[pfilean]

lilabner

Did your car with A/C not have a factory vapor return filter? Or was it an under dash add on conditioner which I don't think got the vapor return as part of the kit. Such a kit would have required adding the return line back to the tank and also adding the vapor return sending unit in the tank and I don't think it was included. At least my 61 shop manual for installation of the "Cool Pack" units does not mention it.

I didn't realize there were so may cars with the over the valve cover vapor return. I thought the factory pipe always ran down past the fuel pump. I have seen other pictures that show it like the pictures you added but didn't think it was so common. Unless that was an earlier solution and the sharp U bend and running down past the fuel pump was the later solution. Most information seems to show the routing past the fuel pump for 63-maybe 67 applications.

If your first try at putting in a vapor return was just to add a "T" after the filter it would bleed a lot of pressure off and send fuel back to the tank. Even with only a 1/4 return line. The filters have a small reservoir above the filter element where the vapor outlet is a little higher than the fuel outlet which allows the vapor to separate. Then there is a very small hole (maybe .05 - it's mentioned in other threads) that restricts the amount of fuel that can be forced out through that line. That keeps the fuel pressure high enough to supply the carbs. Later fuel pumps which had the vapor separator built in work similar.

Was not aware Inline tube had those lines. Will have to check out their offerings. I had tried Right Stuff Detailing which has some fuel lines but lately I have had a hard time getting information out of their web site.

[War eagle]

Very interesting Lilabner. I have also done battle with the 'vapor' lock with my high school car years ago. Then the fix was tin foil wrapped around the engine compartment fuel lines with clothes pins. Worked. That and a spacer under the carb to stop boil out which then leads to vapor lock sometimes. Glad you have it fixed. Maybe something you overlooked may have been the filter. A see thru view of the vapor diverter style filter from the AC dealer catalog, shows that fuel flow only goes back to the tank when the carb has had its fill. A spring inside the filter manages the flow. Maybe the diverter spring failed in your filter which of course would result in low pressure. Your restrictor is just working the fuel pump continually at pressure.

pfilean I do see a secondary wire going to the original sender. Still, at least in my mock-up with the original fuel filter brkt, very little room is available for the sender lead. Your lower mount of the filter would help but I am stuck with the original.
Also your 61 fuel filter with factory A/C is listed as 1962-61 ALL GF-73 in the AC Dealers Catalog 1-64

[pfilean]

Yes the factory listing is for the GF73. But I was able to score the GF98 first and am still using it. Now I have two extra 73s just in case they are ever needed. The 98 is not quite the same size as the 73 but close enough to work.

Interesting to note on the spacer under the carbs. My PO always thought he had vapor lock problems and tried various things including scrapping the mechanical pump in favor of an electrical near the tank. But that pump was wire on it's own switch not through the ignition and mounted so it hummed . I couldn't stand it so bye-bye. He also had a 64 manifold which had PCV fittings screwed into it. I wanted to be more 61 correct and changed to a 61 manifold which needed an factory optional vacuum takeoff spacer under the center carb with accompanying spacers under the end carbs to keep them all level for the big air cleaner. That and the vapor return and I don't think I have had a problem since.

[War eagle]

Speaking of scrapping, I will use the repop 98 for some other project just as soon as I can locate an original. Maybe the last one you scored on was the last GF-98 and that's why I can`t find one..

[lilabner]

Originally Posted by pfilean

lilabner

Did your car with A/C not have a factory vapor return filter? Or was it an under dash add on conditioner which I don't think got the vapor return as part of the kit. Such a kit would have required adding the return line back to the tank and also adding the vapor return sending unit in the tank and I don't think it was included. At least my 61 shop manual for installation of the "Cool Pack" units does not mention it.

I didn't realize there were so may cars with the over the valve cover vapor return. I thought the factory pipe always ran down past the fuel pump. I have seen other pictures that show it like the pictures you added but didn't think it was so common. Unless that was an earlier solution and the sharp U bend and running down past the fuel pump was the later solution. Most information seems to show the routing past the fuel pump for 63-maybe 67 applications.

If your first try at putting in a vapor return was just to add a "T" after the filter it would bleed a lot of pressure off and send fuel back to the tank. Even with only a 1/4 return line. The filters have a small reservoir above the filter element where the vapor outlet is a little higher than the fuel outlet which allows the vapor to separate. Then there is a very small hole (maybe .05 - it's mentioned in other threads) that restricts the amount of fuel that can be forced out through that line. That keeps the fuel pressure high enough to supply the carbs. Later fuel pumps which had the vapor separator built in work similar.

Was not aware Inline tube had those lines. Will have to check out their offerings. I had tried Right Stuff Detailing which has some fuel lines but lately I have had a hard time getting information out of their web site.

My car did not come with AC. I bought a unit from Steve At Indiana Pontiacs. Everything was good, but the evaporator. I found that out the hard way. I bought a 62 A6 compressor on ebay, 4 seasons rebuild, and brackets from Steve first. Had the same problem. Had a new evap made, problem solved. At some point I will put the A5 back on.
I didn't have the vapor/starvation problem again until I built a 421 and installed it. Pulled the tank, it looked ok, but the fuel line was rusty inside. I put a 3/8 hose in place of it and it ran much better, so I replaced the main fuel line. Inline Tube again. Was only having the starvation cold now. The filter was clear, new fuel pump, tank sender with return was clear. Sock filter was brown, so I took it off and put an external inline filter coming out of the tank pickup. New 98 engine filter. Problem seemed solved. The pictures I posted are not my car, only some others I found with the line showing. I had a new 62 back in the day with AC, and then a 61 Bubbletop AC in 64, but can't remember how they were. I just never had a problem. Being an ocean race boat and Porsche mechanic for the last 46 years I am quite familiar with fuel problems and the fixes. I will also say using Duracool 12A is the best AC enhancement I have ever made. Forget 134A, but if it works for you, don't change anything. Duracool is cheaper also. Enclosed is a picture of my engine with vapor line. I may change it around in the future.

[pfilean]

We have moved this thread away from the original question as the b-body has become a large part of the discussion. In the 62-66 Big Pontiac forum 65WJ has suggesting he may be able to check on the vapor return routing. I for one would like to see if he can come up with what was the various year of routing the vapor return. lilabners pictures certainly make me think I have been wrong about how it was done in the 61-62 time frame and I would like to know the answer. When I first saw some cars with that over the valve cover routing I had a hard time thinking it was factory as it looks like a long unsupported return pipe I didn't think the factory would do. Maybe time will get an answer.

[War eagle]

Group 3.890 in my 1964 MPC shows 61-64 P/8 with circulair and just below shows 61-64 T/8 A/C. Description: Hose vapor return hose (22 long). Why this would not be the 10in length as shown in another section is a mystery. The 66 MPC does not show this reference. The part # for the hose is 537426 and also indicates AR (as required).
There are several references to "Vapor Separator PKG." for P/8 from 58 up. I would have thought this PKG. was for the add on A/C but the description does not indicate that exclusively. Never the less, the over the valve cover return hose sure looks awkward and almost an after thought. Something added on to complement added on A/C. With 6 to 8 lbs pressure, I would have thought there would have been a support or bracket to securely route the line and hose. Lilabner has his return line within a fraction of an inch to the intake manifold exhaust crossover. I`m thinking gas and extreme heat don`t mix for a number of reasons..

[lilabner]

I posted some more pictures for 61-62 cars in the 62-66 big car forum. there are at least 4 maybe 5 different cars in the pictures in the two forums. That seems to me to be proof the 61 & 62 cars all had over the valve cover lines. They are unsightly and a PITA to work around. Seems like they had a better idea in 64. But that's how it's supposed to work.

[John V.]

Originally Posted by lilabner

I posted some more pictures for 61-62 cars in the 62-66 big car forum. there are at least 4 maybe 5 different cars in the pictures in the two forums. That seems to me to be proof the 61 & 62 cars all had over the valve cover lines. They are unsightly and a PITA to work around. Seems like they had a better idea in 64. But that's how it's supposed to work.

Same conclusion that I was reaching. Factory A/C was still pretty rare in those days, so I don't doubt even the factory arrangement was a bit crude at first.

Originally Posted by War eagle

Group 3.890 in my 1964 MPC shows 61-64 P/8 with circulair and just below shows 61-64 T/8 A/C. Description: Hose vapor return hose (22 long). Why this would not be the 10in length as shown in another section is a mystery. The 66 MPC does not show this reference. The part # for the hose is 537426 and also indicates AR (as required).

We've had the discussion about what constitutes the '66 MPC before. Mine printed Aug. '65 and dated "Effective October 1, 1965" shows "1966 Pontiac Chassis Parts Catalog" on the spine and the first page C-1 shows same Title.

It has a great many service parts, illustrations, and references to '66 Model Year cars.

You mentioned yours shows Effective October 1, 1966 but no reference to '67 cars or the '67 Model Year. What is on the Title page?

I mention this because I also was looking at Gr. 3.890 yesterday and saw reference to Vapor Return Pipe Hoses, a line item for '61-'64 P/8-T/8 A.C. listing the hose as p/n 9779575 described as 27" long.

And another line item for '65-'66 P/8 A.C. showing the same p/n and hose length.

Only the '61-'64 line item is noted A.R.

I interpreted this piece of hose to be cut to suit, not a specific service part of specific length.

Possibly for the '65-'66 P/8 it was a specific service part since it isn't noted A.R, but I suspect it was still intended as cut to suit.

And no listing for the '65-'66 T/8, not sure why, I suspect they just inadvertently neglected to list the application.

In any event, I don't think you can draw anything from this listing, whether for the 27" long I found or the 22" long you found in the '64 MPC.

Except perhaps for the fact that from the Illustration of the '64-'65 A.C. fuel system, there are 3 separate pieces of 1/4" rubber hose needed to make the run from filter back to tank, 15-1/2" at the tank, 10" from pipe to pipe, and the short piece from filter to pipe that the length is not identified. But previously I noted it looks to be the same 1-1/2" length as noted for the adjacent filter to carb pipe hose. If you accept that, add the 3 lengths together, and the total is 27".

In Gr. 8.962, PMD also serviced 1/4" rubber hose in bulk, as a 25 ft. long roll.

Originally Posted by War eagle

There are several references to "Vapor Separator PKG." for P/8 from 58 up. I would have thought this PKG. was for the add on A/C but the description does not indicate that exclusively. Never the less, the over the valve cover return hose sure looks awkward and almost an after thought. Something added on to complement added on A/C. With 6 to 8 lbs pressure, I would have thought there would have been a support or bracket to securely route the line and hose. Lilabner has his return line within a fraction of an inch to the intake manifold exhaust crossover. I`m thinking gas and extreme heat don`t mix for a number of reasons..

I get the impression that the earliest factory set-ups used a fuel filter with some sort of separate vapor separator arrangement and starting with '61, for A/C, the GF-73 fuel filter incorporated the vapor separator.

Regardless, the over the valve cover routing may seem crude but evidence does suggest that it was the factory arrangement.

Field installations may not have included the vapor separator system at all. I think somebody already mentioned that trying to add a return line all the way to the tank would have been a bit of work, including replacing the fuel tank sender unit. Unless a vapor lock complaint was received, they may have just ignored it for field installations.

They didn't service the steel pipes, only serviced them in 25 ft. coils.

Logically, gas and heat wouldn't mix, but I'm not sure that adding a vapor return line was always necessary for a field installed A/C. Did the aftermarket A/C installers install a vapor return system?

[lilabner]

The return pipe I got from Inline Tube for a 61 stubbed out just aft of the brake MC Tee. You had to make the upper line yourself out of 1/4" pipe. I bought a galvanized coil for this. You cut a short piece of hose to join the two pipes together, I put a clamp on the fender well, ran it the way one of my pictures were showing, then another hose to the filter. the picture I chose had the pipe running along the inside edge of the VC. This kept it closer to the MC. That seemed to me to be a better way than running across a big space. This is the end result.

[War eagle]

The fist page Effective Oct. 1, 1966 Pontiac Chassis Parts and Body parts

The following page; Pontiac Chassis Parts Catalog, Revision Schedule, Revision Number 10 (effective with Parts Release and Change Notice 66-8 dated Aug. 1, 1966)


On the page that has 'Contents' and below that 'Parts Data Index', 1966 Pontiac Chassis Parts Catalog, Oct 1,1965


Nothing for 67 however late this appears. All 6 inches!!!!

[John V.]

Originally Posted by War eagle

The fist page Effective Oct. 1, 1966 Pontiac Chassis Parts and Body parts

The following page; Pontiac Chassis Parts Catalog, Revision Schedule, Revision Number 10 (effective with Parts Release and Change Notice 66-8 dated Aug. 1, 1966)


On the page that has 'Contents' and below that 'Parts Data Index', 1966 Pontiac Chassis Parts Catalog, Oct 1,1965


Nothing for 67 however late this appears. All 6 inches!!!!

Okay, so sounds like the same book that I have but with later revisions. I also have the matching '66 Body Parts Catalog, I assume you have that also.

Mine doesn't have a Revision No. page in it, apparently original issue. I thought I recalled seeing a few pages with a Rev. date on them but after scanning thru and finding none, I think I may have seen that in a 1960 MPC.

Dealers could subscribe and get revised replacement pages. This is explained on page C-3. Otherwise the dealer would have to post his own changes manually as they were announced.

Sounds like yours may have been a general revision to the book or else Rev. 10 included certain pages that the Dealer inserted. Either way, your book is updated. My book must have come from a Dealer that didn't manually post changes, since no real evidence that any changes were manually posted. Perhaps he did subscribe but failed to insert the revised pages in his book when he got them. Either way, looks like my pages are from the original issue and will differ somewhat from your revised book.

[pfilean]

All this late discussion got me looking closer in my MPC Effective Oct 1 1966. And I think John V may have it right.

Same conclusion that I was reaching. Factory A/C was still pretty rare in those days, so I don't doubt even the factory arrangement was a bit crude at first.

In MPC 3.890 there is listed for 58-59 All AC Exc. FI Union fuel filter to fuel vapor return. There is a reference to 8.963 which makes that piece a flared tube to flared tube union. So in that year there must have been two pipes. The pipes are not defined.

In MPC 3.890 for 59 All AC Elbow fuel filter to fuel tank vapor return pipe (1/4 x 90). 8.963 shows that to be a street ell for flared pipe to NPT. SO there must have been some pipe in the system. But the pipe is not defined.

In the 57-60 time frame I think the filters were all the glass bowl type and maybe the GF-53 version as listed in MPC has some vapor separator included. Although there is also listed for 59-60 some GF63 vapor separator packages.

And notice that for 61-62 P/8 Circulaire AC the GF73 filter is listed. But as it is listed for Circulaire it must mean that the under dash "Cool Pack" did not get the vapor return filter. And the installation instructions never seem to mention one.

Some of lilabners pictures show a support for the hose off the filter that is similar or the same as the support used for PCV on the passenger side. In MPC 3.890 there is listed for 62 only such a support. So I think the pictures with the support are likely 62.

Bottom line. Although the evidence seems to point to pre 63 using an over the valve cover routing it is hard to say year by year just how it ran, lilabner's pictures don't seem to show exactly the same routing twice. It was crude and awkward and probably screwed up by the first mechanic who had to remove the valve cover. That likely explains the MPC reference to coiled tubing that each mechanic redid to his own whim. He was no doubt ticked by then that he had to put back something he messed up and do it outside the flat rate manual time. So by at least 63 the factory found a better way and made the tube with a tight U bend that is hard to reproduce.

Here is a picture of a 58 that I think had AC but I can't distinguish a vapor return in the picture. Unless it is down there on top of the pump.

[John V.]

pfilean, not so sure that '58 shows A/C.

That big honkin' thing where the compressor would go is the generator right?

Is there a telltale that makes you think A/C?

[pfilean]

The later years moved the generator up to allow the compressor to mount below it. I'm guessing (Yes-guessing) that may have been the case in 58. Really would need one of the diagrams showing how the belts were arranged to know for sure. Also in the background it looks like glossy black blower casing like AC might get. But some of the early AC were not arranged like 61 and later were. I don't think they were in the trunk. But the old picture is not good so I just "think" it has. AC.

[John V.]

Okay, no problem. Since the vapor return is not in evidence, not sure what we can make of it even if it is a factory A/C car.

I did look at the other thread, saw some interesting pix.

Tried to find some engine shots for any '60-'62 Pontiacs with factory A/C on the web, struck out.

[8LUG]

MPB 9-15-64 SHOWS 9779575 1965 P/8 HOSE vapor return hose 32" revised 3-1-65

[John V.]

Weird, same p/n but described as 27" as of 10/1/65, and actually earlier as the book was printed before the effective date. Did they really shorten it or was it described incorrectly? Doubt we'll ever know unless somebody turns up an NOS package.

[lilabner]

Originally Posted by pfilean

The later years moved the generator up to allow the compressor to mount below it. I'm guessing (Yes-guessing) that may have been the case in 58. Really would need one of the diagrams showing how the belts were arranged to know for sure. Also in the background it looks like glossy black blower casing like AC might get. But some of the early AC were not arranged like 61 and later were. I don't think they were in the trunk. But the old picture is not good so I just "think" it has. AC.

No belt for AC showing on the crank pulley

[pfilean]

I know it's a lousy picture. Hot Rod wasn't doing full color back then. I think the generator position is high enough to have the compressor under it. It moved up from a lower position with AC. I remembered the belt routings were in the parts book. In 58 it was like 61 and a number of years. The belt only ran around the crank and compressor. In any case what ever the vapor return routing may have been it is not obvious. I guess they were trying a lot of ideas until they thought they had it right.