7.4L to 8.1 Swap?

[Kbirdjr]

Hey, sorry to dig up an old thread BT that’s what goggle does for us. How did this swap turn out? I did the same swap on my ‘99 K2500 last fall and still have a few unresolved issues.

 

[boredandstroked]

Why would anyone do this swap when you get just put a 4.25" stroke crank in with new pistons and have a 8.1L without any swapping or issues?

 

[Supercharged111]

Why would anyone do this swap when you get just put a 4.25" stroke crank in with new pistons and have a 8.1L without any swapping or issues?

Cuz an 8.1 with an Allison gets better economy than a 454 and it's an 8.1. Easy peasy to get the Allison in with the 8.1 too. And they breathe.

 

[454cid]

An 8.1l is a complete ready to go package. You're not done with a 454 just by putting a bigger crank in...plus no coil near plug.

 

[L31MaxExpress]

harness and engine take out, 411 swap

full 01-02 3500hd parts truck

they don make intakes and cams to run dizzys on an 8.1 but waste of money to revert back into technology.

theres probably a handful of other ways to do it if desired.

Dart makes one for a carb or TBI.

 

[lxe4]

Theres lots of ski boats and small/medium cudi cruisers came with the 8.1. Might have forged pistons and cranks in them too. Never took any apart myself but played around with some back in my old summer job in college. Seemed like a good plant

 

[92Raiderburban]

The heads will not bolt on there is no provision for a dist. In an 8.1. If your gona do it swap the whole engine everything is impoverished over the previous gen big block. Everything. Pass lock is easy to tune out that's not a big deal.

Are you sure about that? The Vortec 8.1 was GM's last engine they produced that will take an HEI when converted to carb.

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