LS swap - what else will I need?

[hpcgmc]

I've decided to put a ls motor in my 67 GMC, mostly because I found a somewhat local engine supplier with a pretty good price.

Pacific Fabricators in Gilroy, CA has 4.8l motors for $1750 (5.3 for $2,500) They say most have under 100k miles. The engine comes with all accessories (ecu, a/c, power steering, fuel injection system, MAF, exhaust manifold, etc), they flash the ECU and they custom build a wiring harness for your application. They've got motor mounts adapter plates for $75 to mount to existing sbc motor mounts. Motor also comes with a 12 month warranty, they can usually tell you what model car it came out of and sometimes the mileage.

Since I'm not a fabricator, I like that they have sorted out alot of the issues, but want to know what I'm in for to minimize surprises.

I assume I'll need the following:
radiator/fan/shroud/hoses
modify or replace my existing exhaust pipes
fuel pump (I saw a post about a Walbro 255) - I will be using stock behind the seat fuel tank
wiring harness (I planned on replacing the entire truck wiring harness anyway)
gas pedal cable routing
clutch and flywheel (Pacific Fab quoted me $650)


What am I missing?
Where do you normally mount the ECU?
Is there a consensus on fuel pump for the stock tank?
Is there a consensus on a good gas pedal cable kit?
Is it worth an extra $750 for the 5.3?

Thanks!

[79c25]

From what I understand the 5.3 has roughly 30 more HP and torque than the 4.8. Dose that price include the transmission as well? That seems like a good price for most of what you need. For the throttle, I think some people have used a Lokar? kit.

[BR3W CITY]

Originally Posted by hpcgmc

clutch and flywheel (Pacific Fab quoted me $650)


What am I missing?

Is there a consensus on fuel pump for the stock tank?
Is there a consensus on a good gas pedal cable kit?
Is it worth an extra $750 for the 5.3?

Thanks!

Most of these are DBW now, unless you get something 99-early 03. The DBW doesn't use a cable or anything like that, the whole stock pedal comes out and gets replaced with an electronic unit that interfaces to something called a TAC, then to your ECM.

You can put the ECM wherever you want. Mine has been under hood near the headlight inlets, but is getting moved now that the inner fenders have been deleted.

I'd really consider ditching the stock tank. IMO its worth the money saving a few extra $$'s up and getting a fuel cell or similar option (blazer tank?) for between the rear frame rails. You move weight back, gain capacity, have easier wiring and access for the fuel sender, and its super easy to hook up return or returnless efi).

IMO those prices are high for an engine in general, but if it includes the trans than thats a bit better. I know cali can be a different situation, but out here 6.0' go for under $1200 in longblock form. $2500 for a 5.3 would be legit if they can gaurantee miles and include the trans, computer, DBW etc. Personally I'd take the time and put together the parts myself to save the $$. I didn't start knowing all this sh!t about LS motors, you just start doing it and you learn along the way.

[Matt Cramer]

Originally Posted by hpcgmc

I assume I'll need the following:
radiator/fan/shroud/hoses

You can use the stock radiator. I used 2005 Silverado 5.3 hoses - had to trim the lower one a little; the upper one was fine.

Does their setup include a clutch fan?

modify or replace my existing exhaust pipes

Find out what exhaust manifolds, if any, are included with that package. Truck manifolds are

fuel pump (I saw a post about a Walbro 255) - I will be using stock behind the seat fuel tank

That is what I'm running. It is a bit loud, though, and I'm considering an under-bed tank conversion. Just need to work out a good filler solution.

wiring harness

I thought you said they were supplying that? The rest of the

clutch and flywheel (Pacific Fab quoted me $650)

What transmission?

Is there a consensus on fuel pump for the stock tank?

I used a Walbro 255 lph pump with an installation kit intended for a 1990-1993 Mazda Miata. Fit in the stock tank on the end of the fuel sending unit just fine, but an in tank pump on an in cab tank is still rather loud, and I haven't fully banished fuel smells from the cab.

Is there a consensus on a good gas pedal cable kit?

If the motor comes with a cable operated throttle body, I used a mountain bike brake cable with a BMX style knarp end on the pedal side. Only cost about $12 from the local bike store and works great. Used the stock '72 gas pedal (not sure if a '67 has the cable type pedal or not).

[engairuph]

Just got mine running today, 69 suburban with a 2005 5.3 and went to the LS3 manifolds to trimming needed and plenty of room, used the factory radiator and 97-99 vortex radiator hose on top, fuel pump walbro and corvette fuel filter/regulator

[Liltroy]

I paid $1250 a couple weeks ago for my LQ4 6.0 complete with everythign except the MAF sensor. there are several 5.3 complete with transmission, ecu, and all accessories on craigslist right now for between $1100-$1500. I almost went that route but i just had to have the 6.0.