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73-87 Chevy _ GMC Trucks => Engine/Drivetrain => LT/LS Swaps => Topic started by: 78blackbeauty on July 07, 2010, 02:43:55 PM

Title: ls7 swap
Post by: 78blackbeauty on July 07, 2010, 02:43:55 PM
i wanna swap in an ls7 into my truck. i have a 78 gmc heavy half. shes blue right now but later on she will get a nice flat black paint job. the ls7 is a 427 out of the vette. idk how to do the swap all the way but its going to happen. info on this would help greatly. also idk how to post pics on here so help please
Title: Re: ls7 swap
Post by: Captkaos on July 08, 2010, 02:19:56 PM
LS7 is just a stout LS block, alot of people are swapping them in.  So any LS thread here will help you.  YOu can look in the tech section and the sticky at the top tells you how to post pics.
Title: Re: ls7 swap
Post by: 78blackbeauty on July 09, 2010, 11:22:41 AM
cool thanks
Title: Re: ls7 swap
Post by: Gandalf1969 on July 09, 2010, 11:44:47 AM
Plan, plan, plan.  It's tedious I know and I don't want to rain on your parade - it's an exciting project for sure.  But take the time to sit down and write a list of EVERYTHING else you will need to make this happen and be honest with yourself.  The swap from Gen1 to LSx has some considerations with $ attached.  Not impossible, just make sure you know what they are and how much you will be in by the time you are done.  You can safely figure 50%+ of the engine cost depending on how much you do yourself.  THEN add the "LS7 tax" - that's a beast by itself as not everything transfers over from other LSx platforms.  So even if you think your engine came "complete', consider what you will do for wiring, dry-sump (or even the cost of conversion to wet sump), fuel system, exhaust (incl O2), tuning, sump pan compatibility, radiator (different), a/c if you have that, accessories (mounting and wiring), trans compatibility (your existing won't work without modification and neither will the vette trans, sensors just to name a few.

That's all I can think of off the top of my head but from experience - figure even if you got a deal on the engine and "everything" from the vette, you may be up for the same cost again to get it in there and running.  Less if it's not LS7 because there's simply more parts and information out there.  So depending how much work you do yourself and what you have already, figure a super conservative $3k-$5k to get it in and running.

Talk with and listen to people who have ACTUALLY COMPLETED the conversion you are doing.  Mine is in a 69 Camaro so there are plenty of differences but the same principles apply.  Do your homework and there will be no surprises.

LS1tech.com is a great reference site for the engine side of things.  Good people there even though it's not a truck-focused site.


G.
Title: Re: ls7 swap
Post by: team39763 on July 12, 2010, 11:11:35 PM
Are you dead set on the LS7?  There's similar LS motors that can compete with the LS7 for less money and less hassle.  I had planned on doing the LS7 swap, but I think I can make that much or more power with less hassle by sticking with the more common motors....Like a LS3 stroked to either 418 or 427 with either a set of ported LS3 or LS7 heads. 
Title: Re: ls7 swap
Post by: 78blackbeauty on July 12, 2010, 11:16:19 PM
the reason i chose the ls7 is for the mpg and the hp. its 505 horses and about 20 to 30 mpg and its going into my daily driver. if you have any suggestions that will fit these guidelines, all is welcome
Title: Re: ls7 swap
Post by: Captkaos on July 12, 2010, 11:22:20 PM
Normally Aspirated, Boosted, Carb'd or EFI.
You can take a 6.0L LQ4 drop a cam in it and make almost 500hp at the crank.
Title: Re: ls7 swap
Post by: 78blackbeauty on July 12, 2010, 11:25:02 PM
efi and good mpg
Title: Re: ls7 swap
Post by: team39763 on July 13, 2010, 01:04:37 PM
I believe there's a guy on Tech that has a LS3 stroked to 418 with ported L92 heads and he's getting good gas mileage.  If I remember correctly he puts down 550+HP to the wheels.  I'll get more info on his combo and his contact info...he's a really cool/helpful guy.  LS7 just seems like an expensive hassle with all the not-so-common parts.
Title: Re: ls7 swap
Post by: 78blackbeauty on July 13, 2010, 03:46:07 PM
cool thanks. i want power but its for a daily driver so mpg is a big part. right now i get about 15 to 16 mpg but its not enough because i only work part time
Title: Re: ls7 swap
Post by: team39763 on July 14, 2010, 12:06:46 PM
The guy goes by WKMCD on LS1tech.  I think he just changed his setup though.  His old combo was a LS3 stroked to 416 with WCCH L92 heads and a small custom cam.
Title: Re: ls7 swap
Post by: Captkaos on July 14, 2010, 01:23:11 PM
Budget?  What is your current trans/gearing?

6.0L is the cheapest route to get to where you want to be.
Title: Re: ls7 swap
Post by: TexasRed on July 14, 2010, 01:32:30 PM
You don't have money for gas but you have money for a fairly intense swap?  ???
Title: Re: ls7 swap
Post by: Captkaos on July 14, 2010, 01:44:27 PM
yeah, read cheap as it is going to cost $2000 for and engine/trans combo with ECM, $400 for someone to go through the wiring extra junk ($600 for aftermarket plug/play), $400 new fuel lines, hoses, pump and sending unit.  $100 for mounting, $500 for headers, or manifolds with Exhaust, $400 for new exhaust, $400 for radiator.......

And when you are done you are probably going from 15mpg in the city to about 18 or 20....  The most I have seen out of a 73-87 with an LS (and the driver wanting to see the best mileage) is 25mpg driving 80% HIGHWAY and not more than 55mph..  Yeah 55mph.
Title: Re: ls7 swap
Post by: 78 Chevyrado on July 14, 2010, 06:35:20 PM
yeah, read cheap as it is going to cost $2000 for and engine/trans combo with ECM, $400 for someone to go through the wiring extra junk ($600 for aftermarket plug/play), $400 new fuel lines, hoses, pump and sending unit.  $100 for mounting, $500 for headers, or manifolds with Exhaust, $400 for new exhaust, $400 for radiator.......

And when you are done you are probably going from 15mpg in the city to about 18 or 20....  The most I have seen out of a 73-87 with an LS (and the driver wanting to see the best mileage) is 25mpg driving 80% HIGHWAY and not more than 55mph..  Yeah 55mph.


I can't drive, 55!  ;D
Title: Re: ls7 swap
Post by: team39763 on July 15, 2010, 10:29:19 AM
I bet the aerodynamics really bring the fuel mileage down.  The weight will likely be less than a NBS (new body style) truck though. 
   Capt is correct on those prices, but maybe you could find some deals and cut some corners.  I bought a NBS radiator for $50(it does the job). You can buy used headers or manifolds for $300 or less, the rest of the exhaust won't be too bad if you don't get too crazy.  I ended up with the $100+ mounts, but my original mounts were like $30-$40 and that same company(carshopinc) now makes more than one configuration.  As far as the fuel system, you may be able to shave a few bucks off(not much) by running your own aluminum hardlines($30 @ Summit) and maybe an external Walbro pump.
Title: Re: ls7 swap
Post by: Captkaos on July 15, 2010, 02:33:46 PM
I am not saying 100% highway of 25mpg it out of the question.  I would expect at least that for long trips.  My 305 got 22mpg on trips. (TBI) running about 62-65mph.

I am saying average is not going to be huge over the current 15mpg, maybe like 18 or 19mpg.
If you are looking for 25 in the city you are driving the wrong vehicle.
Title: Re: ls7 swap
Post by: 78blackbeauty on July 19, 2010, 11:50:34 AM
right now im saving for the swap. i have a job to get as and things but i need better mpg
Title: Re: ls7 swap
Post by: TexasRed on July 19, 2010, 12:26:45 PM
Why not a used car?
Title: Re: ls7 swap
Post by: 78 Chevyrado on July 19, 2010, 10:26:21 PM
15-16MPG is really good for these trucks....  Just save for your swap.  anything else you pour money into will be a waste, MPG-wise.  Bum rides from people all you can.  been there done that.
Title: Re: ls7 swap
Post by: 78blackbeauty on July 21, 2010, 01:47:25 PM
im trying to get a used car for now but theyre kinda pricey up front
Title: Re: ls7 swap
Post by: Gandalf1969 on July 21, 2010, 02:19:32 PM
im trying to get a used car for now but theyre kinda pricey up front

Did you read my recomendations about planning the swap?  No offense but I assert that anyone thinking about a used car being pricey up front or doing this swap to get better mileage has not thought the cost of the project through.  It's not like you can put the engine in and drive it while you do the other mods.  Cooling, fuel, electrics, (LS7) oil system.... all need to be done to even get the truck back on the road.  Think it through - you may find your used car money sitting on an engine stand in your garage :-)   Consider that these engines are only getting cheaper also.

And what team39763 said is completely on the money - another LSx swap can be had for much less and get the same (as stock LS7) much cheaper.  Again, selling your LS7 you may end up with enough for your used car AND an engine package for your swap.  Put in a stock LS1/2/3/6 for now - get the other mods done to run the truck.  THEN you can do heads, cam, intake etc etc down the road.  That gets you your swap much quicker, your used car for DD and all for much more reasonable money IMHO.

YMMV.
Title: Re: ls7 swap
Post by: frotosride on July 23, 2010, 09:34:37 PM
Ls7 is cool and all and does make a lot of power but as many have replied there is a big ls family that can do the same. My 1.5 cents...I've seen to many of those aluminum blocks cracked to ever want on in anything i want to punish..@ the last super chevy show there was one going for $400 except the huge chunk that was missing from #7 cylinder.. but hey it's your money.. like everyone has already told you plan, plan, plan....then do it some more. If you did wet sump would be easier to deal with and a little cheaper than buying all the dry sum parts in the long run.
Title: Re: ls7 swap
Post by: VileZambonie on July 24, 2010, 08:11:30 AM
You just don't build a 73-87 chevy truck for good gas mileage. It's a lose lose situation if you're looking at it from an economical standpoint. The cost to try to squeeze mpgs by doing a swap like this eats up the cost of the savings if there is any. An LS7 swap isn't going to save you any money that's for sure. If you need good mileage try this...

http://seattle.craigslist.org/skc/ctd/1857446732.html