Hey fellas, I though I had the connections all figured but happened to look at the Ames catalog yesterday and saw 5 colored vacuum hoses coming as a set.
1. Yellow stripe 2. Red stripe 3. Green stripe 4. Blue stripe 5. White stripe
I have a 400, auto car, and know the yellow that connects to the passenger side of the Quadrajet in plugged. So yellow hose is not used.
So the 3 vacuum lines that are used in my case, the red striped one goes to the rear of the carb fitting where the power brake vacuum line is connected.
The next connects to the right front of the carb. Does this have a color?
The last one connects to the distributor -what color is that one?
I have not seen any documentation that shows the stripe colors for all five of the original TVS vacuum hoses. The manufacturer of that vacuum hose kit must have some information showing the three missing hose stripe colors.
Assuming the hoses are correctly assembled in the kit's rubber plug, the function location of corresponding TVS connector should help you find the colors.
Could you list the locations of each color in the rubber plug?
Separate related subject:
I have studied and thought about the five verses three hoses for some time now. Although Mr. Good Wrench did the T-2 mod on my '68 400HO during its warranty days, I still wonder whether the 400 Firebirds were meant to be included in the 5 to 3 port change since they were excluded from the Service Bulletin. I've been considering leaving the 3 port mod functionally yet cosmetically have a full 5-hose/port in place. (I have all the correct new hoses.)
Ames states they have instructions for the installation, but I don't want to spend $120 for the set as I don't need it.
If you look at some 68 Pontiac documentation it shows the trans tube that connects to the front of the q-jet is a white striped hose. Not sure if Firebird is the same. As I said, the red striped as shown in the hose routing of the manual goes to the rear of the carb, yellow striped is not used and I'm not sure about the green and blue striped hoses.
The only application I found that has all 5 hoses connected are the 4 speed cars. Auto only has 3 hoses connected and 2 plugged.
Here are the Ames color coded hose, all I'm trying to figure out is what colors connect where. From what I've seen, it appears there are only 2 colored hoses in the 5 shown, but Ames sells 5 colored coded hoses individually which made me think all 5 hoses where color coded originally.
I recalled an article from Pontiac Enthusiast magazine (Vol. I No. 2) It also only mentions the yellow and red hoses.
Excerpts from the article, '68-8 Thermostatic Vacuum Switch by Peter Serio
"A manifold connector in the vacuum hose harness to the TVS is used to prevent the hoses from being installed improperly. Note that some of the vacuum hoses in the harness have color-coded stripes running on the supply lines to the TVS. The red-striped hose is manifold vacuum, and the ported vacuum is routed through a small steel pipe forward of the carburetor. The yellow hose (used in 1968 only) is the retard-at-idle-speed vacuum supply."
"There were two different hose harness assemblies used, depending on the year of the car. In 1968 only, with the dual-port vacuum-advance unit attached to the distributor, the idle speed timing is retarded 10 degrees to reduce emissions. After the '68 models, all distributor-advance units were the standard single- hose-connection style. All the 68s use the 5-hose vacuum harness, while the 69 V8's and 71 455 HO make use of the 3-hose type. The two extra hoses on the 68- only harness are the idle-speed retard feature."
I checked the 1969 Assembly Manual (sure wish one could be found for the '68s), It being only a three port TVS, the only hose, of the three with a color stripe is the red stripe one. No colors mentioned for the long vacuum advance or short partial run to the front of the Quadrajet.
It seems that was the correct way. As mentioned the yellow striped hose was eliminated on auto cars, so red and 2 solid, ribbed black hoses for dizzy and front of q-jet was correct. It is hard work to find the right info out there, especially when you think most Pontiac cars in 68 were set up and built very similar, but that has proven to be incorrect. That is how I found a white striped hose going to the front of the carb (same as the hose to the vacuum pull off, which was not the same on Firebirds. Thanks for your help!
I'll try and find the article the gm engineer who built the 400 firebird ho motor wrote. even got to speak to him on the phone great 2 page tech read on how the vacuum lines connect and how the setup helped prevent overheating. Great guy to talk to. you might find it in a Google search. he describes how it works to reduce heat. I went and put it back to original per his article and yep never overheats anymore. if my uncle who I gor the car from was still with us I would have kicked him in the button as like alot of the backyard mechanics in 68 removed them thinking they were like emissions and would reduce performance. and all it did was cause my Uncle to try bigger and bigger radiators. I'm now using the original factory radiator and I live in az and last summer at 118 degrees it never overheated. so glad I found not just the article but the engineer so much info not in the books. now I have to figure out why she suddenly started stalling at fourth today. new pump lines clean tank all of that same issue tomorrow I'm gonna replace the coil as it seem like power to plugs drop. we'll I will get the article tomorrow and post it I meant to do it a long time ago. I think it would help alot of folks with hot or overheating 400 HO's
I'm also in AZ and never had any problem driving my bird without any vacuum advance. I just use the mechanical advance for all the engines i build. There are more factors that contribute to an engine that supposedly runs hot. So what are your initial and total timing numbers?
