Can't tell much of a difference yet, but I really haven't hit the road with it, other than a test drive.
Next up is the internally regulated alternator.

BTW any tips on timing by ear?:D

hei makes a ton of difference in most cases. Idle is smoother, starting faster and more performance.

Half the time the balancer has slipped a bit so I don't put much weight in setting the timing by a light on these old trucks. Unless you built the engine and have re-established TDC. I'll use it as a reference point only... to get the timing close. Then its time to "power time" it.

Best bet is find a good stretch of road where you can drive 45-60mph for 1-2 miles at a time. @45 put the trans in final drive (manual) or 3rd (automatic) and apply about 1/4 pedal on the accelerator. Increase speed speed to 60mph, if you notice pinging, stop and turn the dist' clockwise 1/16 of an inch. Continue doing this until there is NO pinging what so ever! Once this is done, back the timing off just a hair bit more (1/32"), this will compensate for low octane fuel or loaded vehicle runs.

If you don't hear pinging initially, advance the timing by rotating the dist' CCW until pinging can be heard, then refer to the above for the final process.

This will ensure your timing is at its peak performance without doing damage to the engine. If at any point you hear pinging, do something about it RIGHT THEN! Don't let the engine ping for a prolonged amount of time or you'll be shopping for new pistons ;) lol.

Get that alternator on there asap. HEI loves more voltage! (did you run a new 12ga wire for the hei?) Also its nice to get rid of the dimming headlights at idle.

I ran 10 gauge wire to my HEI, just came off the IGN UNFUSED terminal on my fuse block.

:bluechevy Don't forget to open up the spark plug gap a little this make a word of difference

I recently replaced the plugs and gapped them for the HEI when I installed them. But thanks for reminding me.

:bluechevy Here is a little info that i found interesting thought I would share it. Jacobs Electronics, a manufacturer of aftermarket ignition systems, has performed extensive testing of assorted spark plugs. They have noticed an increase in horsepower, on some occasions, with weak ignitions using specialty plugs. However, Jacobs' testers measured no advantage to using specialty plugs with their Energy Team, Omni-Pak and especially their Ultra Team ignition systems, and in some cases noticed a slight loss when specialty plugs, at the same gap, were installed in the place of standard steel plugs. On the other hand, Jacobs has seen a gain with specialty plugs when their lowered arc-over voltage has allowed users to increase the plug gap above that possible with steel electrode plugs.

For example, Jacobs tested a 253-cubic-inch V6 engine, which was slightly modified; the factory called for a 45-thousandths (0.045") spark plug gap. With stock ignition, it produced 168 horsepower. Platinum plugs increased horsepower to 171. SplitFire plugs also brought horsepower to 171. Surface gap plugs increased horsepower to 172.5 - actually a little closer to 173. Jacobs then installed an Ultra Team and replaced the steel gapped spark plugs; horsepower increased to 180.5. Retaining the 0.045" gap, the testers installed the specialty plugs, and the horsepower fell to 178.5 for all three types. The reason for this power loss was because it required less arc-over voltage at the same gap; therefore, the peak spark power fell slightly.

Further experiments with the Ultra Team and different spark plug gaps produced some interesting numbers. With steel electrode plugs, the peak horsepower achieved was 186 at 0.063" gap. With SplitFire plugs, the peak horsepower achieved was 184, but it required a 0.067" gap, which caused some concern about the piston contacting the side electrode. The platinum plug achieved a peak horsepower off slightly under 185, with an optimum plug gap of 0.066".

So what can we conclude? While specialty plugs can mask the effect of an inadequate ignition, so can reducing the plug gap in many cases. One of the true tests of a good ignition is to install a specialty plug instead of a standard steel electrode plug; of the performance of the engine significantly increases at factory spark plug gap, then the ignition was either inadequate or operating in its marginal range.

Good read there. I find it funny to see all the "Specialty" plugs come and go but the same old regular plugs are the ones that prove themselves.

Now when you introduce fuel injection into the mix, this can allow you to go with the double platinum plug (ac delco) but don't try this on a carb'd engine. You'll be fouling plugs like mad.

I went to HEI a few years back on the 250 and it was a world of difference. HEI's for 6's are a little more scarce... but I found a guy on Ebay hawking Jeep HEIs who sold me a rebuilt unit for $75. Quick swap and well worth it.

As for plugs, I prefer Autolite and AC in that order. Anyone else?

Got AC in my truck.

Ill never run points again.

Originally posted by 68 Suburban
Ill never run points again.

I still have them in my 52, but I couldn't see shelling out the money for a Pertronix for no more than I drive it. Eventually she will get pointless ignition, either with a 261 or a 292 attached.

I had a 74 with a 250 that had the small plugs. I tried all the major brands of plugs, but the ceramic would break down between 5,000 to 8,000 miles. One day I was in Monkey Wards, they had an ignition module on closeout for $10. After I installed it, plug life was over 10,000 miles. Aren't modern electronics great!
:bandito: