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Centerline double softmount for Weber carbs, any experience?

3K views 11 replies 7 participants last post by  Gordon Raymond 
#1 ·
Has anyone had any experience with the Centerling double softmount for dual Webers? It seems good in theory, stiffening the inner bores, tying the carbs etc, etc. The idea is to use single mounts on the outside bores and a double in the center. Any ideas out there? Is it a gimmick? Seems there might be good science behind it.
 

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#3 · (Edited)
I have used them for years with no problems.

101/105guy said:
The one I bought is a lot thicker than the single mounts
I measured the relative thicknesses once and found that I needed to stack two paper gaskets on the two outer single mounts to achieve the same dimension as the siamese inner mount. I wouldn't call that "a lot thicker". Even if I hadn't used the double gaskets, I'm confident that the rubber would have expanded/contracted enough to create a tight fit at the flanges.
 
#4 · (Edited)
The double mount is a preferred mounting method as it eliminates some balance link wear. It was used by Alfa on some Euro variations, but can be used with older US imported cars IF originality is not a concern. I use this center mount on all race engines using 40DCOE's. It works well.
There are some variations in lengths of the individual rubber insulators / isolators that have been available in the past. I have not checked length variation in new Pirelli insulator / isolators in either 40 or 45 mm sizes, nor have I compared the latest Pirelli offerings to old Pirelli supplied to Alfa years ago.
It is important that insulator / isolators be approximately the same length to avoid stressing Weber bodies. This would include the double center rubber. In the past, some of the individual I/I units were so poorly made that steel insert plates at either end were not even flat. One needed to remove studs and mill file the steel inserts flat, then make 4 the same length before reinstalling studs.
Many years ago, the only gaskets supplied were thin yellow gasket paper and these worked fine with original, matched length, old style Pirelli I/I units. Thicker greyish black gaskets are now commonly supplied. The thin yellow were sealed to manifold I/I, and I/I to Weber with "Gasketcinch" sealant with no issues. The thicker greyish black sandwiched between NON-FLAT I/I's will oftern burn through and leak air. A bad situation. If the I/I steel plates are flat, close to the same length, they will work fine with the thicker gaskets, but some gasket sealant should be used. I have had no problems using the double center I/I and close to the same length front and rear I/I assemblies, sometimes mixing thick and thin gaskets to get everything matched up to length, then using a sealant to be sure there are no leaks over time.
Below are pictured 4, tired 45 mm used yellow paper gaskets. The thin ones.
 

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#6 ·
THIN your center mount. I have used a mill to do this one or twice. Mine fit.
 
#7 ·
I don't know the process but I've got to believe that these should be machined square and flat after vulcanizing. There is no way that you could maintain tolerances otherwise. Actually, they should be molded, machined and sold in sets. Different molding times and temps will result in different expansion and contraction rates.

I'm sure the original Pirelli units were made right but I don't trust anything from aftermarket suppliers (speaking as an aftermarket supplier of molded rubber parts for the last 50 years).
 
#11 ·
Do other siamesed mounts work better than the Centerline ones? Perhaps ones from Alfaholics or Classic Alfa? These seem like a good way to go. I'm looking for the best mounting solution, but not finding much info on it.

Will
 
#12 ·
All I've used vary a bit. A few years ago there were some 40 mm singles that were horrid. The steel was not even flat, it appeared stamped, and the rubber did not last long. I pulled studs from these, and machined the steel flat and parallel, making them all the same length, only to watch the rubber deteriorate quickly.
The double mounts I've used have good steel inserts and both steel plates are parallel. Most are dimensionally very similar, though I've no idea where they were made. Generally, if you had enough singles, you could probably find two that matched the thickness of the double mount. I do not know, but guess the double mount manufacturer(s) do not make matching singles.
One of my customers recently sent me 4, 40 mm singles that had "Pirelli" cast into the rubber like those from years ago. They were new, and all 4 were the same length. I don't know where they came from, but if they really were Pirelli made, they might hold up like the Pirelli insulator / isolators from 40 years ago. I wondered at the time if there is a Pirelli made or marked double, and if so, would it match the Pirelli singles? I do not know.
 
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