question about a 5.3 install

[The Big Green]

What can this cost and what is everyone getting as far a gas mileage? I want to do this swap and have for a long time. How long does this swap take? Very hard or somewhat easy?

[Kid]

I put a 5.3 in my 51, after picking up your motor / trans, figure on at least another $1185 (Speartech) for custom harness & reworked computer (you supply the CP) & then the usual $450 or so for exhaust. I suggset you fab your own motor mounts so you can put the motor where you want. another $200 to $300 for fuel pump. If you have basic fab skills then its not a difficult instl. just fun. I'll never go back to the carbed small block for a driver. I haven't checked milage yet, but I will tomorrow on the way to Colorado Goodguys show. I am hoping for better than 20 MPG. I'll post my results when I get home.

[shifty]

There is a ton of information about that in this forum.

[GRIMSS]

here is one of the nicest 5.3 swaps I've seen in an older truck. this thing looks like my '01 under the hood.

[dan42]

wow, that guy did a very clean job on that conversion.

[Jtrux]

Absolutely, that looks great.

[The Big Green]

That truck is very nice and clean, thats what I want. My truck may never be that nice but atleast the engine will run good and keep the pg up a little higher than 12-14. I'm hoping with my new stock 350 it may get 16, the other number was with 11.1's, 305 comp, and 750 holley.

Kid
I'm sure the mpg will be a bit different on a 51 but it can get me a idea, shouldn't be much different if it is. I'm starting on a 49 and would love this swap on it also. With gas prices the swap will pay for itsself before long and we can keep this trucks on the road more, i'd love seeing more out around.

[shifty]

My post apparently got cut off early. This is approximately what I'd originally typed:

There is a ton of information about that in this forum.

A lot of members around here have done similar swaps, and MPG is going to vary based on whether you go carb'd or EFI, how your setup is tuned, whether you use a 4.8/5.3/5.7/6.0, whether you go for performance upgrades, what gear ratio and tire size you use, etc. etc.

http://67-72chevytrucks.com/vboard/s...86&postcount=5

That's a link to a recent post with links to other threads that members have created here showing their swaps, how they pulled it off, and i bet MPG is discussed there as well. General avg MPG from what I hear is 16-19 city and 20-26 highway on a mostly-stock engine. Even on carb'd setups, I have seen guys @ LS1tech say they're getting 14-16mpg in the city and 17-19 hwy.

[67ChevyRedneck]

Originally Posted by shifty

I have seen guys @ LS1tech say they're getting 14-16mpg in the city and 17-19 hwy.

I see these numbers as being reasonable. My silverado 4x4 gets 14/15 city and 18/19 highway.

Even so, these trucks may be lighter, but are still bricks. With a 3.73 rear end and a good tune I could see 15 city being reasonable as well as 20 highway, but 20 city, or even 20 for a mix of city/highway... well... my 2.2L 5 speed S-10 can barely pull off 21/22 city.... so...

My 67 with a 350/700r4/3.73 gets an honest 12.5-13mpg city and 16 maybe 17 highway depending on speed (60 can get about 17 while 80 drops it to 15 mpg.)

[piecesparts]

I talked to Mark Campbell from Street and Performance, not long ago, and he said that he and his people had put a LS-3 in a 96 Chevy truck and the owner was getting a good 22+ MPG (highway) from it. Granted the truck is slightly lighter than a mid seventies, but it was an extended cab and the LS-3 is a Gen III motor like the 5.3 motors. I have a LS-1 sitting in the frame of my 68, but have not gone far with it. As for motor mounts, there are many on the market, SOME will NOT clear the stock manifolds, but there are options on the market. I am going to use the tubular mounts from CPP.

[SCOTI]

Originally Posted by piecesparts

I talked to Mark Campbell from Street and Performance, not long ago, and he said that he and his people had put a LS-3 in a 96 Chevy truck and the owner was getting a good 22+ MPG (highway) from it. Granted the truck is slightly lighter than a mid seventies, but it was an extended cab and the LS-3 is a Gen III motor like the 5.3 motors. I have a LS-1 sitting in the frame of my 68, but have not gone far with it. As for motor mounts, there are many on the market, SOME will NOT clear the stock manifolds, but there are options on the market. I am going to use the tubular mounts from CPP.

I would be willing to bet 88-98 ECSB's weigh more than any 1/2 ton single cab 67-87 GM truck.

[piecesparts]

Originally Posted by SCOTI

I would be willing to bet 88-98 ECSB's weigh more than any 1/2 ton single cab 67-87 GM truck.

The sheet metal and frame construction of an 88+ truck is flimsy as hell compared to the earlier trucks. There is a good chance that there would be a reasonable match on the weight.

[1tigers]

i thought a 67-72 weighted about 1000 lbs. lighter. my 98 z-71is almost 7000 lbs.

[benwantland]

Originally Posted by 1tigers

i thought a 67-72 weighted about 1000 lbs. lighter. my 98 z-71is almost 7000 lbs.

I hope the old trucks are lighter! The GVW plate on my 70 C-10 LWB lists the GVW as 5000 lbs... in order for it to have anywhere near a "half-ton" payload, that means its dry weight has to be near 4000 lbs... Whereas my 92 F150 x-cab longbox 4x2 weighs 5200 lbs empty. Sorry for the ford reference...

[shifty]

the majority of people running GenIII + T56 + 3.73 gears are claiming 22-24 as a pretty common number with solid tuning an dno serious performance upgrades.

it's important to remember one thing here: most of us are installing these engines with free-flowing exhaust, no emissions equipment, and a better tune than the original car came from the factory with. so, i don't think it should be a surprise to see 5-6mpg more in this case.

just something to think about

[68 short step]

another clean install

[Sicmaro]

I found my 5.3l and 4L60E complete with harness, pcm, and drive line from a 04 Tahoe with 20k on them for $800. I found a set of Vette LS1 fans for free. I modded my own wiring harness. My old boss tunes LS based cars and trucks, do free tunes on the pcm. I used the stock exhaust manifolds. Spent $20 on craigslist for the flanges to bolt to the manifolds. cut and re-welded my factory exhaust system. made my own motor plates and used my factory mounts. Used the stock trans cross member and just re drilled holes in the frame. re-used the 71 radiator and factory tranny lines. used my stock gas tank. had the Tahoe one piece drive line cut down. I'm sure there is more. if you can be patience you can find deals on everything...... good luck