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Old 05-03-2021, 03:10 AM   #1
Cowboy13
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Engine swap

Ok guys I got a k20 70í chev with a tired ol 350. Swapping her out for somethin newer. What would be best to put in this girl. Iíve heard the LS engines are the way to go. Any suggestions are much appreciated. Thanks in advance.
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Old 05-03-2021, 07:01 AM   #2
Ol Blue K20
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Re: Engine swap

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Originally Posted by Cowboy13 View Post
Ok guys I got a k20 70í chev with a tired ol 350. Swapping her out for somethin newer. What would be best to put in this girl. Iíve heard the LS engines are the way to go. Any suggestions are much appreciated. Thanks in advance.
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The answer to your question is subjective. What's your budget? To me, the easiest is another small block. I decided on a big block in mine. Others like the LS. ...
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Old 05-03-2021, 08:11 AM   #3
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Re: Engine swap

i am always going to vote for the package crate deal (warranty), and 383 or bigger. but it all depends on your budget and what you are looking for.

if you want to go to a local machine shop and have them build your 350 at least stroke it out to get a good torque curve for the truck.

the LS route is a good option as well but the initial investment it still pricy to do the swap even with a junkyard donor engine,
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Old 05-03-2021, 08:15 AM   #4
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Re: Engine swap

What's your budget? Thats's the question . A lot of us "old guys" stick with what it came with , It's what we grew up with . If you want to drop an engine in and close the hood for the next year go LS .
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Old 05-03-2021, 08:28 AM   #5
BigBird05
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Re: Engine swap

I could build a full on drag engine for what an stock LS swap would cost. Do a cost analysis to see which way you can afford to go.
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Old 05-03-2021, 10:34 AM   #6
Davidf
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Re: Engine swap

I'm in the same boat. My 350 is tired and fouls the #7 plug after about 750 miles. I am not the only person that drives my truck because my entire family uses as a truck. So, I wanted something that is super reliable and easy to start, good a/c, good fuel economy, smooth, etc.

So, LS is the way I am going. I purchased my neighbors '01 Tahoe for $600. So far, I have pulled engine, degreased it, replaced lifters and resealed. Currently working on the wiring harness and planning location for ECM. It wont be long until I am ready to pull the old 350 out of the '71 and make the transplant. Super excited.
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Old 05-03-2021, 12:46 PM   #7
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Re: Engine swap

old school iron blocks are cool in my book.
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Old 05-03-2021, 07:35 PM   #8
Davidf
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Cool Re: Engine swap

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old school iron blocks are cool in my book.
I agree, thatís why I went with an iron block LS
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Old 05-03-2021, 08:00 PM   #9
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Re: Engine swap

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Originally Posted by Cowboy13 View Post
Ok guys I got a k20 70’ chev with a tired ol 350. Swapping her out for somethin newer. What would be best to put in this girl. I’ve heard the LS engines are the way to go. Any suggestions are much appreciated. Thanks in advance.
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I could be in error here so someone please correct me if I'm wrong about this, But it is my understanding that the 70 model trucks came from the factory sporting the engine mounts which can pull apart and cause the engine to rotate in the compartment, which then causes the solid linkage throttle to go wide open.

To change to the newer style mounts the frame needs a bit of editing at the mount locations because the 70 frames rails are an inch closer together than later models. I had the understanding that a half an inch would need to be cut from the upper rail on each side when going to the newer mounts to keep the same geometry.

Or this option, I suppose....http://67-72chevytrucks.com/vboard/s...ghlight=mounts

Do I have that right?

Last edited by Richard2112; 05-03-2021 at 10:18 PM.
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Old 05-03-2021, 09:17 PM   #10
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Re: Engine swap

Go with the 73 and newer clam style mounts.
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Old 05-03-2021, 10:04 PM   #11
jimijam00
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Re: Engine swap

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I agree, that’s why I went with an iron block LS
Sorry to hear that. Yours isn't in my cool book.
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Old 05-04-2021, 08:47 AM   #12
Davidf
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Re: Engine swap

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Originally Posted by jimijam00 View Post
Sorry to hear that. Yours isn't in my cool book.
That's ok, not trying to be cool. Just want reliability, drivability, smoothness, easy starting, smooth shifting, good fuel economy, and power.
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Old 05-04-2021, 09:14 AM   #13
72c20customcamper
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Re: Engine swap

Quote:
Originally Posted by Richard2112 View Post
I could be in error here so someone please correct me if I'm wrong about this, But it is my understanding that the 70 model trucks came from the factory sporting the engine mounts which can pull apart and cause the engine to rotate in the compartment, which then causes the solid linkage throttle to go wide open.

To change to the newer style mounts the frame needs a bit of editing at the mount locations because the 70 frames rails are an inch closer together than later models. I had the understanding that a half an inch would need to be cut from the upper rail on each side when going to the newer mounts to keep the same geometry.

Or this option, I suppose....http://67-72chevytrucks.com/vboard/s...ghlight=mounts

Do I have that right?
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Old 05-04-2021, 11:46 AM   #14
gmc684x4
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Re: Engine swap

Over 30 years I only had one factory engine mount fail and that was due to oil eating the rubber and forgetting to remove a bolt while swaping 350
When I had my first 67 72 truck on the road I spent better part of 15 years driving it like I stole it

Do you want fuel injection if yes go with an ls if no I would go with a l31 vortec engine
Tuning a ls is much better and it does have individual fuel injectors that can be upgraded the vortec has a injector spider assembly that limits hp it can handle
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Old 05-04-2021, 02:45 PM   #15
Bigdav160
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Re: Engine swap

I think you'll find the LS swap easier into a 2wd than a 4wd
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Old 05-04-2021, 04:47 PM   #16
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Re: Engine swap

Here is a members project that he put a ls into a 4x4 can be done without a lift and aftermarket front cross member

https://67-72chevytrucks.com/vboard/...d.php?t=389895
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