Power Wagon- Installing a Weiand Supercharger
High horsepower has always been the hallmark of a hot rod. The horsepower wars are alive and well at the factory level and increasingly the OEMs are using superchargers to get the numbers. Forced induction has been a standby for hot rodders for over half a century. Traditionally you will see a huge blower protruding out of an equally huge hole cut from the hood and topped with towering carburetors. The factory keeps their installations lower key. Most of them fit under the hood or at least under a scoop of some sort. In our case we wanted to add some more power, but also drivability and have it all fit under the stock hood of our ’75 Chevelle station wagon. While hacking a hole in the hood or bolting on a cowl induction hood has its place, it would certainly take away some of the sleeper-factor. So we came up with an ultra-low profile combination of parts for a killer induction system.
Our starting point is a standard 350 small-block Chevy with a bottom-end torque cam, Brodix IK180 aluminum cylinder heads, Hooker headers, an Edlebrock Performer intake, Q-jet carb and HEI. Compression was about 9 to 1 so; overall, it seemed like a pretty good package but in a relatively heavy car. To be honest it was not performing to our expectations, thus the search for some additional power. It was also giving us tuning fits. The Q-jet was recently rebuilt but would not respond to tuning attempts, and had a bad fuel pump as well. So with our plan for new parts and more horsepower we tore into it and didn’t look back. We knew straight away that we needed the lowest huffer we could find, and because this was for a 350 Chevy, we could use a Weiand 144. The 144 installs .75” lower than the 142 due to a different intake manifold; therefore, it was our ticket to success. For our setup there just wasn’t any room to add another accessory to the front of the engine.
The Weiand roots type blowers have been around for decades and are proven technology. You haven’t heard much about them in the last 10 years or so because of the popularity of centrifugal designs but each has their place for solving different packaging limitations. Not only is the technology proven on this blower but the installation package has had all the bugs worked out years ago so the installation is very straight forward. Just about everything bolts to the top of the engine. It is about as simple as a manifold swap but definitely cooler looking.
The fuel mixer was our next challenge and we were rapidly running out of height for this combination. A typical Holley or Q-jet carb was going to be too tall if we expected to run an air cleaner. So we selected the Holley Avenger EFI system because the throttle body had the lowest overall height and the computer could handle boost when tuning the engine. We wound up with a combination that was just 1” taller than the Q-jet/performer manifold currently on the engine. Because we were running a 4” tall air filter we could step down to a 3” for the time being until we could add the cowl induction hood at a later date.
The blower coupled with the EFI will give us the power boost we want as well as the drivability we are seeking. Today, it is expected that a street machine be as well mannered, or at least not as temperamental, as it is fast. The days of boost referenced carburetors or finding the guru that knows all the tweaks have passed. You can now buy your own guru and it comes in a little black box. Technology is a great thing and it has done wonders for performance cars. This project combines older technology (roots blower, small block Chevy) and newer technology (EFI) to achieve something that is drivable on a daily basis.
1. Here is your basic small block. It’s not fancy and certainly in need of a few upgrades.
2. We performed a baseline dyno run and the numbers confirmed what we expected. It also revealed that the HEI was really having problems over 4000 rpm. It was later discovered that the coil was bad despite the fact that the distributor and coil were brand new.
3. Use a sharpie to mark all the plug wires before you remove them from the cap. It easily rubs off after you are finished so it is a nice trick to use on any car.
4. This is the nearly 30 year old induction system. It was put on the car in the ’80s and has served well on two different engines running about 150,000 miles.
5. The sharpie is handy for marking where the distributor is set. This will make it a snap to re-install and get the timing to where it was originally.
6. The big items for this project are the blower and EFI. Holley includes a complete wiring harness that makes installation a breeze. A slick HP electric in-line fuel pump also makes it simple to install EFI on a carburetor plumbed car. We decided to use a blower cam to maximize the potential. Comp Cams makes a version of their 268 grind that is specifically for blowers.
7. Changing the cam makes for a more complicated installation due to the engine tear down required (remove radiator, accessories, dropping the pan, etc.), but it’s also important to have all the parts properly matched. A new timing chain is also a good idea. Be sure to goop up the flat tappet cam with a lot of break-in lube. You don’t want to round the lobes or chew up the lifters.
8. The manifold is well outfitted with ports for sensors and we took advantage of them. The top left is the coolant temp sensor for the EFI and the left lower is for the stock gauge. We will fill the far left with the heater valve.
9. Recommended intake manifold gaskets are Fel-Pro 1256.
10. The gaskets fit the Brodix heads beautifully. Use a little shot of gasket glue to hold them in place as you set the manifold down. Run a bead of RTV at both ends rather than using the supplied seals.
11. Installing the manifold is straight forward. Follow the standard torque sequence starting at 15 ft. lbs. and finishing at 30.
12. Re-install the distributor and align the mark previously made on the valve cover. There was also a mark made on the distributor body indicating the location of the rotor.
13. The thermostat and housing are next. Weiand supplies the nice chrome housing that incorporates a rubber o-ring seal. There’s no need to ever buy a housing gasket again.
14. Working on buttoning up the front for the engine we used the supplied fuel pump block off plate.
15. Now we are getting somewhere! There are only four bolts securing the blower to the manifold. The gasket needs to be coated with a light dusting of baby powder to keep it from sticking. The bolts are tightened in a crossing pattern working evenly up to 10-12 ft. lbs.
16. With the bolts torqued it is critical to check that the rotors spin freely and that the case to rotor clearance is correct. Using a .012” feeler gauge, check the clearance along the length of each rotor.
17. The supplied 10 rib crank pulley and spacer install in this sequence. The correct length bolts are also included.
18. Once installed, you must check the pulley alignment by setting the belt in place.
19. The throttle body installs just like a standard carb. We used Lokar cables for the throttle and transmission TV. They make beautifully crafted products that are very easy to use. They are simple to trim to a custom length.
Sources:
Comp Cams
Holley
Hooker Headers
https://www.holley.com/products/exhaust/
Weiand
https://www.holley.com/products/superchargers/
I know this is a old article but, what type of torque and power numbers did you see after the blower and efi set up?
The engine was not dyno’d afterwards, and the oil pump went out about a month later, requiring a crate motor swap. The wagon was an absolute tire-roaster afterwards though.