Need help on rebuilding my l31 into a 383

[lxe4]

If you're looking at crate motors, Blueprint Engines puts together a pretty good 383 for less than a HT383. My TBI replacement 383 isn't wild by any means, but still puts out 280 HP / 400 TQ.

so you have done a 383 rebuild? how do you like it? was the jump in power output super noticable and mega kick ass? or kind of small and subtle? also what did you fuel economy do? big dump in mileage? im thinking of doing a 383 on my old 350 vortec, but im not sure if i want to have the fuel mileage any more

 

[Chewy1576]

so you have done a 383 rebuild? how do you like it? was the jump in power output super noticable and mega kick ass? or kind of small and subtle? also what did you fuel economy do? big dump in mileage? im thinking of doing a 383 on my old 350 vortec, but im not sure if i want to have the fuel mileage any more

My motor wasn’t a rebuild, it was a new crate motor from Blueprint. I love it, I tried to sell the truck but couldn’t find a buyer. I’m happy that I’m keeping it. It was a big difference in power immediately. 400 lb ft of torque will get you moving pretty quickly. I don’t think the mileage is much worse than a 350, 14-15 mpg I believe. It could be better because I play with it quite a bit. A Vortec engine has a better fuel injection system and much better heads so I think your mileage could benefit from that also.


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[94burbk1500]

So I don’t need to bore it to make it into 383 cubic inches???

The extra displacement comes from the longer stroke, if I put a 350 and a 383 right in front of you I doubt you could tell me which one is which.

 

[big_mike]

What makes it a vortec is the heads/injection system. You can still be considered a vortec motor as long as your running vortec heads.

If your not swapping intakes and it's a daily I'd honestly just run the 395 cam. It can be run with the stock tune, stock stall and it's not too much for the 4L60e trans. Same cam GM puts in the HT383 & 350 ramjet.

Look into upgrading the spider injectors to the MPFI unit. It'll be worth it with a new built engine going in. And honestly for the cost I'd also throw a new pump at it too. But that's just me.

Also look for a new distributor with a billet body and steel cam gear. Another upgrade worth the cost on a solid build.

 

[Bigredburb47]

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Okay fellas so I rebuilt my l31 almost back to stock got it up and running and driving around town like it’s nothing, but now my plans have changed and had bought a donor GMC Yukon XL denali and now just going to do an 6.0 LS swap into my suburban and just call it a day for now The 6.0 is currently in the machine shop getting refreshed and built

 

[Richard Jones]

What makes it a vortec is the heads/injection system. You can still be considered a vortec motor as long as your running vortec heads.

If your not swapping intakes and it's a daily I'd honestly just run the 395 cam. It can be run with the stock tune, stock stall and it's not too much for the 4L60e trans. Same cam GM puts in the HT383 & 350 ramjet.

Look into upgrading the spider injectors to the MPFI unit. It'll be worth it with a new built engine going in. And honestly for the cost I'd also throw a new pump at it too. But that's just me.

Also look for a new distributor with a billet body and steel cam gear. Another upgrade worth the cost on a solid build.

I am just about to start the process of either having a 383 built or buying a built bottom end. I have a 95 with the NV3500 fine speed transmission, my only worry is that the 383 is too much power for the trans. What do you think? I know people have done it before. I haven't purchased anything yet, but I saved the money and I'm ready to start next month, trying to get a list together of what all I will need.

 

[big_mike]

I am just about to start the process of either having a 383 built or buying a built bottom end. I have a 95 with the NV3500 fine speed transmission, my only worry is that the 383 is too much power for the trans. What do you think? I know people have done it before. I haven't purchased anything yet, but I saved the money and I'm ready to start next month, trying to get a list together of what all I will need.

Honestly I have zero experience with the 5 speed trans. I have only work on 6 speed T56's when it comes to manual trans. But if the standard rule of thumb for T56 vs 4L60 apply to the older auto vs manual trans then a stick should be stronger than a auto. If you don't offroad it hard or race it I don't see a stock 5 speed being a issue as long as you got a good clutch setup with it.

 

[Richard Jones]

Honestly I have zero experience with the 5 speed trans. I have only work on 6 speed T56's when it comes to manual trans. But if the standard rule of thumb for T56 vs 4L60 apply to the older auto vs manual trans then a stick should be stronger than a auto. If you don't offroad it hard or race it I don't see a stock 5 speed being a issue as long as you got a good clutch setup with it.

Yeah that's kinda what I thought. I'm gonna have fun in it but not beat it up. I'm gonna be too deep in it to do that lol. I believe it will last, the clutch will be new. So now just gotta figure out the motor part.

 

[Mrich0908]

The easiest way to do a 383 is buy a kit all pre balanced from a company. I used Skip White. Then buy a block machined from summit . It will have all the proper notching and suck from the stroker crank. Then you can just slap it all together in your garage and be done. You can see my thread here with my build a few years ago.
1 thing allot of people dont realize is when a company machines there pistons the tolerances are added into the pistons not the block. So all blocks bores will try to hit 4.030 exactly with the pistons being a few thenths .001 smaller than the goal. Thats why companys like summit sell already machined blocks with out the pistons.
You should be able to do a 383 bottom end with block on the cheap for 1200 I want to say. if you have any questions just ask.
www.theturboforums.com/threads/a-machinist-a-turbo-and-his-l31-gmc.381269

 

[Richard Jones]

I'll definitely read the thread at that link. I didn't think you could get even just a block from summit for $1200 and I think the bottom end parts average around $800-900. I'll look into it, would be an easier route