It’s time to start planning for a new drivetrain. I currently have a 350/th350, open 10 bolt w/2.73 gears. Fuel line is 5/16”, and I have the factory return (vapor line), not sure of the size.


I was convinced that I wanted a 454, so I bought a core motor, extra bare block, and extra heads for $500. I tore the motor down and put a price list together of machine work and parts to achieve about 450hp. This list also included all necessary parts to complete the swap. Well, it was more than $3,000 and I’m sure I missed something as all the little stuff adds up. I did not want to invest this much in the motor alone, so I sold everything and re-couped my money.


Now is seems like a no brainer to go LSX. The swap will probably cost more than the BBC, but money spent will not be wrapped up in engine alone (fuel system, etc).


OK, so the options are LM7, LQ4, LS1. Due to my tight budget, I think the LS1 would be last on the list. The iron stuff is only 65lbs more and HP is within 30HP worse case, and I plan to use the LS1 intake, rails, injectors, harness, and cam swap anyway.


I plan to use the F-body oil pan unmodified & accessories. I am OK with notching the x-member for AC. Engine placement will be dictated by “stock position” and will have to mate to the current th350.
If I were to go with a truck longblock, I would need to gather all the F-body parts. I figure a rough cost for all F-body accessories & brackets will run over $600, parts factored were a mix of new & used. The F-body oil pan & pick-up, harness, PCM, intake, rails, injectors, coil packs add up to another $700 – used parts. So the Q is, is piecing all this together cheaper than buying a LS1 from the get go?


Goals:

Use the th350 & current driveshaft
Use the factory AC with F-body compressor
400hp?
Headers that tuck up nice. Seems like hooker uncoated.
Later upgrade to 4L60E or T56. I know this impacts harness selection.

Budget is 3-4k.


Help me out here guys, my mind is all over the place…LOL.

 

go to the local wrecking yard and find a 6.0 truck engine ... plentiful and pretty cheap

I've seen a 5.3 w/ accessories and harness go for as little as 400

 

Yes, I agree. However, I don't recall reading about anyone using the truck accessories in a chevelle, and the harness/injectors have a different connection.

So, I'd have to buy F-body parts.

 

The truck harness and Accessories will work in your car, even with the LS1 intake and injectors, If you have the harness modded like i did, they changed the injector plugs for free. If you plan on modding the harness yourself just buy new injector plugs and install them yourself cheap.

A 6.0L will give you More than enough power. Add a cam and your well into the 400hp range. With the Chevelle you should have plenty of hood clearance for the Truck intake. I have seen them cleaned up and they dont look bad.

The truck intake performs better than an Ls1 Intake so you dont have to waste the money on it if you dont have to.

There is also a RetroLSX oil pan out there that should work fine as well. If you come accross F-body parts then thats good, if now there are other and for the most part cheaper ways.

 

The RetroLSX pan is now marketed by Holley....

The Truck intake will be close to the hood and might contact depending on how you mount your engine (height).

The Truck intake will have better performance on the lower end and mid range RPM wise. But they are butt ugly.. ! LOL. (i would really like to see a good dyno test between the two)

 

IIRC, that pan cost about $400? I'd rather use the F-body pan and pick-up which is ~$240 new.

Thanks for the tip on injector plugs.

What mileage would be considered too high when looking to buy?

 

wow i didnt realize that pan was soo much, i used the Muscle car Swap pan from GM, my car sits really low and so does my pan, im thinking of using big block springs to raise it a little. My pan only cost around 120 with pickup and windage tray. From the Dealership.

The Truck intake doesnt look pretty at all, but if your on a budget, it will get the job done all day until you can afford an upgrade.

Dont forget when upgrading to the LS1 intake with the Truck accy there is some issues with waterpump clearance and idler relocator needed. I spend atleast 1k buying my LS6 intake and making it fit. If money is tight then just hold off on the intake till later.

Its really hard to put a mileage limit on it. Depends on how the engine was cared for. These engines are good beyond 200k if well cared for.

 

I use them. Cheveythunder.com can make you a harness and program the comp to work with a 'dumb' transmission (which I also run, for now at least).

Just based on my own experience (1 swap) I would say unless the accessories are already on the engine just buy new ones. The code 'visa' at advance auto makes it about as cheap as buying used. I'm not a big fan of advance but I like saving money. Anyway, if I were to do it over I would just get a complete pullout or buy an wrecked z28 or ws6 and just drop the whole thing in there. Piecing stuff together sucks, is boring, expensive and a massive waste of time.
The truck intake isn't that bad, I prefer it to the car one actually, but to each their own. CTS-v oil pan works but hangs down a bit. Nothing bad enough to stop you from using it on a lowered car, but something to keep in mind when cruising around. The muscle car pan from GM is a truck pan (I think) that hangs down way more though. CTS-V pan will be more expensive, so you pick you battles.
Biggest problem with the truck stuff is messing with the power steering pulley. Again, nothing huge but worth being aware of.

 

Thanks for all the responses.

I do not want a pan that hangs below the x member. I've seen numerous swaps of the f-body pan in chevelle tucked up nice. My car is pretty low, here is a pic:

 

I used the F body pan on my 68 Chevelle. Engine is an LS2 w/ truck style accessories. I cut the rear side of my Cross member so I could move the engine forward and to have clearance for the pan. My pan sits 1/2" above my x member and the AC compressor is 1/2" forward of the x member. I would like to move it further forward but I'll wait until I get my 1 7/8" headers before I commit to that. PS pump needs to be moved with the truck accessories.







Tony

 

Truck accessories in a 72 442, with LS1 intake, truck injectors, aftermarket rail. I used the CTS-V pan and Kwik AC bracket.

 

Would there be any interference issues with stock AC box on firewall and engine placement in "stock" location?

Thanks for all the info and nice pics.

 

You are right about this one. I have the tendency to just buy stuff so it will keep me busy.

 

Gary,

Did you also use the Kwik alt/PS relocation kit? How did you address PS pulley clearance?

CTS-V pan users, how low does it hang below x-member?

Thanks.

 

I did a LQ4, F-body pan, Edelbrock mount plates, and hooker headers. Everything fit perfectly with no cutting of the cross-member. All I did was move the engine 3/4" back and re-drilled the cross-member engine bracket holes. There is probably an inch between the cross-member and the pan sump anyway.

For accessories; I used a new take off 'Vette LS3 water pump and P/S & Alt bracket I got cheap on ebay, used a cheap power-steering pump off a early 90's chevy car. I modified the truck alternator to fit the bracket and I got a vette harmonic balancer. Truck accessories would have worked, but I got deals on the vette stuff by looking around. The LS3 water pump has an outlet that was more toward the driver side, which allowed me to use a shorter upper hose. It was more of an appearance thing. I'm going to use a kwik bracket for AC when I install that this winter.

I also smoothed the truck intake and painted it. It actually looks pretty cool and clears the hood fine. I used a non return fuel line and LS2 injectors (which are good enough for the hot cam I'm running now).

 

I used holley pan and some real simple homemade brackets with a set of trailblazer manifolds,moved engine forward about 1 1/4" and was able to run factory truck ac compressor.

 

I kept the truck PS/alt bracket and cut off the idler pulley to clear the LS1 intake TB position and relocated it.
TThe CTS-V pan does hang below the crossmember maybe 3/4", but my car is not lowered and I'm not at all worried.
PS pulley is Dorman 300-201

 

My dorman 300-201 just shattered at random one day like the china plastic it is. A metal pulley would be a worthwhile investment, IMO of course.
The pulley you cut off, what did you mount it on when you moved it down low? I might take that belt routing approach.

 

Would you guys recommend me swapping in an engine or 12 bolt rear end first?

I have a 10 bolt 2.73 open right now. I guess if I wait then PCM will have to be tuned twice?

 

If the rearend works, engine first. When I had mine tuned I had it setup for 3.90's. A couple months after I had it running/driving I did the diff, gears and rear brakes. (Found out my 12 bolt had 2.56 gears; with the t56 it was like taking off in second gear every time). It was still fun smoking one tire for a little while.