Distributor problem

[pineneedle]

Michael and friends, I have a prestolite electronic distributor on my 1978 304. I tried to buy a vacuum advance can today at the local parts houses, and they are telling me that it is no longer made. Where can I get one, or, is there a work around?

Pineneedle

 

[Michael Mayben]

michael and friends, I have a prestolite electronic distributor on my 1978 304. I tried to buy a vacuum advance can today at the local parts houses, and they are telling me that it is no longer made. Where can I get one, or, is there a work around?

Pineneedle

The workaround is...replace it with a functional one!

I know...smartazz answer! I've not found any other replacement for those, if they are not available through normal channels for the prestolite stuff on IH, they are also not available for other applications of similar distributors used by other oem/marine manufacturers.

I'll call our regional prestolite distributor tomorrow and see what they say regarding availability. They do have some parts available on the shelf.

We have used ones right now. We have cores being remanufactured right now. There May be some new ones on the shelf at ihon, call Jeff and inquire.

 

[pineneedle]

Michael,

I read your recent post about discovering that old school distributor shop. In your post you say that you are going to delco distributors. Maybe that is the route I should take. What exactly is involved, ie, how would I go about getting one, what specs should I look for, etc.? I have a '78 vintage 304, as I stated above. As usual, I am deeply appreciative of any assistance you can give me.

Pineneedle

 

[Michael Mayben]

I haven't heard back from our prestolite distributor warehouse distributor yet john.

Any of the oem sv distributors are basically "drop-in" replacements, though each and every individual IH part number has slight variations in the overall timing curve designed in. And any of 'em can be re-curved to virtually any setup by a reputable shop with experience in doing this. The delco unit was oem on the 266 and some 304 applications in the s800 and pickalls up through '68 or so.

The advantage to using a delco unit is that the mechanical advance unit is on top right under the rotor. And...many aftermarket parts kits are available for playing with that mechanical advance curve. Same for sourcing an easily-adjusted vacuum advance can!

And anyone with some patience and tech-ability can alter/dial-in the curve using a timing light with the dial-back feature (or sometimes called a timing advance tester), and a shop tachometer with high resolution. Pop the cap off, remove the rotor, and play with the springs!

Add in a pertronix conversion trigger system and a msd/mallory/crane/accel/whatever "6 series" capacitive discharge box and a low primary resistance/high turn ratio "matched" coil and ya gotta state-of-the art ignition system!

The msd "pro billet" distributor is pretty much the standard of the aftermarket distributor industry for engines for which msd manufactures an application. The upper portion of those distributors are all identical...that upper body "bolts" to the lower portion drive unit which is application-dependent. But at the present time, msd does not offer an ihc-app of that unit.

Those distributors use the oldskool delco upper portion/mechanical advance mechanism in combination with a msd-produced Ford duraspark-type magnetic trigger. And then that can be combined with a delco-type hei module in order to interface with an efi system. So those units are not all that
"special"...msd simply took design elements from oem systems that are very common and inexpensive and built a distributor around 'em.

As for the electronic distributors...the Holley gold box system, the prestolite electronic unit like you have, and the various pertronix conversion modules are all "hall effect" triggers. They will all trigger a "6 series" cd box, though using a box with either the prestolite or the gold box systems is a total waste and can be problematic going forward.

 

[Michael Mayben]

michael,

I read your recent post about discovering that old school distributor shop. In your post you say that you are going to delco distributors. Maybe that is the route I should take. What exactly is involved, ie, how would I go about getting one, what specs should I look for, etc.? I have a '78 vintage 304, as I stated above. As usual, I am deeply appreciative of any assistance you can give me.

Pineneedle

I guess I really didn't answer your question john!

Your engine is '78 vintage...but the cam specs and all are exactly the same as the very earliest motors! And yore choice of carb and all that we've already delt with is based on "old" stuff which is pre-emissions. So forget all the "specs" for the distributor in the '78 stuff which was all predicated for emissions.

If you look through all the distributor specs for the 304 over all the years of production, you will see that many different curves were incorporated.

Any distributor you choose would benefit from being set up per the specs for say 1968-era stuff since the motor is "stock". And then, using that baseline, you could play with seeing if you could improve performance once the rig is drivable.