May  2002

This page is all about rodding the straight-8 cylinder head.  Kustoms are all about looks, but not this one.

Allright. I just couldn't leave it alone. My goals for my Buick's performance are: It shall make as much rear wheel HP as the it made brake horsepower in OE trim (144 HP). Let's suppose the power loss of drivetrain is 30%, that equals 205 brake HP It will pass 1/4 mile in less than 20 seconds, and have a trap speed of over 60 mph Top speed will surpass that 100 mph of a pre-war Buick Century (don't care if it takes a downhill) Highway Mileage shall not be worse than 16 mpg (about 15 L/100 km) Now for the mods. When I first disassembled the head, it was crystal clear why this huge engine doesn't make more power. Yes, the 2-barrel carb, lousy intake and exhaust manifolds all contribute, but this head simply cannot breathe. So I did what I could to improve it. The horn-shaped intake valve has a cup of 5 cc on the combustion chamber side. So they gave way for Big Block Chevy exhaust valves. The Manley Race Flo stainless valves are a direct swap, less retainers and locks. The stem is only some 1 mm taller - no problem. It's a necked down swirl polished valve.  It flows well and is slightly larger than stock at 1.88". As a side benefit, the combustion chamber is now 5 cc smaller. As for the exhaust valve, I just gave them a narrow 45 degree cut and a 30 degree back cut.  I didn't touch the ports other than a bowl job, which was not a small task at all. I had to grind lots of metal to get the bowls measure the optimum 0.9 x valve diameter. The seats are not cut in 3 angles. Instead, there's the 45 degree seat and a smooth constant 12 mm radius to the port. Yummy!  I also shortened and contoured the guides.

Then I coated both the chambers and the valve heads with Tech Line CBC2 ceramic thermal barrier coating. Nice. Finally the deck surface was milled down a full 1 mm, which again raises compression ratio. According to my calculation, we are at 7.6:1 now (instead of the original 6.6:1) including the filling of the piston dish. That equals about 3-5% more power but more importantly some 13% better mileage. The coating should net a similar effect.

Yes, the rockers were glass bead blasted. All in all, it was a horrendous job cleaning the valvetrain of all the varnish and smudge. Here you see the intakes fitted with original springs and retainers, but with aftermarket 10 degree locks. However it didn't work out as the valve tip sits too deep in the retainer, and the rocker almost touches the retainer. The best bet would be to use stock BBC valve springs, retainers and locks. But I wanted to save money so I took a set of used SBC springs and retainers, and machined the retainers for the larger 3/8" locks. I also had to fabricate 1/4" thick shims since the SBC springs are much shorter.  If this is not hot rodding in it's truest sense, what is?