WPVT

I bought a rebuild kit from Then and Now. It's an easy job, I think they have instructions that come with the kit. The tricky part is getting up the nerve to pry the valves out with a screwdriver. They do pop right out, though. I actually had them on the phone when I did mine....just for moral support !

Thanks. I can also remember when one could go to a spring repair shop and have springs rebuilt. The only spring shop left within 100 miles is pretty good, but they are too busy to fool around with an old pickup truck, and apt to resort to pragmatic fixes. I do have a general repair shop, however, not too far away, that does decent, careful, work on old vehicles. To the extent possible, I try to bring them the right parts along with the truck when I bring it in. Not to save money, but to save them time. They can't spend hours on the internet tracking stuff down, while I can (and do). They appreciate it, provided I get the right stuff. It means they don't have to tie up a lift while they wait for something to arrive from a vendor far away. The front suspension on the truck is in fine shape, king pins are new. The front leaf springs have a downward arc, and hence the shackles are "collapsed", and the springs no longer do their job as intended. I've done all kinds of work on old trucks over the years, but I've never done a leaf spring replacement, so I don't know what it entails, just that it is unpleasant work. If there is a thread outlining the process, that would be a great help to me.

I've located replacement front leaf springs for my 1954 1/2 ton Dodge pickup. Are there other parts that will need to be replaced along with the springs, i.e, shackles or bushings ? I'm having a repair shop do the work, and I want them to have everything they'll need ahead of time. I chase the parts, and they do the work. Thanks.

I'd like to add something here. The function of the tubular spacer is to prevent the bolt from compressing the cushion. The engine is supposed to sit on the cushion, held by its own weight. The bolt just keeps it from hopping off the mount. If you compress the cushion with the bolt, you've lost the vibration insulating properties of the design.

Here's a very late response. The thing to keep in mind with these is the basic principle, which was not obvious. The purpose of the tubular spacer is to prevent the bolt from tightening down on the rubber cushions. The cab sits on the upper cushion by its weight, not by the bolt being tight. If you tighten the bolt onto the rubber cushion, you are back to transmitting the frame vibrations to the cab. The cab needs to float. In answer to your question, if you read the installation closely, you'll see that the height is adjusted with spacer washers if needed, not by adding cushions. As I recall, the driver's side mount has a cushion above and below the bracket, the idea being that the engine torque will work against the weight of the cab, and lift the cab up as well as the force of gravity pushing it down. Again, don't neglect the tubular spacer and its purpose. If you use the bolt to tighten the cab to the frame ( even if there's rubber in between), you lose the vibration insulating. Imagine the mounts this way. The cab just sits on the frame by gravity. The frame and engine vibrate, but the cab just sits loosely on top of a rubber cushion and receives little of that vibration. The bolts serve to keep the cab from lifting off the chassis when you hit a bump or go around a corner. Squeeze the rubber cushions with the bolts and none of that works.

The spring leaves are a little pitted and after 68 years may need a rest. Unless there is a compelling reason to keep them, such as new parts being low quality, I'd like to replace them.

Thanks. It doesn't appear that they offer my model and year, at least judging from the list on their website.

The front leaf springs on my 1954 Dodge 1/2 ton truck look tired. They no longer have an upward arc, and in fact, have a bit of a downward arc. There is only about 4" of clearance to the frame in the center of the spring. They consist of 7 rather narrow leaves. Is there a good source for replacements built to the original specifications ? I feel safer buying good replacements rather than having a spring shop make them up.

Here's my answer to my own question, as I see it. Without the vacuum advance, the total advance is only 9 degrees, as opposed to the 21 degree total advance on the 1/2 and 3/4 ton models. It seems an engineering choice designed to make the engine less spritely, but last forever. In my case, that's relevant because I found that retarding the spark significantly put less strain on the engine and made it quieter at higher rpm's. So today I did just that. I disconnected the vacuum advance, and set the initial timing at 2 degrees after TDC, as specified for the non-vacuum advance models. At 2600 rpm I now have only about 10 degrees of advance, which quiets the engine down considerably. I intend to rebuild the engine soon, but meanwhile I can run it with less strain by duplicating the set-up and spec's of the non-vacuum advance heavy duty trucks that were designed with longevity rather than speed in mind. This has been an education.

In looking over the specifications that Merle provided, I see that on the engines with vacuum advance, the ignition is advanced about 11 degrees at full vacuum (steady speed). The mechanical advance at higher rpm's is about 10 degrees, giving a total advance at steady, highway speed of 21 degrees. On models without vacuum advance, the numbers are very similar, except the total is 11 degrees, not 21, because there's no vacuum advance. Initial timing in the spec's call for retarding the spark 2 degrees on the non-vacuum advance models, making their total advance 9 degrees. So it would seem that with the same engine, at steady highway speed , on some trucks they run at 9 degrees total advance, and some 21 degrees total advance. Seems like quite a spread. Could someone explain the intent here ?

One final thought. The vacuum advance and the centrifugal advance seem to be working more or less properly, yet the truck engine runs much quieter at 40-50 mph if my initial timing is set at 8 degrees after TDC, which is quite retarded. Could it be that by retarding the timing I am simply masking the sound of a mechanically worn engine ? I have good oil pressure, decent compression, etc., but it's too noisy (clattering) at 40 mph and above unless I keep the spark retarded.

I set the timing using a vacuum gauge, adjusting it until I got the highest vacuum reading at idle speed (500 rpm). I rotated the distributor until I got a steady 20Hg on the gauge. That seemed to be about maximum. Then I checked the timing with a light. It was about 8 degrees before TDC, read from the crank pulley. At this setting, the engine idles fine but is very noisy above 40 mph. With the vacuum advance disconnected, at 2600 rpm, the centrifugal adds about what it should, 10-15 degrees. I'm doing some estimating because it's beyond the marks, but it seems in the ballpark. So with the timing set by the vacuum method, at about 8 degrees BTDC, the truck engine is very noisy above 40 mph. I verified that the centrifugal advance is working properly. I retarded the timing to 8 degrees after TDC, and it runs great, like a zippy old 6 cylinder, no problem at 50-55 mph. I suppose it's possible the vacuum advance could be advancing the timing way too much, but I doubt it's even mechanically capable of advancing it enough to create the situation I'm experiencing. Whatever the reason, 8 degrees after TDC seems to do the trick, with no ill side effects. I wish I knew why.

Thanks. My question is whether running the engine in the shop at 2600 rpm should cause the vacuum advance to be fully activated, assuming it is working properly and there are no vacuum leaks.

If I have the truck in the shop and rev it up to 2000 rpm, am I seeing the full effect of both the centrifugal and the vacuum advance when I am using the timing light ? I'm not sure if 2000 rpm and no load would be a maximum vacuum condition or not. Or should I be disconnecting the vacuum in order to isolate and test the centrifugal advance by itself ?

My timing light is an older, non-induction type. I'm open to suggestions for a good quality up-to-date replacement. An over-reacting centrifugal would possibly give me the effect I'm seeing. How much should the centrifugal mechanism advance the spark at 2000 rpm ? As I stated in my original post, If I set the timing to TDC at 400 rpm, it is advanced 10 degrees at 1500 rpm and at 2000 rpm it was well past the area with marks, far enough that I couldn't even estimate. Isn't there a mechanical limit to how far it could advance the spark, even with bad springs ? If it is indeed a problem with the centrifugal advance, I could pull the distributor and have it checked and repaired, or.... just compensate by retarding the spark the way I did before. Even with the spark retarded 10 degrees at 400 rpm, it idled just fine. Bad idea ?