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Yeeeee Haaaaw!
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Discussion Starter · #1 ·
I have a perfect 400 small block sitting in my shop that I'm finally ready to build.
My plan is to bolt on some stock 5.7 heads for the newer (pre LS1) TBI system used in the late 80's and early 90's.
I have located a flash-burn style computer and harness that allows me to completely re-tune the PCM as needed with my laptop for any of the perameters I could possibly imagine and I know that I'll have to upgrade the fuel pump and pressure regulator and possibly even install a 454 throttle body and injectors to feed this monster.

I'm still undecided on what cam to use, but that's part of the reason I'm posting this here....
It will be installed in a 92 GMC Yukon 1500 4x4 with 4.56 gears ( i think) and 35's. Primarily street and sand use.
Any cam suggestions anyone has would bew appreciated and has anyone tried this combo yet? Anything that I really need to watch out for?

Thanks!
 

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Buy a Fiat! Save the UAW!
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well if you plan to do anything with this you should up grade your heads. stock head suck giant size. if you do some searching you can find a used set of Darts or Merlins. they are far better for mid range torque on demand. secondly I wouldn't get carried away on the cam. stay under 550 lift with 1:6 rockers and use about 270 intake duration and 276 ext. I think if you dig around Comp cams website you will find loads of good combos. what did you plane to use as an intake? that would make a big diff in how the power band responds. and as for the TBI if you find a `87-90 454 with Carb to TBI adaptor it bolts the stock 4bbl intake spread bore set ups. about the most you will have to do is use a good adjustable fuel regulator to dail it in.
 

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Buy a Fiat! Save the UAW!
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By the way, I was sitting here thinking about cams after this post. one of the draw backs on Chevy heads is the studs that are pressed into the heads. anything above 550 tends to rip out the studs. if you get Darts or merlins they would have screw in studs.
 

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this is the cam I used in mind.it's a Hyd Roller

Hyd. Hyd. 1500 to 5500 12-417-810 XM270HR 270 276 218 224 .495 .503 112°

And this is the cam that came in the 350 with TBI that was in the truck when I got it

Hyd. Hyd. 1000 to 5000 12-388-4 252AH-12 252 260 206 212 .425 .440 112°

But if you have a programmer I'd problem go with this one for driveibility and good VAC

Hyd. Hyd. 1500 to 5500 12-402-4 260AH-14 260 268 212 218 .444 .444 114°
 

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You probably already know this stuff, but it doesn’t hurt to bring it up just in case. Any heads need to have the steam holes to match those in the 400 block (or the heads can be drilled using a 400 head gasket as a guide). Also both the harmonic damper and flywheel or flex plate for the 400 crank are unbalanced. You can (or could in the old days) buy a counter weight plate that bolts between the crank and the flywheel which allows you to use any regular balanced sbc flywheel or flex plate. I might have one laying around somewhere you can have. Let me know if your interested and I’ll look for it. You’ll still need the 400 damper though.
 

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Yeeeee Haaaaw!
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Discussion Starter · #7 ·
Cool- Thanks guys! Yes I'm on top of the steam hole thing. I used to work for an engine re-builder, but that was back in the early 90's. Technology has changed so much since then that I wanted a little fresher perspective from some of you guys that live and breathe this stuff every day. I have the crank, rods, block, and the harmonic balancer and flexplate are on the way.
I have a Clay Smith solid cam brand new in the box, but I'll have to check the specs on it to make sure that it will work out.
As for the heads and intake, I love the idea of bolting on the 454 throttle body to a carberated style intake. That really opens up a ton of possibilities.
I'll see what I can dig up for other heads.
Origionally the truck had stock internals in the 5.7 motor with a bunch of bolt-ons with 3.42 hears and 33's and it did very well.
I'm just looking for a little more than it had back then and to keep it reliable. pump gas is also a must! I'm trying to be able to build this one and keep my Jeep.
 
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