Hi, I have just joined the forum today. I am wondering if I can get some advice on the following bit of MIG welding that I would like to do. I have MIG welded, on and off, since around 1973, but only on vehicle bodywork and welding up angle iron fames, and the like. I am no expert.
I am rebuilding a 1914 Humberette cyclecar which has a 1000cc water cooled V-twin engine. The engine uses an unusual, conrod set up. I would like to change the conrod set up to a fork and blade system so that I can use roller bearings on the big end rather than the phosphor bronze bearings in the conrods. I think that it may give the engine improved balance and less vibration. I have also replaced the cast iron pistons with more modern lighter Ford Zetec alloy pistons because the original pistons were cracked.
I have obtained two sets of World War 2 ‘old stock’ V-twin conrods for a 45 Harley Davidson engine. Below is a photo of both the Humber and Harley Davidson conrods.
The Harley Davidson (left) Humber (right)
Now here comes the problem. The Harley conrods are around 7.5” between centres and the Humber conrods are around 9.5” between centres. Therefore, I need to increase the rod length by approximately 2”. I think I have two options.
I can cut a section out of one set of rods Harley rods and weld it into the other set of Harley rods. Or, my preferred option would be to machine up a section of steel to match the section of the Harley conrod in my Bridgeport milling machine and MIG weld them into the cut rods. The rods would be cut at a diagonal of 45 degrees to increase the weld length and I would make a sturdy jig to hold the parts in place. Below is a drawing of the 'blade' Harley Davidson conrod I want to extend, the forked conrod is similar, but I have not drawn that one out yet.
If money was no object the obvious thing to do would be to have new conrods made. As good running examples of these Humberette’s only fetch between £10k and £15k, and I have spent more than this on the restoration to date, and still need to spend more, I don’t want to go down that expensive route of having new rods made. I also don’t have the machining skills necessary to make a complete set of fork and blade conrods myself from a steel billet. Some may ask why I am bothering messing about with this idea, or even restoring a car that won’t be worth the money and hours put into it. My reply is; doing the work gives me quite a lot of pleasure, it also gets me out of helping the wife with housework and gardening!
My question is if I buy ‘new steel’ to make the section that I would like to weld in, what specification of steel would be best for welding to the old Harley Davidson conrod material and does anybody have any tips that may help with the welding? Another question - does anybody know what material Harley Davidson would have used for the conrods during the WW2, or have a suggestion on who to ask?
This is a photo of the Humberette, partly dismantled, showing its engine.
If anybody is interested in following the restoration I am reporting it on the following AACA forum:
https://forums.aaca.org/topic/313496-reports-on-a-1914-humberette-restoration/
I am rebuilding a 1914 Humberette cyclecar which has a 1000cc water cooled V-twin engine. The engine uses an unusual, conrod set up. I would like to change the conrod set up to a fork and blade system so that I can use roller bearings on the big end rather than the phosphor bronze bearings in the conrods. I think that it may give the engine improved balance and less vibration. I have also replaced the cast iron pistons with more modern lighter Ford Zetec alloy pistons because the original pistons were cracked.
I have obtained two sets of World War 2 ‘old stock’ V-twin conrods for a 45 Harley Davidson engine. Below is a photo of both the Humber and Harley Davidson conrods.
The Harley Davidson (left) Humber (right)
Now here comes the problem. The Harley conrods are around 7.5” between centres and the Humber conrods are around 9.5” between centres. Therefore, I need to increase the rod length by approximately 2”. I think I have two options.
I can cut a section out of one set of rods Harley rods and weld it into the other set of Harley rods. Or, my preferred option would be to machine up a section of steel to match the section of the Harley conrod in my Bridgeport milling machine and MIG weld them into the cut rods. The rods would be cut at a diagonal of 45 degrees to increase the weld length and I would make a sturdy jig to hold the parts in place. Below is a drawing of the 'blade' Harley Davidson conrod I want to extend, the forked conrod is similar, but I have not drawn that one out yet.
If money was no object the obvious thing to do would be to have new conrods made. As good running examples of these Humberette’s only fetch between £10k and £15k, and I have spent more than this on the restoration to date, and still need to spend more, I don’t want to go down that expensive route of having new rods made. I also don’t have the machining skills necessary to make a complete set of fork and blade conrods myself from a steel billet. Some may ask why I am bothering messing about with this idea, or even restoring a car that won’t be worth the money and hours put into it. My reply is; doing the work gives me quite a lot of pleasure, it also gets me out of helping the wife with housework and gardening!
My question is if I buy ‘new steel’ to make the section that I would like to weld in, what specification of steel would be best for welding to the old Harley Davidson conrod material and does anybody have any tips that may help with the welding? Another question - does anybody know what material Harley Davidson would have used for the conrods during the WW2, or have a suggestion on who to ask?
This is a photo of the Humberette, partly dismantled, showing its engine.
If anybody is interested in following the restoration I am reporting it on the following AACA forum:
https://forums.aaca.org/topic/313496-reports-on-a-1914-humberette-restoration/