Work is progressing nicely...
Work is progressing nicely on this '87 Grand National at Cotton's Performance Center in Agawam, Massachusetts. Originally slated to be a quick bolt-on street car, the owner has upped the ante and set his sights on the 10-second zone.
Before we move on to the fuel...
Before we move on to the fuel pump and framerail work, we wanted to show before and after shots of the rearend...
Jack and Brian Cotton of Cotton's Performance Center have put several days of hard work into converting Frank Vallelonga's near-stock '87 Grand National into a streetable 10-second hot rod. Our last two installments ("10-Second TR," Oct. and Nov. '05) covered upgrading the rear suspension and rearend to handle the expected horsepower. Now, with the majority of the GN's back half attended to, there are only a few more loose ends to tie up before the engine can start going together.
The original fuel pumps that GM installed in Turbo Buicks were the 98-pound weaklings of the fuel system set. They could barely handle the 12 pounds of boost that these cars pushed stock, and anyone who increased the boost had to start thinking about more fuel, quickly. Back in the day it was common to add a noisy external "pusher" pump when the stocker started failing, and many racers looking for 10s did the whole shebang: an external pump or two and new fuel lines.
Thankfully, Buick racers are nothing if not imaginative, and soon a design called a "double-pumper" emerged. This was a dual-pump, in-tank system that was quiet like the stocker, yet could supply enough fuel through the Buick's adequate fuel lines to feed a low-10-second turbo V-6. Since Frank's GN will be seeing street duty as well as shooting for 10s at the strip, it is the perfect fuel system for this build up.
Another important task that Cotton will be performing is the notching of this GN's framerails to allow for larger wheels and tires. While the idea of taking out some frame material to fit larger meats seems to be pretty straightforward, any modification to the frame can turn ugly if it's not cut correctly and properly reinforced. With the amount of torque these cars develop, it would be a shame to twist up a notched framerail. We watched Brian Cotton perform this process step by step; read on and see how it's done.
...The crew at Cotton's Performance...
...The crew at Cotton's Performance Center and the owner have put a lot of work into this rear, and what a difference it has made.
To remove the stock fuel pump,...
To remove the stock fuel pump, the factory tank must come down--this is much easier with only a little fuel in the tank. With a jack supporting the tank, the 15mm bolts on the gas tank straps come off, and the tank is lowered enough to reach the fuel lines.
There are .25-inch bolts on...
There are .25-inch bolts on the fuel line clamps that come off (pliers work here) before the tank can be completely lowered.
With those connections free,...
With those connections free, it is lowered down and the top is blown off to remove dirt that could get inside the tank.
With a punch and a hammer,...
With a punch and a hammer, Brian Cotton taps the retaining ring and rotates the stock fuel pump assembly to remove it.
The quietest method for providing...
The quietest method for providing juice to a 10-second V-6 is a double-pumper in-tank fuel pump setup, which Cotton's sells. This Quad Air XP Plus double-pumper is comprised of two Walbro 340 pumps that flow 255 L/hr. One runs all the time, and the other kicks on when the boost comes up. Since it's already pre-wired, it makes for a near-factory installation and none of the visual or audible changes of going to an external fuel system.
The installation is simple:...
The installation is simple: Brian simply makes the wiring connections, greases the new O-ring, and slips the new fuel system back into the tank.
Cotton lines up the tabs,...
Cotton lines up the tabs, and using the punch and hammer again, taps the ring back into position. The T for the Hobbs switch is connected to a vacuum source, and a new wire is routed to the engine bay for fuel pump power.
With the new fuel system ready...
With the new fuel system ready to roll, the fuel tank is replaced and secured. Although someone who is looking for a 9-second timeslip would need new fuel lines, the factory lines will work fine for 10-second ETs. (Jack claims to have run 9.70s with this fuel pump setup with his white T-Type, with minor mods to the fuel lines.)
Going solid 10s means having...
Going solid 10s means having more traction and a bigger footprint than the stock Buick wheelwells allow. In order to fit a 10-inch-wide tire back there, Cotton's Performance will be notching the framerails. Brian begins by cleaning up the framerails with a circular rotating steel brush tool in the areas that need to be notched.
The wheelwell is then hammered...
The wheelwell is then hammered close to the framerail; Brian uses caution here because the backswing can dent the lip of the fender. In the course of this project, some sections of the wheelwell metal will need to be replaced and the fenders will need to be rolled.
It only takes a matter of...
It only takes a matter of minutes to cut the outer edge of the frame with a plasma cutter. The front of the frame notch begins directly inboard to the framerail, from the lowest forward opening of the wheelwell. It proceeds back to the rear of the framerail, 2 inches in front of the body-to-frame bushing. He cut out the outside of the frame and removed it before cutting inboard approximately .5- to .75-inch of the top and bottom of the frame. Cotton's uses the top and bottom from the middle of the frame as a guide to narrow the 'rail. In other words, they don't remove .5-inch front to back as the frame is of different thicknesses. Whatever the depth is, it needs to continue front to back.