2QuickNovas.com - Chevy Intake Manifold Swaps

Intake Manifold Swaps

Please forgive me if this is too detailed for your experience level (or if I inadvertently left something out)!

First, buy a box of Ziploc type sandwich bags and a black marker. Everytime you remove a bolt or clamp or bracket, put it in a bag and write on the bag what it is. There are many bolts and brackets you'll be removing and when it comes time for reassembly they'll all start to look alike.

Drain enough coolant to get the level below the heads. Remove upper radiator hose.

Remove thermostat housing and thermostat. Label all vacuum lines, hoses, wires, cables, etc. in order to get them hooked back up properly. Don't label with pencil as it might not be legible when its time to reassemble.

Remove air cleaner, carb and any brackets that bolt to the intake.

Remove the heater hose and hose fitting from the intake. This would be a bear of a job to do with the intake unbolted.

Turn the motor to TDC for cylinder #1 (mark on harmonic dampener will line up with zero on the timing tab).

Remove distributor cap. The rotor will either be pointing at the #1 or the #6 terminal of the cap (doesn't really matter which).

Using some chalk, mark on the body of the distributor directly below the tip of the rotor so that you know which way the rotor was pointing. Also make a mark on the firewall corresponding to the direction the rotor is pointing.

Remove the coil wire from the cap (if its a points distributor), the vacuum advance line and the wires from the coil after marking them for reassembly.

Loosen (you don't have to totally remove the bolt) the distributor hold down clamp and pull the distributor up and out of the motor. The rotor will turn when you do this. Make a third chalk mark to note where the rotor turned to when you removed it.

Put the distributor in a clean plastic bag so it stays clean.

Remove any other lines, hoses, brackets, the coil, throttle cable, kickdown cable from the intake being sure you labeled everything.

Removal of the valve covers may be necessary, but isn't always. If the intake won't lift off with them installed, you'll have to remove them. I've found no need to remove them when using stock valve covers.

A 9/16" wrench/socket will be needed to remove the intake bolts. Start on the ends and spiral toward the middle. This avoids the possibility of cracking the intake. Here is the pattern I use:

Passenger side
1 5 12 9 6 2

4 8 11 10 7 3
Drivers side

It doesn't really matter which side you start on as long as you use a similar pattern.

More than likely you'll have to pry the intake loose once the bolts are removed. A long screw driver under the front edge usually works for me. At times I've given the intake a few light whacks with a small sledge to loosen it up. Just don't get wild with hammer or gouge any surfaces with the screwdriver.

At this point, you should be ready to lift off the old intake. Its weighs about 25 lbs. if its a stock iron manifold, so lift with the health of your back in mind. 25lb. isn't that much, but you will be bent over while lifting which isn't good.

Hopefully not too much anti-freeze spilled into the block. If it did, drain the oil so that the anti-freeze doesn't attack your bearings. If none leaked into the bottom end, don't worry about draining your oil now. But you'll need to change the oil before starting the engine.

I like to put lots of paper towels in the lifter valley and in the intake ports to keep any junk out of the bottom end of the motor. Supposedly paper towel is soluble in motor oil where a cloth fiber is not, which could possibly scar a bearing.

Thoroughly scrape all gaskets and I like to wipe the surfaces down with lacquer thinner to get any oil off them. Once you are finished scraping and cleaning, remove all the paper towels (don't forget the ones in the intake ports) and clean up any trash that fell into the lifter valley, intake ports, etc.

Clean the new intake inside and out. This will usually just entail blowing a little dust off or other such small stuff. At this time, go ahead and clean up the intake bolts. They most likely will be a little "gunky". A wire brush usually does a pretty good job. For what they cost, I'd about rather buy new bolts. They'll look great and you won't have any pesky wire pricks on your fingers.

You are now ready to put this engine back together. Run a small amount of sealant around the water ports on the heads and put the side intake gaskets on, making sure all the ports and bolt holes line up. Take the little end gaskets and throw them at any stray dogs or cats that you don't want around. Put some more sealer on the intake side of the gaskets at the water ports. Run about a 1/8"-3/16" bead of sealer across each end making sure to overlap with the gaskets. Put a little extra in all four corners. Let the sealer skin over for a few minutes. While waiting, make sure the new intake is still clean and ready to bolt on.

When setting on the new intake, make sure you set it straight down, as you don't want to move the gaskets or smear the end beads of sealer too much.

A helper is handy at this point to help guide you. Once the intake is sitting on the motor, you're ready to put clean bolts in. Put a dab of thread sealer on each bolt and barely snug them up, but don't torque them. You are now ready to torque them in reverse order of how you removed them.

Passenger side
11 7 3 2 6 10

12 8 4 1 5 9
Drivers side

Torque them to 10 ft-lbs on the first go around, 20 on the second, and 25 ft-lbs on the third pass. Keep going around until all 12 bolts are torqued to 25 ft-lbs (some bolts will lose tension as the others are torqued so you must keep torquing them multiple times), or whatever value the instructions with your new intake call for.

Everything else pretty much goes back on in the reverse order. There will be obstacles to tackle to make the new carb work. Its hard to predict what those will be. Possible problems will be the throttle cable lengths, kickdown cable length, choke mechanism, etc. Hopefully those will be fairly straight forward to fix.

To get the distributor back in, hold the distributor over the hole in the intake. Rotate the shaft until the rotor points at the mark on the firewall AND lines up with the "as installed" mark on the distributor housing. Now rotate the shaft to line up with the other mark. Slide the distributor into the motor. As the gear on the distributor meshes with the gear on the cam, the shaft will rotate and should end up lining up with the "as installed" chalk mark. Be sure that the distributor sits all the way down on the intake. If it doesn't, the tang on the end of the distributor shaft didn't line up with the groove in the oil pump shaft. If this happens (and all chalk marks are lined up), you can turn the motor over and when the tang and the groove line up, the distributor should fall into place. I suggest turning the motor by hand when doing this, but some use the starter motor.

Finish up hooking up any wiring , hoses, cables, brackets, etc. Change the oil and pre-adjust the carb per any instructions included in the carb.

If the distributor went back in correctly, the motor should fire as soon as gas gets to the carb. The carb can be primed to speed this along by pouring a small amount of gas down the bowl vent tube. Just don't flood it over. I'd probably just let the fuel pump do it for you as you crank the engine over. It shouldn't take it long to prime.

If you have a timing light, I'd check the advance once its started. With the vacuum advance line removed and plugged, you are shooting for about 8-10 degrees initial advance. Your year of car may specify a different amount of advance though. Don't forget to hook the vacuum advance back up after you've set the timing.

The carb will probably run fine out of the box, but you may want to play with the idle screws a little bit. Turn them in until the motor stumbles and the back off a little (note, some carbs are leaned out as the screws are backed out). Somewhere near 1 to 1 1/2 turns from LIGHTLY bottomed is a good ball park setting. You also probably need to adjust the idle speed. Do this with the motor idling in gear with the wheels blocked and the parking brake set. Don't take any chance while doing this. It can be done with the car in park. Just realize that the idle will fall some when its dropped into gear. So the idle in park will be a little higher. It should idle just fine if you set the idle in park speed at about 700-800 rpm.

If you have any questions or comments please click the "Contact Craig" link and let him know.