GM Crate Engine

1998_K1500_Sub

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So GM comes along with the idea of taking the displacement of the good ol' 5.7L out farther, digging into the aftermarket 383 market...but their production-line equipment isn't set up for 4.030 boring/honing. So getting an engine that can be marketed with the 383 recognition means using the standard 4" bore so the block can go down the normal machining line without tooling changes. Then they add a couple of cubes with a touch longer stroke. Given the GM buys heaps of them, it doesn't cost them any more to specify a 3.80 stroke instead of 3.75.

Price a GM 3.8" stroke crank. The aftermarket kills 'em with the more-common 3.75 stroke Chinese stuff.

Ah, so that's reason the GM "383" uses a slightly over-stroked 400cid crank... so they can continue to bore at 4". It's so obvious, I missed it.

So in my remarks earlier, i.e., "refurbish an L31", it makes sense to do the typical thing with .030 cut on the bores and a more common 3.75" stroke crank to get the 383cid.

It's worth mention that the 3.8" stroke crank in a .030-over block yields 388cid.
 

dyates99

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I wonder what it would cost to buy an L31 core from a yard, refurbish the block / heads and stuff the HT383e cam and stroker crank (3.8" stroke, longer than the 400's 3.75") inside...

Sounds like fun project.
Will definitely be fun. Ive been doing so much research lately and just ready to get the project rolling. Any insight or tips/tricks on yanking the old 5.7L out? I see some videos where people take off the whole front cap of the trucks. (radiators, grill, bumper) is all that necessary? I will only be pulling the engine, tranny is staying in.
 

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I remove the hood. Leave the fenders, bumper, rad support as-is.

You may/may not want to remove the rad itself. I usually do because I want it cleaned-out or replaced for the new engine. With the rad removed, you've got great access to the A/C condenser for cleaning/blowing debris out of the fins.

Support the trans while the engine is out. A floor-jack from underneath for short periods, other wise I use a length of mechanic's wire thru the bellhousing bolt holes, and wrapped around something sturdy on the firewall to hold the bellhousing end "up". Then the vehicle can be pushed outside somewhere out-of-the-way without having to wheel the floor jack along with the truck body/chassis.
 

1998_K1500_Sub

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Support the trans while the engine is out. A floor-jack from underneath for short periods, other wise I use a length of mechanic's wire thru the bellhousing bolt holes, and wrapped around something sturdy on the firewall to hold the bellhousing end "up".

Notably, don't support the transmission from the wiper motor or AC receiver-dryer :)

Seriously, another option, which I've used on my '79 Camaro, is to create a "saddle" with ratchet straps (or wire, scrap iron or what-have-you) between the frame rails to carry the transmission.
 
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Erik the Awful

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How can you use an engine intended for higher-GVWR vehicles in a low-GVWR truck? You'd be breaking the law because the low GVWR truck is overloaded.
Yup, those 4-bolt mains are really heavy. Honestly, I don't think a Chevy dealer will shorten your warranty for putting a 4-bolt engine in a 1500. That could be bad publicity.

That's a pretty nice price, but I notice they don't say if it's roller or flat tappet. I'd assume roller, being as it's spec'ed as a '98, but I'd call to make sure.

I see some videos where people take off the whole front cap of the trucks. (radiators, grill, bumper) is all that necessary?
Nope. Take off the front wheels and lower the nose of the truck until the rotors are just off the ground and you can clear the core support. I always remove the radiator. I'm paranoid that something will slip and punch a hole in it. Better safe than sorry.
 

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Take off the front wheels and lower the nose of the truck until the rotors are just off the ground and you can clear the core support.
Good point. I tend to lift the rear end with a floor jack then jackstands. Losing the front wheels would drop the front even more--but wait on that until the torque converter and lower bellhousing bolts are disconnected.
 

1998_K1500_Sub

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Take off the front wheels and lower the nose of the truck until the rotors are just off the ground and you can clear the core support.

I’ve built a “platform” around the front and sides using cinder blocks and 2x12s, to stand upon and make it easier to reach into the engine bay.
 

dyates99

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Yup, those 4-bolt mains are really heavy. Honestly, I don't think a Chevy dealer will shorten your warranty for putting a 4-bolt engine in a 1500. That could be bad publicity.


That's a pretty nice price, but I notice they don't say if it's roller or flat tappet. I'd assume roller, being as it's spec'ed as a '98, but I'd call to make sure.


Nope. Take off the front wheels and lower the nose of the truck until the rotors are just off the ground and you can clear the core support. I always remove the radiator. I'm paranoid that something will slip and punch a hole in it. Better safe than sorry.
Will be calling these guys on Monday. Any other good questions to ask them or things I would need to know?
 

dyates99

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Honestly from watching a few more videos, it’s seems like doing the extra work to take off the core support makes it a helluva lot easier to get inside there and have more working room
 

dyates99

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Does anybody know of a good forum or write up anywhere that shows the whole process and lists everything that needs to be disconnected from the engine for it to come out?
 
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