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Old 02-05-2020, 12:07 AM   #1
seejohnrun
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L6 to V8 weight bias significance

Hello! I've swapping a 250 out for a 383, and I've been doing a lot of reading about the process for a long while.

I was planning on placing the engine in the original V8 spot because I don't want it to feel cramped, but from what I've read putting it in the L6 spot might give better weight bias and improved handling.

My question is: is this noticeable, and enough so that it's worth putting the engine further back? Or is it just a good reason to not move it if you're hoping to avoid the work.

Thank you for your time as always!
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Old 02-05-2020, 12:12 AM   #2
Steeveedee
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Re: L6 to V8 weight bias significance

Moving the V-8 forward might not be that advantageous, given that GM did it differently. What do you plan to do with your truck that makes that bias an advantage?
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Old 02-05-2020, 12:22 AM   #3
weim55
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Re: L6 to V8 weight bias significance

Unless you’re planning on using the truck for weekend road course duty or drag racing I would consider the positioning completely insignificant. I would simply go with whichever position makes the swap the easiest and most cost-effective.

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Old 02-05-2020, 07:06 AM   #4
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Re: L6 to V8 weight bias significance

The simple answer is "No". People didn't simply relocate the mounts forward where they need to be mostly because they didn't know any better. Didn't even know the engine was sitting back too far. All they knew is it dropped right in. Most didn't know the mounts were different either

Personally, I think it's silly to be concerned with such non-significant weight bias on a TRUCK. These aren't sports cars. Trucks are built to add weight to. AND, do people think the engineers at GM didn't know what they were doing? Why question what they did? PLUS... the reason the I6 mounts are farther back (just a couple inches) is because they are longer. So the weight is spread about the same, only a bit lighter with the six. Not that the truck will feel it. If you want a noticeable improvement in weight bias, move the engine to right behind the cab
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Last edited by special-K; 02-05-2020 at 07:13 AM.
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Old 02-05-2020, 10:01 AM   #5
seejohnrun
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Re: L6 to V8 weight bias significance

Awesome - thank you for the responses! I'm going to move the mounts forward then to the original location. Now to try to find a v8 manual trans cross-member
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Old 02-05-2020, 09:22 PM   #6
Mike C
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Re: L6 to V8 weight bias significance

I'd leave it the 6 cylinder spot. Save the money. Easier to bend the exhaust to rams horns manifolds, no need to relocate transmission, use same driveshaft. etc.
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Old 02-05-2020, 10:47 PM   #7
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Re: L6 to V8 weight bias significance

It's your truck so you decide which way to go . But when I did mine I had to switch everything to the V8 position and found the V8 manual trans cross member off the parts board from another member . I had to change mine because it would have driven me crazy (crazier) every time I opened the hood and saw the V8 sitting in the rear holes with it's distributor up against the firewall knowing that it's not the way V8 trucks came from Chevy . Yes it cost more and involves more work and parts but Gm did it that way and that's a good enough reason for me.In the pictures you can see the V8 cross member is heavier and how it sits further forward in the frame
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Old 02-06-2020, 08:55 AM   #8
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Re: L6 to V8 weight bias significance

If you own a 67-72 Chevy truck V8 and 4 wheel drive, the engine sits right up against the firewall just like it does when you mount it in the 6 cylinder position of a 2 wheel drive truck. So in that sense, yes, they were mounted that way form the factory.

I wouldn’t discount the effect of moving the motor back a little on performance would have either. Moving the battery from front to rear on a muscle car can have a noticeable effect on balance and traction. Moving 800# back 4” does make a noticeable difference depending on what you goals are.

4” less driveshaft can make a difference as well if you are running a 1 piece. Like everything else, it depends on what your goals are what might be best for you.

I am inherently cheap, and I don’t know what your plans are for transmission but I would change and spend as little as possible to do a GOOD, CLEAN, PROFESSIONAL looking installation.
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Old 02-06-2020, 09:28 AM   #9
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Re: L6 to V8 weight bias significance

I've driven these trucks with V8s in both positions and they all drive the same to me. But I don't do slalom. Figure GM used the same springs for small block and six. I'm keeping the apples with apples and oranges with oranges in my comparisons. I never noticed any difference in handling with dual batteries or aluminum heads either. Or driving alone vs with a passenger. The key word here is significant and that's what is generating my replies. That's why my simple answer is no. I understand the economics stand point and, honestly, either position is fine for me.

As far as oranges go, most of my experience has been with 4wds and the motor tucked back just that little bit makes it a PIA when it comes to the distributor. When I helped a friend put a 700r4 in his '67 Panel on a '72 Suburban K/10 chassis, the economical and way less labor way to go was the opposite. Move the engine forward. All pluses. Engine out of firewall, only move engine mounting, no transfer case crossmember moving, no floor mods (transfer case lever hole), and no altering two driveshafts.

But you never hear of people moving there engine forward in a 4wd to get it out of the firewall. Most likely because it's even more work and expense... AND, it's just no big deal either way.
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'67 C1500 Wideside Super Custom SWB: 327/M22/3.42 posi..........'The 67' (project)
'72 K2500 Wideside Sierra Custom Camper: 350/TH350/4.10 Power-Lok...'The 72' (rolling)
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R.I.P. ~ East Side Low Life ~ El Jay ~ 72BLUZ ~ Fasteddie69 ~ Ron586
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