Duraspark Conversion Fail

[Steve83]

844rd wrote

Not all 4-terminal relays are identical.  The 4th (small Right) terminal can be an "I" output, or a negative for the winding.  And there are other configurations, but those are the 2 most-common.  So before you condemn them as being "bad"NIB, test resistance from the S terminal to the other small one.  If it's still OC ("1" on your meter), then it's probably bad.  But if it's about the same as the good relays' windings, then they're just boxed wrong - they're the non-grounded type (for use in a wider variety of applications).

But regardless; the later style relay (parallel posts) is superior, and everyone should switch to it.

[LARIAT 85]

Why is the later style relay (with parallel posts) superior?

My EEC-IV truck originally had that one.  When I did my own DSII conversion, I switched to the earlier style relay because that is what all of the earlier vehicles with DSII used.

[Gary Lewis]

The later style solenoid probably isn't "superior" for a truck that doesn't need the extra connection, which is for the fuel pump control, as shown below.

More specifically, pages 102 & 105 are for the 460's with electric fuel pumps but DS-II.

[Steve83]

Yes, always superior.  These show why:





The 4th terminal can be had on either style of relay.

[Gary Lewis]

Steve - I don't think that was Rick's question, but I could easily be wrong.  I think he was asking if the "old style" solenoid with the "side terminals", as you called them, but with two small terminals was better than the one with one small terminal.  Anyway, that's the way I took it, although maybe Rick can comment.

Anyway, regardless of the original question, your answer is quite interesting.  I didn't know how the newer style solenoids looked on the inside, and that explains a lot.  Thanks, I appreciate the info.  

[Steve83]

Gary Lewis wrote

...two small terminals was better than the one with one small terminal.

They're different, so they can't be compared as "better".  It's like a 1056 bulb vs. a 1057; they have different uses, which is why they have different terminal counts.  In the case of the starter relays: any with 2 small terminals can be used in place of any with 1 (possibly requiring an extra small wire), but NOT necessarily vice-versa.

[LARIAT 85]

Gary, I was referring to the older relay with the big terminals on the side versus the later relay with the big terminals on the front.

Thanks for answering that, Steve.  After studying your diagrams, I just might switch to the newer style.

It seems you are using the later style part number (E9TZ-11450-B) for both the early style and the late style relay in your diagrams.  The part number I have for the earlier style is E7HZ-11450-A.

Was E9TZ-11450-B a superseded part number?  Because my 1985 model (with EEC-IV) originally had one that looked like that when my father got Lucille in the early 1990s, and it looked original.

E7HZ-11450-A is obviously a superseded number, so I wonder if they were somehow improved to be as good as the later style?

[Gary Lewis]

Ok, got it. And thanks to Steve we now know that the later relay/solenoid is better.

[Steve83]

LARIAT 85 wrote

It seems you are using the later style part number (E9TZ-11450-B) for both...

Good catch.  I don't remember why I did that (if it's superseded, or just my mistake), but I don't think I'll change it because I don't really want anyone getting the old-style relay.

LARIAT 85 wrote

...I wonder if they were somehow improved to be as good as the later style?

They're not & can't be, for the reasons explained in that caption.  My interpretation of those numbers is that they might have TRIED to improve the design in '87 (E7), but found that it wasn't significantly better, and came up with the new design in '89 (E9).