Anyone have an original 69 L/78 with THM400 ?

[William]

Worthy of note is that not all SHP bb/TH400s used the solenoid set up. The best known example is the L89 car tested by Popular Hot Rodding April '69. There is a clear engine photo showing no solenoid. Super Stock also tested a automatic ZL1 [#5?] that did not have it. The solenoid seems to be a late production addition, do not know for sure.

[nuch_ss396]

[ QUOTE ]
Worthy of note is that not all SHP bb/TH400s used the solenoid set up. The best known example is the L89 car tested by Popular Hot Rodding April '69. There is a clear engine photo showing no solenoid. Super Stock also tested a automatic ZL1 [#5?] that did not have it. The solenoid seems to be a late production addition, do not know for sure.

[/ QUOTE ]

In your examples, what would constitute late production?

Now that you mention it, I do recall having a discussion
about this some time ago and what I recall ( now ) is that
not all L/78's w/THM400 got this solenoid. It was never
couched in the context of early vs. late production though.

Can anyone else verify this or comment further? There must
be some L/78 owners out there with survivor-like cars that
can shed some light. Would Chevelle vs. Camaro vs. Nova all
share this early vs. late production difference?

Steve

[Hotrodpaul]

I have a 70 Z28 TH400 with the Holley and Idle Solenoid. I can post some pics if needed.

Paul

[Hotrodpaul]

Here you go:



Paul

[William]

The PHR L89 car still exists; L507xxx VIN.

When we were doing the ZL1 the solenoid question came up. The photos of #5 don't show one but by the time the car was tested it had been modified somewhat, had headers. There was a L72/TH400 COPO sold in Canada, an original owner car into the '90s that had the solenoid, N661xxx VIN.

That is what I know. We did not put one on the ZL1.

[nuch_ss396]

[ QUOTE ]
Here you go:



Paul,

Can you show me a top-down image of the bracket & solenoid
so I can see wxactly how it mounts to the carb.? I know
this is a 1970 small block production setup, but I just
want to know a little more about how it is assembled.

BTW, is the Holley base plate drilled & tapped to accept the
solenoid bracket screws?

Thanks,
Steve

Paul

[/ QUOTE ]

[Hotrodpaul]

Top Pic:



Paul

[nuch_ss396]

Thanks Paul!

Steve

[nuch_ss396]

Follow-up on this topic:

Through my investigation thus far, I have arrived at the
following. If anything is incorrect, please clarify for
me.

1) It appears that the 4346 Holley did not incorporate the
use of a special throttle arm for THM400 applications.
No one can attest to the existence of another part number
for a 4346 throttle arm. So, manual and automatic cars
used the same carb. - correct?

2) It appears that the idle stop solenoid used the bracket
that mounted to the intake manifold with two studs.
Every L/78 & COPO example I can find uses that same
setup. I have looked at Camaro's, Chevelles, and Nova's.
Has any member seen an original setup the differs?

3) The first reply to my initial question includes an
image of a COPO Chevelle restoration. The 4346 throttle
arm clearly shows the existance of a ball stud. My 4346
for my Camaro does not have this stud. So, how can they
both be 4346's? Is there a separate part number for the
Chevelle throttle arm vs. the Camaro & Nova throttle arm?


Questions yet to be resolved:

1) If the ZL-1 used the same idle stop solenoid and kickdown
setup as was used on L/78 & COPO Camaro's, was there any
difference in relation to the 4296 Holley that was
used with the ZL-1? I'm betting that the 4296 had a
very different throttle arm. Does anyone here have a
good, clear image of a ZL-1 w/THM400 carb/solenoid
assembly?

2) Two ZL-1 Corvettes were also produced. I believe they
also used 4296 Holleys, as did the L-88's - correct?
Didn't the Vettes use throttle cables and thus a ball
stud on the carbs throttle arm? As we know, the 69
Camaro used a throttle rod, so no ball stud was needed.
Was the ball stud installed on all 4296 carbs anyway?
If not, wouldn't that indicate a separate part number
for Vette vs. Camaro? How does this fit in with the
4346 throttle arm observation?

3) Most ZL-1's were mid-year productions - right? I have
been told that a few early ZL-1 Camaros were produced in
January. It was also started to me that 4296 Holley's
have not been found with dates that would support a
January build. Can anyone dispute this? Lastly, did
all ZL-1's use the 4296 Holley? Were the early ZL-1's
possibly all manual transmission cars anyway?

This just keeps going, and going, and.....

Steve

[William]

The '69 4346 carb is the same for manual/auto applications. '70 could be different; there are differences between manual/auto carbs for the Z28.

The 1969 Camaro assembly manual shows the bracket/solenoid setup for L78 on page A10 of the M40 section.

Most ZL1s were built with 4346 carbs, possibly because the ducted hood air cleaner vent tube interferes with the rear pump on the 4296. The only known photo of an automatic ZL1 Camaro shows no solenoid.

The first two ZL1 Camaros were automatic, delivered Dec 31, 1968. The remainder of Gibbs 50 were built and delivered during March 1969. 22 0f the 69 were automatic.

We swapped out a 4346 for a 4296 on an automatic ZL1 and no modifications were required. It is a direct bolt-on.