68 Cadillac MM Combo (Restore thread)

[John ED Renstrom]

here is what I did to mine to help correct the problem. slip some insulation around it were it comes close to the pipe trim the splash apron to get more air to it and made sure that it is not touching anything. we will see 97 today out here but the humidity has dropped to 33

 

[Blake Sherwin]

Thanks for the pointers. I had wrapped some "cool tape" around a few segments awhile back but it looks like it fell off. It is tight against a radiator hose at one point, so much that i cant even access it.

I am taking half a day off work tomorrow to try to get this ready for saturdays parade. Im hoping i can request to be at the back, so i dont hold the parade up if i stall.

 

[John ED Renstrom]

Took my test run. I did dump a can of seafoam in it also. But we did ok.

 

[Blake Sherwin]

Today I am getting the oil changed, I am going to try out the Royal Purple. Also going to swap back to a non-return filter and see if the bog still exists. If it gets rid of the bog I have read 4oz per 20gal of marvel mystery oil added to the gas tank can help a little with vaporlocking. May give that a shot and test results

 

[John ED Renstrom]

Try the oil first before you swap the filter. Do one thing at a time there is nothing in the filter that will do that. The bog might be excessive fuel with the aftermarket carb.

 

[Paul Steinberg]

Today I am getting the oil changed, I am going to try out the Royal Purple. Also going to swap back to a non-return filter and see if the bog still exists. If it gets rid of the bog I have read 4oz per 20gal of marvel mystery oil added to the gas tank can help a little with vaporlocking. May give that a shot and test results

I don't think that changing to Royal Purple oil is going to be of any benefit to you over using a regular oil. I would only recommend Royal Purple oil to someone that was starting out with a new car, with very close engine tolerances, and even then, I don't believe that it will give any additional protection over a synthetic oil. For your car, using a synthetic oil will be of no benefit, and might be more of a detriment since the synthetics are thinner, and tend to cause leaks in older cars. Just stick with a 10W30 or a 15W40 dino oil, and change it every 3000 miles. Also, add the ZDDP additive to the oil for peace of mind. If you want to avoid the ZDDP, then buy Valvoline Racing Oil which has the high levels of ZDDP in it. As for Marvel Mystery Oil helping to prevent vapor lock, well, it can't hurt, but I would have serious doubts of it doing anything. Vapor lock is the gas changing to a vapor, and that is a result of heat. This is why GM added the return line, to prevent the fuel from becoming heated, since it is constantly being recirculated to the fuel tank, and then being pumped back to the carburetor. If you want to spend money on your car, you should consider getting the original carburetor back onto that engine after having it rebuilt by an experienced Rochester Quadrajet carburetor rebuilder. I can give you a reference should you decide to have it done. The car will never run as well as it did on day one, with aftermarket one size fits all parts.

 

[Blake Sherwin]

People also swear adding a little diesel works, but I really dont feel right adding diesel. I just feel like thats a really bad idea, so i will not be doing that. I was just looking for a temp fix to improve my chances of not vaporlocking in the parade. Originally I had decided not to do that parade for fear of vaporlock, but then my wife apparently ordered these american flag "bunting" things she wants me to hang in the window, so I had to register.

On the bright side though, if I do vaporlock im not going to die, and the car will be fine. The worst that will happen is I will suffer slight embarrassment, but I will survive. I am trying to not get too worried about it. It will be nice if they allow me to hang in the back though

 

[Blake Sherwin]

I don't think that changing to Royal Purple oil is going to be of any benefit to you over using a regular oil. I would only recommend Royal Purple oil to someone that was starting out with a new car, with very close engine tolerances, and even then, I don't believe that it will give any additional protection over a synthetic oil. For your car, using a synthetic oil will be of no benefit, and might be more of a detriment since the synthetics are thinner, and tend to cause leaks in older cars. Just stick with a 10W30 or a 15W40 dino oil, and change it every 3000 miles.

Now you have me worried. I trust you guys more than I trust my googles, although my google-fu is strong I may take that advice and return the royal purple. My oil pan gasket already leaks as it is.

 

[Blake Sherwin]

Well i put another 5 dollar filter back on like before and it runs great. Puzzling, maybe somehow the return line was preventing enough gas getting to it? I want to eventually get this functioning the way it was intended, but for now i will run this filter, so that its drivable.

Getting oil changed now

 

[John ED Renstrom]

try blowing threw the filter. bet the made in china one has a restriction. nothing to do with the return line it just allows excess presser to return. though it was strange you found one for the car. which side says inlet or what way does the arrow point?

 

[Blake Sherwin]

Installed it with the arrow pointing to the carb. The new plastic one i put on today simply says "to carb" with an arrow. Definitely on right though. Engine is smoother though after that oil change. I had put seafoam in the oil some time ago so the oil was thin, black and gritty before.

Took Pauls advice and didnt do royal purple. Shop put high mileage oil in instead which im fine with. Yes i paid for my oil change. When it comes to oil id rather not mess with it.

 

[Peter Grave - Deceased - 1938 - 2022]

Smart move when you are a shade tree mechanic (no offense ment you are an eager student showing much progress). Thing is the drain plug is real easy to cross thread and strip thats why self tapping drain plugs are sold. By having the pros do it if they strip it its on them a good move on your part. Keep plugin you are making progress.

 

[John ED Renstrom]

The question was could you blow threw it with out restrictions. The only reasion it would not work is it is defective. Something inside restricting the threw flow.

 

[Paul Steinberg]

If the return line were clogged, then it would act like any other fuel filter. If the filter itself is clogged, then it will act like any other clogged fuel filter. If you have never cut open an old filter and visually analyzed its contents, you have no idea if your fuel tank is full of sediment, or other "crap" that clogs fuel filters. Some of the clear filters push the fuel from the outside to the inside, where it then enters the carburetor. On these types of filters, you can clearly see the debris. Some, on the other hand, operate in reverse, and you only see the clear filter, so you have to cut them open and examine the paper filter material to determine if there is a problem lurking in your fuel tank. After 50 years, you have no idea how much crap can accumulate in a fuel tank. The only advantage of the new ethanol laced gasoline, is that the problem of water in the fuel is greatly diminished. It has also led to another problem, called phase separation.

First picture, is after the bottle of old gasoline has been sitting for a while

Second picture, I have shaken the bottle to mix the contents

Third picture, taken immediately after shaking, to show that it settles out quickly.

The gasoline that is always at the top, is stale gasoline that doesn't burn well. The contents that are at the bottom of the bottle will not support combustion in the engine!

 

[Peter Grave - Deceased - 1938 - 2022]

Sounds like perhaps unhooking return line and blowing back to tank with compressed air might be a good move. Blowing back the fuel line not a good move unless line is disconnected at tank as it will blow the filter sock off the pickup in the tank. I hate making off the wall suggestions but an electric fuel pump installed at the tank may be the cure. Now 68 Cadillacs never needed this when we were driving them as everyday cars. But now thanks to the government getting into petrolium products and adding corn to gas perhaps this is needed. Opinions comments from others??

 

[Blake Sherwin]

Thanks everyone. On the bright side the parade went great and i did not vaporlock.

 

[John ED Renstrom]

the nice part of the CC tank is there is not sock just a internal line that goes to the canter sump. the return line on them will return to the right side close to the front. a pipe goes from the fitting to the top of the taink. here is the bottom view of the tank in now George's 68. it is a none ac car so the return like is just plugged.

she looks good rolling down the street. we were closer I would show you have to make it shine. just because the paint is old doesn't mean it will not shine.:thumbsup:

 

[Paul Steinberg]

Ed... every fuel tank has the "sock" on the end of the pick up tube. You might have been mislead, by not finding one on a particular car, but trust me on this one, every fuel pick up tube has a "sock" to keep the bigger chunks of debris from making it into the carburetor. If it isn't there, it needs to be replaced, and most likely it can be found swimming at the bottom of the tank.

 

[Blake Sherwin]

Thanks that info is helpful. When i have the time again i will see if i can pull that off and blow through it. After looking at the picture, my car was fitted witg dual exhaust at some point so that other pipe could be running past those lines as well, heating it

 

[John ED Renstrom]

Ed... every fuel tank has the "sock" on the end of the pick up tube. You might have been mislead, by not finding one on a particular car, but trust me on this one, every fuel pick up tube has a "sock" to keep the bigger chunks of debris from making it into the carburetor. If it isn't there, it needs to be replaced, and most likely it can be found swimming at the bottom of the tank.

Don't bet the farm on the pro car/58 standard tank. The pick up tube goes from that that fitting up to the top of the tank and straight down to that sump in the center. It rides about a 16 of a inch off the bottom in the center of it. I did not find a sock in either of the two i cut up.