Distributor Mainshaft

[John M.]

Is a 427-400 distibutor mainshaft a standard (all exc. spec. high performance)or special high performance. It's a non TI distributor. The catalogues list just these two (and the FI type).
Thanks for any help.

[Patrick H.]

Re: Distributor Mainshaft

In reality, it makes little difference. Why? You're gong to have to have the distributor recurved no matter which one you buy. Trust me on this one. I've heard that there is "some" difference and I've heard that there is "virtually no" difference.

Call High Tech Innovations in FL. They make them for everyone anyway, and I'm sure they can tell you more.

Patrick

[Joe C.]

Re: Distributor Mainshaft

John:

I believe yours should be standard type. All engines with mechanical lifters were classified as SHP. The difference in the mainshaft will be in the cam for the centrifugal advance weights, which will alter the cent adv profile. The point is moot unless you have the correct combination of advance cam/advance springs/advance weights. Many of the parts made today are somewhat different from the originals, and the best way to verify is to check the profile against the original distributor spec sheet.

Joe

[Joe C.]

PS

I can tell you that eyeballing the different shafts reveals SLIGHT differences in the adv cam. As Patrick says, having the distributor "recurved" might float your boat, but really shouldnt be necessary unless you are having a problem, or racing your car.

Joe

[Patrick H.]

Re: PS

I bet he will ned it recurved.

Why? If you ask Joe L, there were of variety of original cams on the top of the shafts. Each engine had its own. As a result, you're in for pure guesswork if you just swap springs and weights, and call it good.

The distributors in my 71 and 72 are original. You wouldn't believe how far off specs one of them was with the original weights/springs still in place. I have a 3rd distributor I built for the 71 that had to be completely redone as well. When I swapped shafts, as after 30+ years, the springs had worn out, and I can verify personally that the mainshaft's cam was very different between the two distributors. It was much more than slight.

Trust me, spend the $25 or so and have it recurved. It made all the difference in the 71.

Patrick

[Joe C.]

Re: PS

Patrick:

There is no need to have the distributor "recurved" when you can verify for yourself:

1. The RPM at which the centrifugal advance begins.
2. The RPM at which the centrifugal advance is maximum.
3. The total centrifugal advance, in degrees.

The DESIGN values for these 3 parameters are listed in the original spec sheet for your engine. When you pay the technician to "recurve" your distributor, these are the 3 criteria that will be manipulated.
The only reason that I would pay someone to "recurve" my distributor, is if I had reason to alter the advance profile from design spec.--such as racing. If this were the case, then I would have to trust his expertise, and I would be paying for his SPECIFICATIONS, and not the actual "recurving", which can be done by manipulating 3 entities in the distributor.

Joe

[Patrick H.]

Re: PS

Joe,

Yes, but when the original distributor springs are so weak that the advance is starting at 600 rpm or earlier, you really can't start to verify much. In addition, what are you going to start to manipulate yourself at that point? Stretch a spring to loosen it up? Cut off a coil to stiffen it and make it come in later? And spend how many hours doing that on the car?????

In addition, my technician has a wide variety of new and used springs at his disposal. Using those he can accurately reproduce either my original curve or whatever curve I want. At $25, I'm paying for access to his wide variety of springs, none of which seem to match the generic ones you buy anywhere else, and the fact that he can do it in far less time than it takes me. Yes, I tried and tried and tried to check out one of my distributors on the car myself. I then tried several springs, and had disappointing results each time. I now have written reports of my current distributors in their current configuration, and can compare them to their original specs. In addition, for a small additional price, I can get a set of springs to swapin that will alter the curve if I so wish.

The best $25 I ever spent on my 71 was to have the distributor curved as I wish, and then the $15 for a distributor can matched to my engine's vacuum characteristics. The car has been transformed from what it was a year ago with its stock, stretched and loose springs.

Another distributor of mine gets reassembled next week. There's no way I'm spending hours playing with the curve and getting frustrated. I'll get it back instead from my technician with a printout and ready to drop in. No muss, no fuss, and perfect.

Just my thoughts. But they come after several years of trying to do it myself.

Patrick