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5.3 swap question

B

big pappa b

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haha..I'm first in the new forum :D

What involved in dropping a 5.3 in place of a 350? Specifically, I'm looking for mating the 5.3 to a SM465
 
I'm not sure about the manuals but there are some differences between the 350 block and the "LS" blocks in the bell-housing to crankshaft mounting surfaces. I was lucky enough to have Pac-Fab supply the correct flex plate to the TH 350 bolted up with minor torque converter hole work on the flex plate.

Seems like .400" comes to mind. For an Auto there is a specific Flex plate to use OR spacer and other specific flex plates to use. I would guess that you will find the same issues?

See if you can find a engine transmission combo that both the 350 and "LS" series used the same transmission. That would mean they built a Flywheel that mounted on the "LS" crank and accepted the transmission, the measurement difference between those flywheels would be what you need to have, I am guessing it might be as simple as a .400" spacer between the flywheel and crank.

You could call Pacific Fab and ask them, they have done enough swaps and are familiar with the older GM stuff as well.
 
Just buy the flywheel, starter, pilot bushing etc for a 4.8L with an NV3500. The input shaft length, size, spline count etc is the same as the one they used in the older trucks with a 350, 305, 4.3L etc. The bellhousing bolt pattern and size / depth is also the the same as the old trucks. The 4.8L stuff will bolt straight onto your 5.3L, which never came from the factory with a manual transmission. Buying 6.0L stuff also works, but some of them came with a long crank so things can get a bit confusing.

You will need to switch to a hydro clutch, but the good news is that the factory master cylinders for the SM465 trucks play quite nicely with the internal slave in the NV3500. I took and NV3500 from an 04 4.8L truck and bolted it up to a 6.2L diesel no problem using an SM465 flywheel, pressure plate and clutch disc with the 04 internal slave cylinder to actuate it.
 
I called Pacific Fab yesterday. They were very helpful. For anyone wanting to do a 5.3 swap, you should check out this deal. I believe he said a new 5.3 with new harness (correct for your swap and 3 wire hookup), and a reflashed computer for $2300.

This sounds better than the junkyard 5.3 for $1200 and would then need to get the computer done..another $200-300. Then having to deal with the harness

A different engine crossmember would either need to be fabbed or bought from them to clear the 5.3 oil pan --$300

They have a flywheel for the conversion. I believe he said $325 but Russel above said a 4.8 flywheel would work

:thinking::thinking:
 
Im going to bet that its not a "new" 5.3 with harness and computer for $2300. But, pretty much everything said above holds true. You will also need adapter motor mounts. Lots of ways of going about it but most will recoment the ones from Dirty Dingo.
 
I am running my 5.3 in front of a 465, I used advanced adapters flywheel. It comes with a spacer for the pilot bushing, then you just bolt up a standard k5 clutch and its good to go.

Harnesses are not that bad to make, it just takes some planning and time, I did my own harness for my swap and even integrated it with the bulk head connector so it was a true plug and play

You should be able to send your ECM out and get it tunes for $150 max, if you are just putting a stock 5.3 in the tuning is as simple as turning off vats and the codes for all the stuff that has been removed

Check out the link in my sig for more details on my swap
 
My biggest issue with Pacific Fab is that although they seem very knowledgeable, they seem to think there are more cross member conflicts than people are really finding.

They basically told me w/o a lift, i can't run anything but an 8.1.....
 
dhcomp said:
My biggest issue with Pacific Fab is that although they seem very knowledgeable, they seem to think there are more cross member conflicts than people are really finding.

They basically told me w/o a lift, i can't run anything but an 8.1.....
Click to expand...

I only had to do a small amount of grinding to fit the truck 5.3 pan into my truck. You could easily put this in a truck with no lift, Heck 2wd ck guys are putting LS engines in and they are lower and have a larger front cross member for the 2wd front suspension
 
I checked out your build thread and see that the crossmember and trans x-member were really no issue. Good to know.

Do you drive this on the street much? curious of the mpg your getting...assuming you stay off the whipple :whistle:
 
big pappa b said:
I checked out your build thread and see that the crossmember and trans x-member were really no issue. Good to know.

Do you drive this on the street much? curious of the mpg your getting...assuming you stay off the whipple :whistle:
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I put thousands of street miles on it with the stock 5.3, I could get mid to upper teens with the stock 5.3 and some tuning

With the whipple its a bit worse, I drove it 500 miles to silver lake last summer and got 12-13 mpg cruising at 75mph, the boost can really kill the mileage :D
 
I don't mean to thread jack, but I came across an 04 LM7 engine, harness computer, pedal, and fuel pump for 350 today and I bit. I just put a brand new flywheel on my current 86+ 350 with a 12 inch clutch. I found the bolts on my flywheel to be 3 inch diameter while the Ls series engines have 3.11 I'm wondering if you can't have a machine shop bore the holes a little and use the flywheel spacer and different pilot bushing of course

What say the brotherhood?
 
wheeler said:
I don't mean to thread jack, but I came across an 04 LM7 engine, harness computer, pedal, and fuel pump for 350 today and I bit. I just put a brand new flywheel on my current 86+ 350 with a 12 inch clutch. I found the bolts on my flywheel to be 3 inch diameter while the Ls series engines have 3.11 I'm wondering if you can't have a machine shop bore the holes a little and use the flywheel spacer and different pilot bushing of course

What say the brotherhood?
Click to expand...

That is a steal for the engine, Honestly for the fly wheel just get the right one and you will be able to use your new clutch
 
O I thought you had to use a smaller clutch. I am more than happy paying for a new flywheel if that all it takes (to get the trans hooked up of course). Thanks for the reply. Once again ck5 set me straight.
 
Definitely run the right flywheel or you'll have major vibration issues. The flywheels are matched to the LS engines for balance reasons.

The advance adapters kit really isn't a bad deal at all, and you know everything will work. You can definitely piece things together using factory GM parts, but there is honestly no need.
 
I've been searching around and seen a lot of people using an NFW1050 flywheel (55 bucks!) a replacement for the flywheel behind 4.8 or 6.0 vortecs with a 12 or 11 inch clutch. Btw the part can be found on eBay or at oreillys.
 
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