To some, the intricacies of setting the ignition timing on an engine or changing a distributor may as well be black magic, while to others it's a procedure they know by heart, and as we took the opportunity to replace the cheapo distributor and coil in my '46 roadster pickup with Pertronix Flamethrower versions before I drove it to Bonneville, it offered the chance to delve into a subject that might be of interest, if the number of times I've seen people confused by timing markers and the subsequent inability to set their timing is anything to go by.
The following is specific to the small-block Chevy but is more common than you'd think, given the number of late engines stuffed into small engine compartments on the average hot rod. See, oftentimes to gain those precious few extra inches of room, the long water pump on 1969 and newer small-blocks is swapped for the earlier, shorter version. Not a problem you may think, but this means the new pump is now hard up against the timing cover, and the timing tab is now impossible to see, or may even have to be removed for clearance. Also, if an aftermarket cover is used it'll more often than not have no marker on it.
The answer is generally purchasing a bolt-on timing tab from a supplier such as GM, Mr. Gasket, Speedway Motors, or Summit Racing. Sounds simple huh? Well, yes, two bolts and it's attached to the timing cover, but it's not in the right place to correspond with the timing mark on the harmonic balancer, and you'll never set the timing correctly unless the mark is moved to correspond with the new tab. Forgive me if this isn't news to you, but it happens time and time again and must be the number one problem when trying to set the timing on a new engine.
With that tip out of the way, we'll move on to installing the new distributor, now that piston number one is guaranteed to be at TDC. Again, it's probably not rocket science to most, but worth repeating. The Pertronix Plug 'n' Play billet distributor has a factory set performance curve but is supplied with additional springs to customize the advance curve for specific engine requirements. We used it as it came out the box. It can be used with a multi-spark CD ignition box, the electronics acting as a trigger, but as my truck is hardly a performance vehicle, we opted to combine the Flamethrower distributor with one of Pertronix's 0.6-ohm 45,000-volt Flamethrower II low resistance coils, which doesn't require a ballast resistor.
The Ignitor II module in the distributor is similar to the Ignitor that has been available for around 30 years as a replacement for points in regular distributors, and senses the current levels in the coil, adjusting the dwell period for the best possible spark over the RPM range. I can report the engine ran much more smoothly with the Pertronix distributor compared to my old stock distributor and performed faultlessly for the 2,200+ mile trip to Utah and back without missing a beat, unlike some of the other components on the truck, but that's another story!
Here's the stock timing tab...
Here's the stock timing tab on an early 307ci motor, attached to the timing cover. The groove in the balancer lines up with the zero degree mark on the tab when number one piston is at top dead center (TDC).
Though it's not bolted in...
Though it's not bolted in place you can see the groove will also line up with this aftermarket tab.
The red cover is an original...
The red cover is an original 327 cover and has a tab attached, but the aftermarket chrome version does not, necessitating the new tab.
Tabs are available for 7-...
Tabs are available for 7- and 8-inch harmonic balancers. As shown here.
Here's a post-'69 350 from...
Here's a post-'69 350 from a Caprice, and again the stock timing tab (ARROW) works great but a swap to a short water pump necessitates using that aftermarket tab, and here's the problem. The timing groove is way off. The solution? Set number one to TDC using the original tab, then mark another line on the balancer to correspond with zero degrees on the new tab, and you'll have no problems setting the timing. It seems obvious but is a common mistake.
The engine in my '46 is a...
The engine in my '46 is a long water pump motor with the stock pump, so the above didn't apply, and although it was a freshly rebuilt motor, it had been fitted with a cheap points type distributor and unknown quality coil to enable me to fire it up and move the car around. Given the long road trip I planned for the car's debut, I played it safe and installed Pertronix's coil, wires and billet distributor. The Flamethrower II coil (which does not require a ballast resistor) was installed on the firewall. The old points and condenser distributor was pulled and put on the "probably-never-get-used-again-but-I'll-keep-it-in-case shelf." I can put those super long plug wires in the same place too.
Here's a tip from my pal Kiwi...
Here's a tip from my pal Kiwi Steve. Toss that nasty chrome blister pack distributor hold-down clamp in the trash and install a substantially beefier GM version (shown on the right) to prevent the distributor from moving. The inferior clamps bend and refuse to stay tight while the GM versions are made from sprung steel.
Don't forget to install the...
Don't forget to install the gasket before dropping in the distributor. The Pertronix billet distributor really is a Plug 'n' Play design, offering quick and easy installation and a two wire hook-up.
With number one cylinder set...
With number one cylinder set at TDC on the compression stroke, the distributor should be positioned with the rotor at about this angle if you have a non-HEI distributor. The most important thing to get right is to get the number one plug wire on the corresponding terminal on the cap where the rotor is pointed.
A cross shaft inside the bottom...
A cross shaft inside the bottom of the distributor shaft locates in the oil pump (the old distributor is shown here) and if it won't drop straight into place, the distributor can be held in the correct position as shown to the left. A couple of clicks of the ignition key to turn the engine over will usually see the distributor drop firmly into place. Once it drops, rotate the engine back around to TDC on number one's compression stroke and check the rotor.
The clamp should be tightened...
The clamp should be tightened with this special wrench, but most will use a regular box-end wrench for the job. Don't tighten it all the way yet, as the timing still has to be set. Note the old plug wires are still connected to the old cap, making it easier to change them over one by one.
The 8mm Flamethrower plug...
The 8mm Flamethrower plug wires are supplied with two sets of end caps, depending on whether your distributor has a male or female cap. The spark plug ends are fitted to the wires from the factory.
Installation is easy. With...
Installation is easy. With the wires attached to the spark plugs, they are run through whatever wire looms or clamps you have, up to the distributor. Once the length of each new wire is determined, they can be trimmed and the new caps installed. This is done by first sliding the rubber boot onto the wire (a little silicone lubricant will help), then stripping back 1/2 inch of insulation to expose the conductor core. This is folded back along the wire as shown, and a spark plug wire crimp tool used to crimp the terminal in place. The boot can then be pulled back over the terminal. Once all the leads are installed, you can set the timing as required for your engine, and you're back on the road.