Don't hate, but I sold my 510 for a bmw e30 and I'm looking to purge my l series parts. Here's a link to most of what I have on craigslist:
http://seattle.craigslist.org/see/pts/1056040457.html
Happy to answer any questions, 425 248 5814
Hey sorry to mix you up... but I just checked and the 4 bolt 46mm SUs from a roadster fit the two bolt l series intake manifold. So if its easier for you to find one of those manifolds than to fab a custom one, thats an option
I too was planning on running some roadster carbs for my l20 build. Way too far into the process, I realized the roadster u series manifolds have four bolts, while the l series manifolds have only two! In other words, theres no manifold that connects the 4 bolt sus to an l20b head without some custom work. Hope this was helpful!
I actually stole these carbs from my dad's U20 build (he wont be needing them for a while). At first I thought they were 240z carbs, but from what I understand they have too big of piston return springs to be 240z carbs. I know the U20 came with more than one type of carb option, but I think 46 mm SUs came stock on some 2000 roadsters.
I see what your saying about the cam timing being thrown off by the distance between the two timing sprockets; the chain tensioner would take up the slack on one side, causing the cam to rotate in respect to the crank. I wonder if I could modify the stationary chain guide on the right to take up more slack? This might cancel out the timing shift. Just thinking out loud