make more power off the same displacement with EFI
/thread.

[68GMCCustom]

Originally Posted by BR3W CITY

Setup for setup, I can make more power off the same displacement with EFI
/thread.

then you're doing better then the gear heads at Hot Rod, Super Chevy, Car Craft and others that have run LSx motors in both carb and efi configs on a dyno with same cam, etc.......and while I agree an efi setup is better for a driver, mainly because its better in mid range and self-tuning during climate changes.......in their tests......the carb always made more "peak" horsepower. /

[crazy longhorn]

I have to jump back in here....I agree also, on a DD, the EFI is hands down On the track, you are using a very narrow band on the power? Tune the carb for the band you are running, & love that 2 step retard, for the shot,+ the rev limiter, & the laptop tunabilty on the ign curve. You can make em rock either way, just depends on what you want to tune/play with Longhorn

[BR3W CITY]

Originally Posted by 68GMCCustom

then you're doing better then the gear heads at Hot Rod, Super Chevy, Car Craft and others that have run LSx motors in both carb and efi configs on a dyno with same cam, etc.......and while I agree an efi setup is better for a driver, mainly because its better in mid range and self-tuning during climate changes.......in their tests......the carb always made more "peak" horsepower. /

I worked for their competitor....so ya f*** those guys. Lol
The issue is all about flow to make those numbers, as the carb will always lose out in fuel control. If you compare that same data with an EFI car running a 4150 TB and similar intake to the carb setup, I don't know that you would still see the disparity that they find.




*fun fact, about 85% of what you read in car mags is well....BS. IMO Engine Masters (iirc Randy is the man over there) is the only one that REALLY gets it done in terms of true engine building/data etc.
I can tell you about more than one mag that has straight up lied about the "results" of their builds. Same kind of mag has showed track results of like 10.20, but neglected to mention that their build chugged oil, blew its rings out on its third pass, and now sits in a warehouse covered in **** from other failed projects.

[68GMCCustom]

sweet looking but that just seems like sooo much overkill for the street tho. heck my truck even with large tires and just a n/a cam'd 6.0L... has traction issues. I'd imagine when the turbo's spool the tires just start frying...even at highway speeds. Gotta be fun tho!

[BR3W CITY]

Originally Posted by 68GMCCustom

seems like sooo much overkill for the street tho.

thats like blasphemy from a Texan! Any time I'm in the south, or the Big State, I run into more 600+hp street cars than should be allowed. I made like 420 at the crank, and I'm underpowered to mess around with street cars in TX.

[tinydb84]

Wasted Income those engines are damn sexy!