five7kid

iTrader: (14)

This oft-asked question: What does it take to do the swap?

There is no simple answer. In fact, it would be nearly impossible to cover all the possibilities in one thread. But, here are the basics for putting a small block Chevy V8 into a car delivered with a V6 (or 4 cylinder, for that matter) from the factory.

1. Anything the V6 bolts to, and anything that bolts to the V6, will be different than the V8. Only possible exceptions are AC compressor (but the hoses and brackets will be different), alternator (early V6's were different, and again the brackets & wiring are different anyway), and power steering pump (guess what - the brackets & hoses are different).

2. Emissions-legal is harder and more involved than non-emissions legal.

3. It isn't "easy", "quick", or "simple". But, many of us have done it, so obviously it is possible. Follow general disassembly discipline; take pictures before and during disassembly, label everything as you take it apart, and it will be a lot easier to put back together..

4. A donor car that came from the factory with a V8 is the best way to get all that is needed to do the swap, whether or not you use the engine and/or transmission from the donor car. It's best if the donor is the same model (Camaro or Firebird) as the receptor car. It's also best if the donor car is at least the same year or newer than the receptor car (this is doubly true if the swap is to be emissions-legal). At this point, the simplest answer is, "Everything that's different between the V6 & V8 cars, change it." But, if you insist on knowing more details, keep reading.

5. The V6 rear end is as strong as a V8 rear end, because they are the same design. Only the ratio and/or posi/non-posi are different. Often, the V6 came with a more desireable ratio for performance than the V8's did. If you want posi, a PowerTrax can be installed with common hand tools. See the Tech Articles for beefing up the factory 10-bolt rear end for engines with higher horsepower than factory.

6. You may be able to use the radiator in your V6 car if the upper hose connection is on the driver's side and the lower connection is on the passenger side. Otherwise, get a V8 radiator.

7. Forget about using any of the factory-type V6 exhaust on the V8. This is a perfect opportunity to upgrade to headers and high flow cat on back. A good choice for aftermarket exhaust is '86-'90 TPI single cat application headers, cat, and cat-back, even if your swap doesn't match that description. Otherwise, use the donor car pieces.

8. If the transmission you are using didn't come from a 3rd or 4th gen f-body, you're going to need some means of mounting the torque arm. B&M makes a bracket that uses the tailshaft housing mount bolts. A good upgrade is a crossmember/torque arm kit from our site sponsor Spohn (see button above).
Side note: Transmissions from 4.3 liter Chevy V6's will mount to Chevy V8's.

9. The engine control module (ECM) from the V6 won't work. Use a V8 ECM. (You may be able to just change the PROM, depending upon the V6 & V8.) The V6 tachometer has a different resistance than the V8 tach. You can change the resistor, but it's typically easier to just get a V8 tach.

10. You may be able to modify the engine harness from the V6, but it's usually easier to get a donor harness. The harness will come out in one piece. Remove the plastic fender liner from the passenger side, and you can get acess to the pass-through grommet/connector. Unplug it (take off clip from the inside). In the engine compartment, I disconnected and labeled everything that went to the engine, and unbolted sensors that went to the car (again labeling where they came from). Then, the entire harness w/sensors can be lifted out from the car and installed in the receptor car.

11. The engine mounts are two pieces; one half bolts to the chassis cross-member, the other "clam shell" to the engine. The chassis half is available as a replacement from the dealer or aftermarket. Reports vary on the engine half - may be able to get from the dealer, may work from some truck models, etc. - best bet is to get them from a factory equiped 3rd gen V8. The chassis half is mounted to the rear-most holes for the V6, and the forward-most for the V8. Getting to the mount nuts inside the cross-member is easiest when the front A-arms are dropped, but figure on using a spring compressor if you go this route (see #13, below). Otherwise, figure on sockets/extension/u-joint/very small hands/lots of time/many colorful words getting to those nuts. The right/front brake line mounts to the front of the crossmember for the V6, right where the V8 mounts need to go. Either use the V8 factory line, or carefully bend the line to the rear of the crossmember after the mounts are removed from the V6 position. The p-clamp mount holes are there for the V8 position for this line. Side note: '82-'84 used SAE-type brake fittings, '85-up used metric.

12. If the V6 is fuel injected and you are putting in a carbed V8, the fuel pressure will need to be lowered using a 3-port (with return) adjustable fuel pressure regulator. Or, drop the fuel tank and remove the in-tank electric fuel pump. If you keep the electric pump, be smart and use an oil pressure safety switch. Depending upon the V6, you may have to rewire the in-tank pump when the ECM is disabled. Also, if you eliminate ECM control and have an overdrive auto tranny, you will have to make provision for the torque converter clutch lock-up.

13. If this car is intended to be driven on the street, use V8 front springs and sway bar. Otherwise, you'll be bottoming out the suspension regularly.

I will update this as appropriate/needed. If you have suggestions for changes, please PM or email me.