Chevy & GMC Vans

Ok so lets start from the beginning. I have a Chevy Silverado 1500 with a 4.8 and 4L60E. Now this truck has LOTS of value to me. It was my fathers then when he passed away it went to my little brother, when he passed my mom gave it to me. So I have had for the past few months and have been kicking around idea's on what and how to fix it up a bit in both of thier memories. Lowering kit, <2wd btw> engine upgrades etc.

Now here is where I need help. I have an older 80's model 350 bored .30 over, flat top forged pistons, sitin about 9.5to1 comp, .485 lift int/ext. Now I've had this engine and was thinking about getin a set of vortec heads for better flow and dropin it in a play toy. Then it hits me like a Mack truck..... take the block out of the 2000 and drop it in there!! Now I know I will need to reprogram the comp on the truck, thinking about putin in a new roller cam.
So what I am wondering is, will the older block bolt up to the 4L60E. I am fairly certain that I will need to fab up some motor mounts as I think they chaged how the engine bolts into the trucks. SO anybody try this or have any info on it? I know there are more than a few changes like the fuel pump block off and figureing out how the accessories to the block.
Also I have a lap top that I wouldnt mind tryin to find the software to mod the trucks PC myself. O and I put this in off topic because its not an Astro/Safari so if a mod wants to move it somewhere else please do.

I say drop the 350 in the van and throw a 6.0L/4L80E combo in the 1500.

The tranny will need a $1k controller, the dash gauges probably won't work right without all the original PCM being functional and going back to a carb seems like a step back to me. The 4.8L is an LS based engine so yeah the mounts won't work and none of the accessories will bolt up without fabbing your own brackets.

Wait a minute...I had a 99 Silverado with the 4.3/4L60E combo. It was also a 2WD truck. If you can get the motor mounts from a 4.3 equipped truck it would probably work for you. Hmmmm...

See I was going to reuse the entire top half of the engine, heads intake all sensors etc. the PC needs to be flashed to make it reconize the extra cubes and HP. My biggest question is, will an LS based tranny bolt to an older block. Well 3 probelms really, will the tranny bolt, makeing a serpentine belt system work on older block and reprograming the PC. I was looking at a new Jet chip anyway so the cost for that isnt a big deal its the rest.

As for the mounts off a 4.3 I never thought of that!! That would save me some serious time if I can just mod them instead of fabing the whole thing. I have a garage with just about every tool I need but a Tig welder and a plasma cutter <have a stick and Mig welder with any tool you can think of as my dad was a mech also =) > So ya any other ideas of bits of info is REALLY helpfull thanks guys!!

Hotroder383 wrote:See I was going to reuse the entire top half of the engine, heads intake all sensors etc. the PC needs to be flashed to make it reconize the extra cubes and HP.

I need clarification...you want to use the heads, intake, sensors and fuel injection from the 4.8L and bolt them to the 350 block? If this is the case, the PC flash will be the easy part. I highly doubt you can bolt a set of 4.8 or 5.3 heads to a 350 block. Also the tranny bolt patterns are not exactly the same. I think there will be 1 or 2 bolts that are either off or not used.

Yes reuse the everything BUT the short block. I know the sell "Vortec" heads for older engines like mine but what I dont know is if the 4.8/5.3 family of heads is what they use. and if there is a differnce in bolt patterns on the tranny that stops the project right off, unless it is only one bolt outa 12 that wont match. I dont think I'd feel safe running around with only half the bolts holding the motor and tranny together LOL

Short answer is no.
The 2 engines you are talking about have virtually nothing interchangeable with them. The tranny bolt pattern is different. The engine mounts will not line up. The heads, block, intake etc. are all very different. 2 different series of engines.

Yes, I found out after some more research on the net that the "Vortec" heads you buy for the older blocks are different then what I have. On the upside I have found several rebuildable 6.0 LS engines for under $500 so I will probebly go that route with the Truck. Thanks for the info though guys!!