3.1/3X00 Hybrid basic install guide
Lets go over the parts you'll need from your donor 3X00 engine. You should try to source parts from either a 3400 or a '00+ 3100 for their flow ratings. The parts for '00+ 3100 engines are the same for 3400's so there is no benefit using 3400 parts over late model 3100's. If you choose to use parts from a '94-99 3100, they will still work, but you won't be using the best parts (i.e. get the most power) for the swap.
All parts are necessary for the swap unless otherwise noted. Gaskets for the new parts should be sourced based on the model/year of your donor engine unless noted. Parts are explained in more detail below, click on one to go right to it:
1. You'll need a set of 3X00 cylinder heads for your swap. They have larger ports and exhaust valves than your old 2.8/3.1. Get the valve covers with them. Make sure to get new head gaskets for *your old motor*, even if your using 3400 heads. 3100 gaskets are basically the same as 3.1 gaskets, but 3400 gaskets will not work because they have a larger opening for the increase cylinder bore. For important rocker arm and pushrod information see the FAQ here. (Question 13)
2. The second item on your list is the intake manifolds. You want both the upper and lower manifolds. They have larger ports and runners to increase flow. The lower intake manifold coolant pipe varies. The attachment of the pipe has two different styles. The older style uses a "nipple" coolant pipe attachment in the intake manifold. The other style of pipe slips into a machined hole and is held in place with a stud on the rear cylinder head. Make sure you get the appropriate pipe to match the lower intake manifold if you are piecing this together without a complete donor car or engine.
When using the stock style rocker arms and pushrod guide plates/rocker studs, or comp magnum roller rockers the intake gaskets need to have the pushrod guides trimmed off for the intake pushrods because they gets in the way. Just cut the 3 tabs on each gasket off to fix this. When using the larger ratio Comp rockers the exhaust side of the guide tabs must be removed to provide adequate clearance for the pushrods and rockers.
The lower intake gaskets are different between the 3100 and the 3400 engines, so get new gaskets to match your new parts. The upper plenum gaskets are also different between the 3100 and 3400 until '00 when the plenums started using the same style.
The top ends you'll want the most:
3400 Top end, and '00+ 3100 Engine top end. (either one will work the same)
3. You'll need a throttle cable to replace the one you have, because the 3X00 engines have the throttle linkage on the opposite side from the 2.8/3.1. A throttle cable from a '95 Beretta/Corsica has the right length, and works without needing to modify the firewall. GM P/N 22638838
4. You need to use the throttle body from your donor engine. If your intake didn't come with a throttle bracket or if your intake came out of anything but a car you need to get a bracket from a 3100/3400 style car. U van, Aztek, Rendezvous style brackets won't work.
5. Radiator Hoses. The 3X00 thermostat outlets are pointed in a different direction than the old 2.8/3.1 style. You'll need a different *upper* radiator hose that will fit it. The best style to get is a *lower* radiator hose from a '99 Montana. P/N GTR-61720 $10.69 from Summit Racing. That lower hose should fit your upper radiator outlet and t-stat housing without any modifications.
Alternatively a '99 Grand Am GT works as well. This hose has the right bends needed to make a good fit, but it is a little too long. You'll have to trim 2-3 inches off of each end, in order to make it work. It's important to only cut small amounts at a time, then test fit it for the proper size. If you cut too much, you'll need to to get another one.
The lower radiator hose on all 2.8's and some older 3.1's has issues with the new 3X00 timing chain cover. The older style was 1.5", while the new water pump inlet is 1.25" You'll need a hose from a '92-'94 V6 J.
6. The newer style '95+ EGR valves won't work with your stock ECM. If you have emissions testing in your state you will be required to attach an EGR valve to your plenum. Currently JBP offers an adapter for '95-'99 manifolds. If your using a '00+ engine, the EGR valve plenum port is different, and you will have to make your own adapter. Feavs (www.feavs.com) is the only person I have known to make one. Look towards the bottom of his page.
7. The old style 2.8/3.1 motors had the ignition coils directly under the front exhaust manifold. (yea, it's a very bad place to have them) The 3X00 have the ignition coils bolted to the backside of the intake plenum. The ignition module and coils are exactly same as your old ones, but the mounting bracket is different.You should get the new ignition module bracket and mounting studs. This relocates the module/coils up to the top of the engine like the 3X00 is setup. If you relocate, pull the wires from the harness, and lengthen as necessary If you relocating them elsewhere remember to keep your ignition module and coils mounted to a bracket, because it acts as a heatsink for the ignition module. Without one, your ignition module will burn up *very* quickly.
8. You have to get 3X00 exhaust manifolds as well. You new cylinder heads have a "d" shaped port that won't match with your old manifolds. It's best to use "short runner" manifolds, as these help flow and decrease back pressure compared to the old "log" style manifolds on earlier models. The gaskets used on the 3X00's have a heat shield built onto them. There is a problem with the front gasket heat shield because it gets in the way of the dipstick routing. Cut away part of the heat shielding off the gasket to allow room for the dipstick to route behind the manifold.The short runner type of manifolds require the use of a down pipe from the vehicle the manifolds came from. Your old stock downpipe won't bolt up. Since the outlet points directly at the firewall, you'll need to have the new downpipe modified to fit. You should tie up your shift cables, there have been reports of them sitting too close to the downpipe and getting burned.
9. You need to get the front timing cover from the 3X00 engine. Your old one will no longer fit with the new parts. You can get a new gasket for your old engine here, it will work with the new cover.
10. 3X00 engines use a map sensor mounted on the intake. If you want to relocate it there, you need to get the bracket for it and lengthen the harness. Stock or relocated, you need to get the MAP-Plenum-FPR hose. It's one piece.
11. You'll need a 3X00 Style fuel rail to fit on your new intake, but you should retain your old injectors. Multec 2 injectors that are used on 3X00 engines have compatibility issues with your stock ECM, and will run your engine *excessively* rich. Your old injectors fit on the new fuel rail without any problems, so use them. The fuel rail will have to be modified to allow connection to the stock body side pipe connections. This can be done with a set of steel "union" pipe connections 3/8ths for the supply line, and 5/16ths size for the return line. I believe they are also known as brass compression fittings. Do not over tighten them, it's just as bad as leaving them loose, test for leaks.
12. Steel power steering line. Since you have to use your old CS130 style alternator, and bracket, you'll need to get a different steel power steering line that runs from the pump to the pressure hose. The one that works best is from a ....... It has the right bends for a good fit around your old style alternator. Alternatively, you could rebend your own, but you run the risk of making it weak and having it break on you.
13. You absolutely need a 3X00 style power steering pump. Older 2.8/3.1 style pumps have a wider body and reservoir, and won't fit in the new timing cover. It's covered in more detail here. (Question 11)
14. The 3X00 engines use a single 3 wire CTS in the lower intake manifold. If you decide not to use it, you'll will have to drill and tap the rear cylinder head for your cluster gauge. Drill a hole in the same location as on the old Cylinder head. Use a 1/4 pipe thread tap to cut the threads. The other CTS goes in the lower intake manifold for the ECM. We are searching for vehicles that use the 3 wire sensor. A couple cars with them are the '00-'02 Buick Century, and the '93 2.2 MPFI Cavalier.
The 3 wire sensor
pins are:
A: Low reference
B: ECT sensor signal
C: ECT gauge sensor signal
15. Coolant hoses and pipes were changed year to year, and model to model. You need the water pump bypass pipe, and the appropriate intake manifold to heater core pipe. The front cover's water pump bypass hole has changed diameter and bolt hole location on the 3X00 engines. 3.1 engines had two bolts, and 3X00 engines only have one. For older J-bodies that used the heater core line along the passenger frame rail and across the back of the firewall, ditch this hose and use the new bypass pump hose. Your heater core hoses may not work with the new stock 3X00 parts. Some new bulk rubber hose will fix this. The 2.8 used a radiator cap on the filler neck above the water pump. 3X00 engines do not have a provision for this. You will *need* to get a reservoir with a radiator cap on it from a '92-'94 J body.
16. Ok, I decided to dump everything else here since they don't really require a lot of explanation. Most of the 3X00 sensors are the same and will work. However, even though stock MPFI sensors will work in the new parts, some rerouting/lengthening of harnesses will have to be done no mater which sensors you use. We recommend using your old sensors (except the CTS) because we know they work with your stock ECM without any problems. Any of your body side vacuum lines can attach to the plenum, it has plenty of vacuum ports. Some may need to be capped. You need the MAP-Plenum-FPR hose. It's one piece. The wiring for the map sensor will also have to be lengthened if you use the new style.
If there is anything that I missed, just let us know in the 660 forum, and I will be sure to add it here.