Recently been working to collect the proper parts for a triple Weber arrangement for this car. Many many thanks to
@Stevehose who has been super helpful in sorting out the options and directing me to sources for various critical parts. I have a bit of a journey ahead before I get to experience the music of these carbs personally, but I totally get the idea, and from a technical/performance perspective it seems like the next best thing to ITB injection, but for this car that would be a step too far. I am hoping to do this with an M90 engine, but if not I'll warm up the original old 3.0 M30.(I'll probably rebuild that engine anyway just so the matching numbers engine is available for some future collector - and I enjoy building engines!).
I recently purchased the Pierce manifolds for the Weber 40 DCOE carbs, I understand that this setup requires modification of the thermostat. I have to say I am pretty disappointed in the overall quality of these parts. They are very rough inside and out. Basically minimally finished mill quality parts. To use them will require surfacing the flanges (critical for good vacuum sealing, and extensive internal porting). Very much a DIY product... I can understand the lack of porting, as that's dependent on the specific application, but providing what is basically a sand cast finish on the flange mating surfaces seems pretty cheap, and the rest of the external finish s pretty rough.
At any rate, having been introduced to Tim Jason, a fabricator, I think I am going to just design my own intake manifolds, and work with Tim to get them made, and use one of his beautiful 3x Weber air filters and Weber elbow trumpets)
A couple of initial observations. I looked at photos of the VGS manifold. This is a single long unit that has six different intake runners. Seems like an easy recipe for tolerance buildup, where small errors in position compound, so the manifold is aligned well at one end and doesn't line up well at the other. From that perspective the Pierce units are better designed, since they only span two intake ports. That means they are probably less prone to fit issues as well as cracking over time (although I have no evidence that this has ever been an issue with single piece manifolds).
The M30 engine block is rotated 30 degrees from vertical. The Pierce manifold flanges are angled at about 18 degrees from inlet to outlet. This means the carbs will sit at a 12 degree angle. Not sure if that is ideal. I suspect that this is a compromise to allow clearance for the carb inlet trumpets, which will tend to interfere with the inner fender, more so the more the carbs are level...
I plan to do some measurements, and see how/if I can both avoid interference with the brake booster and the thermostat housing while providing room for some elbow trumpets into one of Tim's triple carb air cleaners.
First step is to get some measurements off the car, and then get conversant with a 3D modeling package, and maybe make some 3D models of manifold parts to then have cast and finished.
I'll keep y'all posted.
