Did the 1968, 427,390 hp have a solid steel line along the vac advance route?
I have an Aim and they show the 68 SB only.
I know it had a black 1/8" vac hose with a white skunk stripe.
I know it runs to the front of the carb on the drivers side.(Manifold Vac)
I'm just not sure if it left Detroit with a hard line or all rubber?
Thanks Again in advance
Marshal

 

Check the optional big block section for a note to the effect the vacuum line "installs same as base."

A second clue could be the page showing the line. If it has "19000" in the lower corner, that means all cars.

 

Hi Marshall,
The 390 picture I have is of a 69.
It shows a rather long vavuum advance pipe. It has about 6"-8" of hose on the distributor end, and about 1"-2" on the carb end.
Try Dr. Rebuild.
Regards,
Alan

PS: The bb engines are in the back of the AIM with the other options.

 

Mike/Alan,
Thanks for the responses.
I'll check in the back of the AIM and also for a 19000 notation.
As usual both a big help.
I'm trying to keep it driver orig.
I'd like young car enthusiasts to see what it looked like from the factory
yet still be driver friendly.
I do not have nearly the $ or time to go full blown show quality resto.
A little at a time a guess.
Thank you both again
Marshal

 

You can make your own 'vacuum advance pipe' by getting some aluminum tubing of the right (or close) diameter (about 1/4" or slightly less) and bending it to the shape you see in the AIM. It will work just fine.

 

Well I checked the rear of AIM in options section.
I found the RPO L-36 engine but no pics of spark pipe?
In the general engine section it shows spark pipe with a part#
but its only specified for 19400 engine? not all appications.
Glad you pointed out the options section in the back
Alan. I didn't find specifically what I was looking for but did
see allot of other assembly drawings that were helpful to my engine
option.
If anybody had a spark pipe from new on a L-36 please let me know.
Thanks again,
Marshal

 

7T1,
just saw your posting after typing 2nd response.
Thanks I may have to do that if unavail.
Dr. Rebuild has them listed. He doesn't have 1 for 68? Odd.
I'm still trying to determine if it called for one
Marshal

 

I found what I was looking for finally
With the help of this forum you guys lead me to the right church
and I found the right pue after that.
In the 1968 AIM pg H-316(Options Sect) Rear of Book,
under the RPO C-60 AC install, they show the proper placement
for the Production Spark Hose placement.
So you need to be familar with your aim manual on the assy line.
The line is inserted in a 3 way tee in the rear of the intake manifold.
The 3 way tee is used for the spark advance(Prod Hose) as GM called
it, the RPO J-50 Pwr Brake booster vacuum line,(which I also have), and
your vacuum source line for the filter for the headlight/wiper functions.
There is a specific pic for L-36 RPO and L-68 RPO.
Didn't figure it to be under AC section
So I did not have a section of hose and stand pipe with AC an pwr brake options. All sources went into a 3 way tee in the rear of the intake manifold. Front of Quadrajet in pic shows a plug insert for manifold vacuum port.
I know I over explained myself but figured it may be of some assistance to others.
Thanks for pointing me to the options sect in the AIM guys
A little more time in the library with the AIM in my lap and I'll know where GM hid this stuff.
Marshal

 

Hi Marshal,
Thanks for the update.
You're right!, the AIM certainly can be a puzzle. There's an incredible amount of information in those pages, but finding it isn't always easy.
Regards,
Alan

 

Alan,
thanks for pointing me in the right direction.
I worked for GM in 1980-84 at an Olds dealership in the parts dept.
We still had the old blue books. It took some on hands to get comfortable with where the parts were per groupings in the books.
Trim parts were the worst to look up. Most times we ordered the wrong color for the customer the 1st time
Did help a guy restore a '60's era 442 from start to finish at 17 y/o
that was pretty cool.
Marshal

 

I am not sure about 68, but the steel line was only used on the 69 L36 without factory AC.

I had to argue a bit with the judges at the NCRS regional in kissimmee that the untouched original setup on my car was correct. They had never seen the 3 way tee off the manifold and were telling me it was not original. The judging manual states that all cars used the steel lines, but there is a small diagram in the assembly manual under the C60 AC section that shows the L36 tee and a prod spark hose. I didnt have the assembly manual with me and the judges wanted to move on and and mark the deduction. I actually had to call over the 68-69 team leader to clear up the issue.

Gary

 

Gary,
thanks for sharing your experience with all of us.
Maybe, I just caused a ripple in the '68 judges manual
I'm not planning on having mine judged at this juncture in my life.
I did all the show stuff with my classic Norton Commando and received
numerous 1st place trophies. I think I've gotten it out of my system.
The car just kinda came along during a search for a corvette last August. I guess it was meant to be?
What I do want to do is be able to open the hood at a cruise nite and show young guys what it looked like when it left Detroit.
I'm not so concerned with chalk marks on the frame which in all honesty would have worn off a year after the car left the show room.
I have the greatest respect for those that commit and complete the
endeavor such as Alan. His car is a testimony in restoration and detail.
The '68 was a one year wonder on allot of things I'm learning.
It seems like a carry over from '67 and allot of changes before/during
'69 too.
Your car looks to be an early '69.
As soon as you introducde options it looks like the rules changed.
I would imagine my car with pwr brakes & A/C would have had the 3 way tee installed along the assy line somewhere?
You would have to know all option configurations before judging a particular unit. I'm kinda of a novice Norton Commando self proclaimed expert. I can tell you if it belongs on there from England or not.
Not allot of options on bikes. Now if you have a police model the rules change see what I mean. I also think allot of parts clean up went on as they never threw things out intentionally. Having early C-3's we both find the refinement process still evolving in my opinion.
I'm glad you challenged the judging. They would look silly telling a guy/gal there car is not orig. only to find they were the orig. owners and took delivery of same in that configuration.
Study you AIM!!! I'm still learning
Marshal

 

hi,
68 L36 (427-390HP with P/B no A/C)
i have follow up question:
will i be correct installing part#4020 (from attached paragon catalogue) and capping my Q-jet as per assembly manual ?
thnx,
alex

 

Hi alex,
The fitting you're pointing at is also usually the source of the vacuum for the wiper door and headlight systems.
Does your car still have those systems and are they still vacuum operated?
Does you car have an operating pcv valve and is there a pipe on the carb that you're planing to use?
Regards,
Alan

 

Alan,
thank you for propt reply.
yes i do have vacuum operated wiper door and headlight system (not installed yet). attached is picture of my engine form front.
i used arrow where hose from AID inlet connected to Q-jet

my car only has following options:
======================================== ======================
A01 GLASS - TINTED - ALL WINDOWS
G81 DIFFERENTIAL CARRIER - POSITRACTION
J50 VACUUM POWER BRAKES
L36 V-8 ENGINE - 427 CU.IN. - HIO-PERF 385/390 H.P.
M21 4-SPEED TRANSMISSION - CLOSE RATIO
N40 HYDRAULIC STEERING
PT7 F70-15-4 PR TIRE - SPECIAL NYLON - WHITE STRIPE
U69 RADIO - AM/FM - PUSH BUTTON
V48 ENGINE COOLANT - INCREASED PROTECTION (ANTIFREEZE)
W84 ADDITIONAL FUEL FOR DELIVERY
======================================== ======================

so if i look at vacuum diagram (from Paragon) i have to install 3-way manifold connector?
- one to distributor
- one to vacuum tank via
- one to power brake booster

bit confusing for newbie

thnx,
alex

 

i have installed #2277 (2-way)
shoudl i go for # 1364 (3-way ) or # 2278 (3-way) instead?

 

Hi a,
It appears the #1364 would be the good choice for you.
I think the #2276 is for use with a tri-power engine on which the rear carburetor 'crowds' that fitting….thus the pipe at the top.
The pcv valve connection is typically at the base of the carb where your arrow points. It's typically a large hose so be sure the nipple in the base plate is large enough… it typically is.
Regards,
Alan

Marshal has a 68, perhaps he'll post his thoughts!

 

My 69 late build (Oct 24) L36 with power brakes and no AC has a 2 prong vacuum connector on the rear of the original snowflake intake manifold. One side goes to the brake booster and the other to the vacuum filter and on to the systems (wiper door, headlight doors and heater controls). The distributor vacuum advance connects to a short piece of vacuum hose then the formed metal tube which runs down the passenger side of the intake manifold/valve cover then to another piece of vacuum hose to the front left port of the carb. The AIR pump is connected to the right side port on the carb. The only other vacuum port on the original 7029215 carb is the the center front port for the PCV valve. Mine is the original engine, intake, carb, distributor and smog pump.
Below is the only pic I have so please disregard the vacuum gauge. The smog pump connects to the port where the vacuum gauge is connected and you can see the metal vacuum advance tube starting to the left of that gauge.

 

Hi a,
There you go!
A really nice photo from CG!
But now I'm confused…. to you need actually 2 or 3 nipples on the fitting?
Regards,
Alan

 

CG thank you for nice picture !

Alan, i think your are correct : it has to be 3-way
as per assembly manual (page H316 top left corner)
part 2 = 3891526 -L36 WITH RPO J50 or 1364 from Paragon catalogue.
my 68 carb has that front pipe capped and distributor vacuum advance will be connected to that 3-way manifold inlet connector.

will try this setup over coming sunday and post update.