1970 C10 LS Swap, 5.3 or 6.0?

[GACST10]

Hi all,

I am sure this has been discussed a number of times before but I have not been very successful at finding a straight answer to one question.

I am considering an LS swap on my 1970 CST10. I have read quite a few posts on the process. In many cases I see that the chassis has to be modified (trimmed) due to clearance issues with the LS and aftermarket headers. In many other cases I see that some end up with plenty of clearance without the need to trim or cut the chassis.

I do not want to have to trim my chassis when I do my swap. I am inclined to choose the 6.0 to get a little more power but if this engine size is the cause of the clearance issues that I have seen with other builds, I would rather stick to the 5.3.

Can someone help me understand the cons and pros specific to the clearances of these two engines with aftermarket headers? Does buying tubular engine mount brackets make any difference?

I appreciate your help.

[hugger6933]

There is no difference in the size externally between the two motors. The size is inside with larger crankshaft and pistons[bore and stroke] so if you can find a 6.0 close to the same money as a 5.3 get it. I sell my motors it seams on a sliding scale [or have been] 4.8's bring X 5.3's bring Y and 6.0's bring Z. The last loaded 4.8 meaning motor wiring PCM and trans brought $850 the last 5.3 sold "loaded" brought $1000 the last 6.0 was $1250. I don't know what they bring in your area but that is what I've got for some of mine. Jim

[hugger6933]

Those were just for comparison purposes. I am not trying to mess up anyone's sale. Jim

[DjS71]

Yep, zero difference in block size. Front accessory can vary but that will only get you into trouble if you want A/C and there are brackets to move the compressor up.

Hopefully you can find some of them Arkansas prices out here in California. They're pretty accurate, except apparently in Arkansas you get a trans thrown in for free


EDIT: If you get a 6.0/4L80, theres an ear on the transmission that has to be lopped off for headers, but that shouldn't slow you down too much. I don't believe the 4L60 has that issue.

[88Ironduke]

Be careful when looking at LS engines in the 5.3 arena. There was a thread in the LS forum a few weeks back on a guy who thought he bought a 5.3 and it turned out to be a 4.8. Visually identical, it seems the only true way to tell a 4.8 vs 5.3 is dished versus flat top pistons. Hopefully the LS gurus will chime with a few pointers on identification of the various blocks. Good luck.

88Ironduke

[davepl]

Last I looked the 5.3s were WAY cheaper than the 6.0s. If it were me I'd do a 5.3L swap, get it all running, and if the power wasn't enough look for a better motor. But the 5.3L is going to feel a lot better than, for example, a crate 350. Modern GM motors have an unofficial criteria of having something like 85% of peak torque available by 1800 rpm.

If you ever plan to have to rebuild it, look for max overbore tables first. The LS1 and LS6 and LS7, to my recollection, can not be bored. In fact that max hone is something like 0.003, and you could probably do that with a Scotchbrite by hand! Since sleeving can cost more than a new block, they are effectively disposable blocks.

There are half a dozen books, a thousand internet threads, and hundreds of parts available for this swap, so no shortage of knowledge out there. I hope to do one in my Camaro after this truck.

Again if it were me, I'd look for a complete takeout engine if you can. With the ECU, trans, and harness. Then get the harness cut down to what you actually need (no ABS, etc). A lot of more "modern" wreckers have those kinds of packages now.

[hugger6933]

You also want to stay away from the LM7 [I think is the rpo] from 07 to 09 5.3. The allure of the alloy block does seam sexy st first but I'm hearing lots of talk at the sales about the plastic roller lifter retainers failing and allowing the roller to turn in the block and we all know what happens when a roller lifter turns sideways in a block. It is crying time again. That is the main reason the motor is a lot higher than others[ is what I am hearing from salvage yard guys]You learn so much interesting and useful information at the sale if you just listen. That 5.3 is not much danger in making it into a project truck though as the price is way higher than all of its kinfolks like in the $3k range from what I'm hearing. the one before or after won't change and there is a stamping on the drivers side that will tell you the displacement. Sometimes down low on the block and sometimes it is on the pad behind the piston deck on the drivers side some times both. I am seeing these motors in the 400 to 500 thousand range more often at the sale [salvage pool ]with still viable sounding drive trains. I have personally sold some of a fleet of trucks I bought from our states largest dealers parts dept current to two year old trucks with 125 to 300 k miles on them Some I see on the road around town almost daily.

[bpatrol]

get a 5.3 its plenty strong and would have slightly better mileage.plus they are common and fairly inexpensive so its easier to pick and chose a nice one.
On another note you can bore the 5.3 to a 5.7 and just install ls1 pistons and have a 346.
6.0's are nice you are just going to pay probably twice as much.
p.s. put a small cam in a 5.3 and you will be more then satisfied.

god bless
bpatrol

[GACST10]

Thank you everyone for your input. I was mainly concern about the clearances issues with the engine and the chassis. It appears that the variation in clearances I have seen on other threads is mainly dependent on the type engine mounts and brackets used on the swap. I am planning to install the aftermarket engine mount brackets and engine mounts once I am ready for the swap. This is a restoration project I just started not long ago so, I am sure it will be a while before I am ready to drop in the new engine in the truck. I am planning to take care of the frame and suspension first... nothing fancy just power coating and new rubber all around. Then the body of the truck to get some little rust repairs and a complete paint job... and then after all that work, I would start looking into the engine.
As many people here, I have big plans but with a little budget and not a lot of spare time.

[no1udknow]

read this one :-)
http://www.hotrod.com/techarticles/h...g_bang_theory/