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Old 12-21-2011, 03:16 PM
BogiesAnnex1 BogiesAnnex1 is offline
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Originally Posted by thekcbeast
im trying to find out can a take a 5.7 vortec out of a 97 tahoe and put it in to my 87 suburban that is still set up for a tbi and what would i have to do ?
You will need the 87 distributor which is alot different from the 97 Vortec. So that just carries over from the 87, it fits into the 97 just fine. If there is an issue it will be with the drive gear where the 87 used a cast iron flat tappet cam the 97 uses a roller. OEM roller cams are a cast steel which may be incompatible with the older distributor. I'm squishy here only because GM tried different solutions at different times but the safest thing to do is get the Melonized gear from GM for the 96 and up Vortec engine or use the one from the Vortec if it isn't worn through the surface hardening.

You will not need the crank position sensor on the front timing cover, it just is left alone, not hooked up.

The intake is the biggest problem, the heads have a different bolt pattern between 87 and 97 so the TBI intake doesn't simply bolt to the 97 heads. Also the Vortec heads do not have an exhaust heat source to warm the intake and supply the EGR. A simple solution would be to rebuild the 87 heads and put them on the 97, that completely gets around the intake fit and EGR exhaust source problems. This combination would continue to use the 97's push rods which are shorter than the 87s to make up for the taller roller lifters in the 97 block.

If you use the 97 heads then you've got to use an aftermarket Vortec to 4 barrel intake with TBI adapter or the GMPP Vortec to TBI which is a damned pricey but a lot simpler solution, especially where the EGR is concerned. If you don't need to pass an emissions test you could get by without the EGR, but that will cause the mixture to be lean in the zones where EGR functions which will cause surging, back firing, and detonation, though because of the detonation sensor you may not be aware of it, but the automatically retarded timing will reduce performance and increase fuel consumption. To regain the proper mixtures at the proper times would require a custom computer chip, this is about as expensive as GMPP's golden manifold. The GMPP intake uses an external exhaust supply to the intake, all of this is over the counter GM parts, consisting of a left side exhaust manifold with an adapter pipe that feeds the intake's hot spot and EGR. Much of this system is on your 97 engine.

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