Back to the build...
The ignition system I have is based upon an MSD 7AL buzz box and a simple matching MSD canister coil. But to trigger it, I did something different. The new kids who look after tech at MSD are aghast...(seriously)...like "that'll never work"...even though the instruction sheet for the 7AL2 clearly shows how to wire it for a point trigger distributor....L-O-L. I use a point trigger Delco to tell the MSD when to fire. There are reasons for this: The old Delco point distributors were (and are) extremely stable when properly setup. When properly setup, they're stable at 7,000 RPM. They are also very reliable. When used to trigger a buzz box, there is no need for a condenser. All the point set does (and you can only use a single point distributor) is to act as a switch. With this setup, points last almost forever. And the big deal is, I don't have to rely upon an often shaky electronic trigger mechanism (fact: way back when, when I owned a couple of speed shops, we actually warrantied more Mallory Unilite electronic distributors than we sold). Here's the overall setup out of the car:
The basic Delco I used was a super low mileage job from a 307 and as a result, the bushings were perfect. First things first, I set the end clearance. They're regularly way off GM spec and I have to shim them:
Upstairs, I limit the amount of mechanical advance:
I use one set of ACCEL performance (not race) points. Note no condenser:
I usually use Moroso weights and springs. For this application (with an automatic) I want the curve to come in quickly, so I use the lightest springs:
Some might scoff, but I still like to use a vacuum advance setup on a street car. It just makes sense, especially when cruising at a constant speed. This is an old Crane setup I used, and it's adjustable. I set it for the least amount of vacuum advance.
With a steel cam (roller) and a steel drive gear on the cam, you either need a bronze distributor gear or a melonized gear. I prefer the melonized gear. FYI, Chevy uses them on their roller cam crate engines:
Upstairs, I prefer the old ACCEL caps and rotors. They're heavier and more robust than the new MSD pieces:
This is the finished distributor (less the melonized gear...which was installed later):
My intake manifold choice posed a real problem. The intent was to use a Weiand Strip Warrior single plane. But it clearly wouldn't allow the hood to close. I wasn't about to use any sort of hood scoop and I wasn't about to sacrifice filter area. Here's the Weiand in the car:
I needed something shorter, but there are some really issues: Stock big block Chevy intakes have a bolt hole over each siamese intake runner. Most aftermarket heads like the Brodix BB3's I use don't have the corresponding hole. Here's a look at an intake for a stock Chevy head layout:
If you place an intake gasket for a Brodix BB3 Xtra head over the manifold, this is the result...Incredible vacuum leak...L-O-L:
Because of all of this, the options aren't that great: Weld the offending bolt holes in an intake (that will fit) or find an intake that does work. In truth, there is only one out there, and it's about to be discontinued, simply because it costs lot of $$$. It's a Brodix dual plane intake. Here it is, side by side with the Weiand:
I suspect there's a pretty good power loss with the Brodix although Scott Shaffiroff's testing has proven it's not really that bad. On the car, it's easy to see it can clear the flat hood:
Here's the intake on the 565-cid big block. I sure can't complain about the throttle response...It's over the top. In fact, the big block rotates the tach like a hot small block.
That's it for this episode...Stay tuned for more...