L76 bored/stroked to 421 longterm build
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On The Tree
Joined: Apr 2015
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From: Bladenboro NC
L76 bored/stroked to 421 longterm build The 6.0 L76 in my G8 is making some ominous noises, sounds like it's knocking. I hate it but at least it gives me an opportunity to go thru the engine and do with it what I want.
I want to make this 6.0 into a 421 cubic inch engine (Pontiac 421 HO throwback). I plan to max the over bore to 4.030 and give it a 4.125 stroke to accomplish my goal. Will do my own port and polishing of the heads and upgrade to an LS9 set of valves. I may use a stock LS3 cam with 1.8 rockers not not 100% sure on the cam choice as of yet.
Right now, I'm just in the planning stage and will be slowely gathering parts I need to do the build.
I will start by pulling the engine out soon to make sure the block isn't trashed and can be bored and clearenced for the long stroke.
Also will be trying to keep this on a strick budget and will be doing all the work, minus machining, myself.
This isn't a lofty goal with this 6.0 block is it? Also if I can find a wrecked 5th gen Camaro SS, I'll use the LS3 for the base of the build. Just depends if I can get one or not.
The goal of the build is to have a stock looking, mostly stock sounding, stock driving G8 that the wife would feel comfortable driving. But when you want the power, it's there.
I want to make this 6.0 into a 421 cubic inch engine (Pontiac 421 HO throwback). I plan to max the over bore to 4.030 and give it a 4.125 stroke to accomplish my goal. Will do my own port and polishing of the heads and upgrade to an LS9 set of valves. I may use a stock LS3 cam with 1.8 rockers not not 100% sure on the cam choice as of yet.
Right now, I'm just in the planning stage and will be slowely gathering parts I need to do the build.
I will start by pulling the engine out soon to make sure the block isn't trashed and can be bored and clearenced for the long stroke.
Also will be trying to keep this on a strick budget and will be doing all the work, minus machining, myself.
This isn't a lofty goal with this 6.0 block is it? Also if I can find a wrecked 5th gen Camaro SS, I'll use the LS3 for the base of the build. Just depends if I can get one or not.
The goal of the build is to have a stock looking, mostly stock sounding, stock driving G8 that the wife would feel comfortable driving. But when you want the power, it's there.
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Joined: Apr 2017
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The correct pistons and engine build process will do well. 4.00 crank is even better not as much side load nor pulling pistons down as far. For most strokers 6.0 rod should be used to have a taller piston. Correct pistons and tapered bore is key.
*Oh if it's a aluminum block same thing goes sleeves are a hair longer. Diet Coke did a 430 Ls3 with the 4.125 crank. Did say a few things about he wouldn't have run it but rather a 4 inch crank. It can work just gotta have a competent short block builder. Most will recommend staying at 4 inches. 5.8 long sleeves help but add cost.
*Oh if it's a aluminum block same thing goes sleeves are a hair longer. Diet Coke did a 430 Ls3 with the 4.125 crank. Did say a few things about he wouldn't have run it but rather a 4 inch crank. It can work just gotta have a competent short block builder. Most will recommend staying at 4 inches. 5.8 long sleeves help but add cost.
Last edited by Patron; Sep 18, 2017 at 10:08 AM.
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6" rods are a bad too, not sure who you got that from but you must have misunderstood. A 6" rod is going to pull the pin down further in the bore for the same stroke, as well as cause the crank manufacturer to have to cam cut shorter counterweights, which could make it more difficult to balance. Most builders will use a 6.125" rod because it just makes more sense.
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KCS your correct on the wording for the bottom of the cylinder bores. But on a 6.0 rod that would make the piston pin move down some to not have it go into the rings. I noticed it on the Lsx 454 6.0 rods are used. Noticed a few other larger than 4 inch cranks using 6.0 rods.
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