GM A-Body Instructions

 

Header Applications

INSTRUCTIONS FOR ALL '64-77 GM A-BODY SYSTEMS:

Included with this kit are the following:

▶ NOTE: While we have made every effort to design this system to fit most applications of the A-Body vehicles, we cannot allow for every single variation without raising the price considerably. We know that from time to time situations will arise which will not be accounted for. To help minimize inconvenience to you, we recommend that you do some measuring, etc., before "tearing off" the old system. This way, if you have one of the exceptions, you will not have "down time" if your vehicle is a daily driver. This will enable you to obtain the necessary parts to complete the installation.

▶ NOTE: The 3" Tailpipes on 73-77 Vehicles will be extremely "tight" between the upper control arm and coil spring. You may find it necessary to dent the tubing somewhat in that area much like is done with headers at times. On one installation, we found it necessary to move the fuel tank back by "re-shaping" the tank mounting straps.

▶ Muffler length is generally limited to a maximum of 20" case length. Both Walker and Flowmaster muffles work equally well, however, the mufflers used need to be offset entrance and offset exit. A center exit sometimes can be made to work, but the tailpipe alignment will be less than ideal.

INSTALLATION:

1. First, be sure to read through the Thank You and Caution Flyer accompanying these instructions.

2. Secondly, read these instructions throughout to get a good overview.

3. Thirdly, remember, safety first. Be sure vehicle is secure and remember that pipes can cut (fingers & hands).

4. Now, compare hardware with the list above to be sure you have everything before beginning. NOTE: To help prevent rust on hardware, you may want to paint all exposed metal before installing. Beginning Mar 15, 2001 all Nuts, Bolts, etc. will be Stainless and all Clamps will be Zinc Coated.

5. Begin by mounting Collector Reducers on end of Headers. You may want to note now if your headers seem to be pointing straight back. IF one or both aren't, they will present problems when it comes time to install the Head Pipes later. IF you're not sure, then you can temporarily mount the Headpipes onto the reducers and see how they do.

· If a Headpipe wants to cross over into the driveshaft, then this is telling you the header is pointing inward.

· If the Headpipe wants to point outward away from the center of the vehicle as it goes back toward the muffler, then this is telling you the header is pointing outward.

The header could even be pointing downward or upward. The Head Pipes are designed so as to allow you to compensate for some error, but if it is much, then you will be faced with adapting. Our "No-Weld" Collector Reducers can often help. Sometimes it will take more than this. If you are not sure, give our Tech Dept a call. We can offer suggestions if you can tell us exactly what is happening. See note at end of Instructions.

6. Now lets begin with the tailpipes. They must clear the suspension and the rear end, so they must be positioned first. In some situations it may be possible to use existing hangers, otherwise use what is provided with the kit. You will need to position the hangers for the mufflers directly above the rear of the muffler spout. This will be on the cross-piece from one frame rail to the other. There may be existing holes there or you may have to drill new ones. The hangers for the end of the tailpipe can be placed anywhere along the outside of the frame. Often existing holes can be used, but you may need to drill new ones. If you have two-piece tailpipes, you might want to add the end piece last, but if possible mount the rear tailpipe hanger assembly at the end of the pipe. This way when you mount the last section of the tailpipe, you can use the same clamp. This will allow a cleaner looking installation.

7. Mount the muffler onto the front of the tailpipe. You may want to temporarily secure the muffler with something placed under them. This will allow you to devote full attention to determining the correct length for the Head Pipes. Muffler length should be limited to a maximum of 20" case length. Note that often moving the muffler rearward just a little can allow for more tailpipe rotation which can help with proper positioning and angle at the end of the tailpipe. Lowering the muffler can also help sometimes. When cutting Headpipes to length, always cut "long" as this places the muffler farther rearward. Remember, you can always shorten the Headpipe, but its hard to add length. If you are installing the 2-piece Tailpipe for the longer-tailend A-Body Vehicles, then you will need to trim off an appropriate amount from the end of the tailpipe. If you are installing the Straight Extension onto the tailpipe, then you can trim off the end of it instead. Both Walker Super Dynomax and Flowmaster mufflers work equally well. Offset in/offset exit mufflers are necessary for best fit

8. Mount Collector Reducers onto end of headers if you have not already done so.

9. With mufflers in place, mount the Headpipes onto the Collector Reducers and determine how much you will need to trim off the Head pipe. You may trim off the end of the Collector Reducer also.

Remember, measure and re-measure, as it's easier to trim a little more off than to add. If the Head Pipe does not reach far enough back, then you will need to do one of two things. Add an extension between the end of the Headpipe and the muffler (we have the extensions) or for a cleaner installation, we have the HL series Head Pipes that are 10" longer than the standard length. HL Head Pipes are rarely needed and then mostly on the longer wheel base vehicles such as the El Camino and Caballero. The GTO's have a tendency to come up short more so than other A-Body vehicles.

10. Fine-tune the fit. Once you have trimmed the Head Pipes for proper fit, then begin "fine tuning" the overall fit of the system. Do not tighten clamps until you have everything fitting. Consider suspension movement while fine-tuning.

11. Check for leaks upon completion. Normally good sealing occurs with clamp type installations. However, occasionally we run into a situation were proper sealing is difficult to obtain. If this is the case, first try tightening the clamps a little more. However, with a lot of tightening, it is possible for the pipe to start crimping or the U-Bolt to "break". OR, try relocating the clamp forward or backward from its present position and re-tightening. Another possibility is trying "muffler cement" which can be purchased from any muffler shop, or auto parts outlet, or us. If there is excessive clearance between the two pipes or muffler and pipe, then it may be necessary to cut one or more slots in the outer pipe to allow it to compress further for better sealing. Try to rotate clamps so the bolt part is not pointing downward for a cleaner looking installation.

12.

Now, its time to consider mounting the Balance Tube Kit. (This may be a project for a professional if you don’t have welding equipment handy or the welding skills or a buddy with such). Both kits are installed the same way. It is the only part of our system which needs to be welded and luckily this is done last after everything else is in place. Ideally, to determine the best mounting location, you will need to spray a line of paint on the side of the head pipes from the collector reducer back approximately 20". With the vehicle running, you can determine at what point the paint stops burning off. This is where you want to mount the Balance Tube. If for some reason there is an obstruction prohibiting this, then mount it as close as possible to that point. We have found that usually mounting 8 – 16" from the collector works fine.

13. Now that you have determined where to mount it, you need to determine the length. Remember to allow for the curvature of the Headpipes as you will want to have some curvature on each end of the Balance Tube. (With Kit B, first install the short piece of pipe into the longer piece and maybe hold together with the Band Clamp – now you know the overall length and determine everything just as if it were Kit A). Remember, better to cut too long than too short.

14.

Now cut the holes in the side of the Headpipes. They do not necessarily have to be as big a diameter as the size of the Balance Tube. Do not allow parts of Balance Tube to protrude into the Headpipe as this will impede flow and be counterproductive. IF hole is cut a little too big OR if Balance Tube is cut a little short, you can "Fill Weld" in the gaps to make fit. It will be a good idea to paint the welds with some Hi-Temp Paint as this will help protect it from rust.

** Muffler Warranties: Please remember to keep your invoice as this will help greatly with any problem one might have.  Generally, we have found that very rarely is there a problem with either the Flowmaster or Walker Mufflers. 

X X The above True Dual System is intended for Track or Off-road use only on Pollution Controlled Vehicles X X

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