This comparison shows just how large the runners actually are next to a GM tuned port. The "inside" diameter of our runners is 1.75" . Don't be fooled by others using "outside" diameter dimensions. This is one of the BEST flowing systems available on the market today. 

It is the customer's responsibility to order the correct style base manifold for their project. We can assist with this identification process if you are not sure what style head you have. 

This is a picture of a typical rail mounting on the FIRST® base. AS you can see, the 3/8" NPT inlet from the fuel tank or the 3/8" NTP outlet to the fuel pressure regulator can be on either rail and the crossover tube can be mounted front or rear which would put the inlet and outlet facing forward if this suits your application better. Sometimes a 90 degree fitting may need to be used to clear the ditributor.

​Here is a picture of a cold air intake on the 78 Blazer. Feel free to contact us about purchasing cold air intake components.

Here is a typical fuel pump installation with pre-filter and filter installed.

This tool is a must have for installing the lower runner bolts. It makes life a lot easier! It is a 3/16" long wobble allen socket. Also remember it is much easier with the valve covers removed.

          Figure 1             Figure 2                   Figure 3                                

One common problem on the older units is that people have been known to remove the diversion plate  (figure 1) for reasons unknown. When this is done, it opens a large vacuum leak at the base of the throttle body (figure 2) which will cause extreme tuning and running problems. The fix is (figure 3)  re install the diversion plate. If lost, contact us and we will sell replacements. This plate is not necessary for the newer design,  assembly of throttle body with diversion plate in place to plenum (figure 5).

                           Figure 7

If you use a large cap HEI distributor, it will be a very snug fit. To help with timing adjustments, just remove some of the casting (figure 4). This will give you more adjustment.

Figure 4

These are pages from a 91 Popular Hot Rodding magazine putting the FIRST® up against other manifolds incl. TPI's Mini Ram and ASM manifold. This test comparison was to see which intakes could achieve higher torque numbers . This is not a horsepower comparison. This engine was designed to produce torque and was not built to achieve high horsepower numbers.  Remember when reading these articles, that the electronics that are being used were just developed at that time and there are far more superior electronics that will allow these manifolds to produce a lot larger numbers now. These articles are just to help give you an idea of some of the  potential this manifold has. This manifold has been able to support in excess of 650 hp on numerous applications. So along with he great torque numbers that this manifold can generate,  it has the  ability to move large volumes of air to generate high horse power numbers on specific applications. If you use a large cap HEI distributor, it will be a very snug fit. To help with timing adjustments, just remove some of the casting (figure 4). This will give you more adjustment.
Here are some measurements that you might find helpful when determining clearance issues for your vehicle.
Here are common sensors used with the First® TPI with corresponding Standard parts numbers.

IAC AC1T
TPS TH37T
MAP AS5T
COOLANT TX3T
MAT AX1T 
​02 sensor single wire
Heated 02 sensor
5 wire​ 02 sensor



NOTE: When using OBD 1 electronics In some cases the (IAC) idle valve may need to be set to the idle plate position to obtain proper idle correction. See procedure below. This procedure is done with the idle plate at idle position. It is also important to know that if the idle screw is adjusted you must reset the TPS after idle screw adjustment is made.



1. Turn ignition on

2. Jump A&B on ALDL

3. Wait 1 minute until IAC seats

4. Unplug IAC

5. Turn off key

6. Unplug jumper

7. Start up & set idle

8. Plug in IAC

9. Turn off ignition wait 15 seconds



      IAC #AC1T                   MAP # AS5T                     MAT#AX1T


To place an order please email:

Ken@Firstperfcenter.com

Our units also have the option of mounting the throttle body on the side. This can come in handy in tight quarters. When using this option, you will need to use a remote IAC valve for fuel rail clearance.

TPS  #TH37T                  CTS  #TX3T                    O2 sensor

Here is the proper way to mount the return spring bracket.

     Common sensors and Standard brand parts numbers.