86 K5 Blazer Engine Swap
 

Hi Folks,

I will start off by saying I live in California, so smog is an issue. I want to swap in a 1996-1999 Vortec 350 engine into a 1986 K5 Blazer (it has stock 305). I will have to run all the smog equipment and the ECM to be legal here. Want to know if I will run into any problems with mounting the engine and if I will have to swap the transmission and transfer case as well. Any insight would help alot.

Thank you.

Vortec
 

You have a great idea. The fitment of the Vortec engine to your transmission would depend on if you have a manual or an automatic. If your transmission is an automatic and the motor your dropping in is from a manual vehicle you will have to replace the flywheel on the motor with a flexplate or or vise versa. 86 blazers are fitted with a block mounted mechanical fuel pump and 87 and above Chevy's have tank mounted high pressure pumps. So you will have to put in an in-line or in-tank electric fuel pump. If you are planning to carb the vehicle you will need to buy an aftermarket intake manifold because the intake to head bolt pattern is different on the Vortec motors, also note that you will need a low pressure pump for a carburetor. If you plan on using the stock fuel injection I cant really help you but I can say label all your wiring well. I hope I helped and good luck to you.

I'm doing this exact swap right now in my '85. The engine I have came out of a 99 tahoe. Both the donor vehicle and my Blazer are automatics. There shouldn't be any issues mounting the engine or getting it to mate up to the blazer transmission. As CS057 said you'll need to make sure you have the right flywheel or flex plate for your application.

A few notes about the 96-99 5.7... The stock vortec heads are fantastic but they do like to crack right around the water jacket in the center (both of mine were cracked and the machine shop that did my work had 4 or 5 pairs of them in the corner that also were all cracked, it's a common problem) The computer that controls it all also controls the 4L60E transmission in the donor vehicle so you'll have plenty of extra wires dangling around.

Painless makes a wiring harness to get this engine installed in whatever vehicle you want. I believe they also have reprogrammed PCM's to delete things like the VATS security. If you need the harness it's part number 60212. There's another harness you need for the emission controls part number 60320. You could also pick through the factory harness of the donor vehicle to save money.

As for the cylinder heads RHS makes a pretty good replacement vortec head (Pro-Torker, ~$470ish) there's also GM Performance parts stock replacements that are a little cheaper at about 300 each. There's also the Small Port Vortec Bowtie Head from GMPP for about $500 ish. Headsonly.com sells re-manufactured vortecs for 175 but those heads are all (or most) crack-repaired heads. Repairs are made by "pinning" it. Basically drilling and tapping a hole where the crack is, then running a threaded rod in to the hole and grinding it smooth. It's a good method for repairing cracked castings if the part won't be subjected to the same stresses that cracked it in the first place. I wouldn't trust it in this case though. Plus you can probably get your factory heads repaired for less than 175 if that's the way you want to go.

If there's anything I can do let me know I'd be glad to help.