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OK, I pick up on the 400 engine that was all stock parts and ran 12.65 at either 108 or 109, I don't remember for sure. Now I'm tired of the car being a sleeper and I install a large cam. One that should have been way too big for what my 400 would want. I take it to the track and it runs 12.59 at 110. Since my car is no longer stock, it's time for headers. My good Pontiac friend had a spare set so I bought them from him. They were 1 3/4" tubes, truly equal length and clocked. Clocked means the exhaust at the collectors is assembled to follow the firing order. If you looked into the collector from the rear, the exhaust pulses would be going clockwise or counter clockwise. The "normal way they criss-cross, and the reason for that is easier routing of the tubes. This results in a circular motion in the collector which helps scavenge the exhaust. They have one tube over the frame on each side because of the routing required to make them "clocked". The brand is Headers By "Ed". They got so expensive I think he quit selling complete headers, and went to kits.
So I had to cut part of my fender well out by the clutch bell crank for the tube over frame. The tube bolts in separately, after the other three are in place. Although these headers work well, they were optimized for drag racing. The tubes were thin and a couple of bolts were difficult. One is almost impossible. I've spent as much as 6 hours on one of the bolts. It's the fourth bolt back at the back of the #5 and #6 cylinders. The tube wraps right around the bolt. The best way to get them on is to slot the flange, install the difficult bolt, and pull the headers over the bolt. It's still difficult, but threading the bolt with the header in is impossible.
OK, the punch line. The car ran 12.20 at 114. It's clear the RA manifolds became a restriction. Either because the cam was too big, or because they didn't like a 110 degree LSA. I drove the car this way for several years. It did sound pretty nasty. In 1978 I started building a 428. It took me three years, but the 400 was still running great. During those three years I decided I would put a nitrous system on the car. Remember, I'm street racing it, and using it for transportation. I'll pick up here next time.
So I had to cut part of my fender well out by the clutch bell crank for the tube over frame. The tube bolts in separately, after the other three are in place. Although these headers work well, they were optimized for drag racing. The tubes were thin and a couple of bolts were difficult. One is almost impossible. I've spent as much as 6 hours on one of the bolts. It's the fourth bolt back at the back of the #5 and #6 cylinders. The tube wraps right around the bolt. The best way to get them on is to slot the flange, install the difficult bolt, and pull the headers over the bolt. It's still difficult, but threading the bolt with the header in is impossible.
OK, the punch line. The car ran 12.20 at 114. It's clear the RA manifolds became a restriction. Either because the cam was too big, or because they didn't like a 110 degree LSA. I drove the car this way for several years. It did sound pretty nasty. In 1978 I started building a 428. It took me three years, but the 400 was still running great. During those three years I decided I would put a nitrous system on the car. Remember, I'm street racing it, and using it for transportation. I'll pick up here next time.
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