I just wanted to drop a note on my experiments with the self-made intake. During last winter, I reduced the size of the plenums by molding some epoxy on the plenum floor. This appears to be a change in the right direction, as it stopped popping in the exhaust at low rpm's, and idle isn't so shaky anymore. I also roughened the surface of the epoxy, to avoid fuel dropout. If you look at the plenum floor of any V-8 intake, you will see that the floor is heavily textured. The engine is still not very responsive to the throttle, and needs full accelerator pump shot from both carbs. I think I could yield further benefits from filling the plenums even more. My basic design "error" was the plenum design. The fact that one carb only feeds 4 cylinders now, slowing down the flow in the carb, makes it even worse. So, anyone who's going to build a multi-carb intake, would better avoid excessive plenum areas, and try to arrange a progressive setup, so that only one carb feeds all cylinders at idle, and other carbs step-in later.
For those who may not be familiar with my Buick site, here's the link: http://gamma.nic.fi/~marlin/Rmaster.htm

thank you for the link your car is , a beauty , seeing the photos makes me want to work on my car ,

Thanks for the update Jyrki. I've always found your site helpful and very inspirational. You're tackling the issues that are on my horizon. Please keep us updated in the future as well.

I've been watching this and contemplating also. Do you have any inside shots of the intake??

Unfortunately I don't have any good shots, but there will be one bad shot once I get my May diary finished in a couple of days

I think we should quit playing around with carbs and convert to port fuel injection.
I wonder what the lack of heat to the manifold does for drivability? My heat control stuck, so I closed it years ago. It doesn't get too cold here in winter, though.
Old-time mechanics tell me the Buicks had a tendancy to run 4 cylinders lean and 4 rich: I can't remember which is which, but it would tend to damage four of the cylinders 9the center four or the outer four) with too much heat if the carb wasn't right (or maybe if it was!).
Around here (the Southern US) the Straight-Eight Buick engine was considered by rural people to be the best engine to power a small sawmill, etc. on the farm. I suppose the large engine was the one they were interested in.
Regards to the Straight Eight crowd

I have run performance oriented v-8 with no heat riser and the heat ports to the intake blocked. The only disadvantage is when you start your car you may have to keep it running with the throttle for a minute or two before allowing your fast idle and choke to take over.

With the V8, you always get heat rising from the engine. With the straight 8, the carburetor sits away from the engine heat, just like the straight 6's and 4's. I had a problem with a VW (golf) in Ireland, that after much frustration turned out to be carb freeze up!! I pulled of the air cleaner one chilly morning to see a golf ball size piece of ice sitting on top of the carb, it melted in a second or 2. At any temp below 60deg it's possible to get ice inside the venturi's which makes your engine buck like a bronco. I found that a hot air tube was missing. Once I replaced, it the problem magically disappeared!! I highly recommend using something to warm the carb.

I tried filling up the plenums further with epoxy, and the engine seems to run a lot smoother. We just returned from a 300-mile trip, and the mileage averaged 18 mpg (= 13 L / 100 km), which is way better than these cars used to do, mostly beacause the 2.73 rear gear. We mostly cruised at 60-70 mph. I also tried it on the strip: ET 19,50 s / 71 mph trap speed. I could probably get it run high 18's with some training. Now I couldn't launch it properly off the line, and I was also afraid of letting it rev above 3500 rpm

What I have heard about the heat riser in the Buick STR-8, it gives nothing but trouble, especially on hot starts. I won't be driving in freezing temps, so I won't need one. My 1983 Caprice was missing the heat riser valve, and the venturis froze up when the temp was just slightly over or under freezing point, and the humidity was high.

Port injection won't do, because the intake ports are siamesed.

I've thought about running a length of steel tubing or 2 along the bottom of the intake and plumbing it inline with the heater.