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Thanks. These are shots from after doing some channel work and runner anti-reversion work right under the phenolic spacer. This is a 74 Nikki manifold and a 76 Hitachi spacer which required a bit of work to make it work. The thickness of the Hitachi spacer perfectly matches the length of the OEM studs in this manifold, which is why I chose to use it. It also has a nice factory channel connecting the primaries not unlike the modern SA and FB spacers have. And that is why I cut channels in the manifold as well, to more closely mimic the factory calibration of modern SA and FB carbs on SA and FB manifolds which have primary and secondary communication.
These engines just work better when you have channels and at least some form of anti-reversion effects in play (the factory spacers for these did have a smaller opening than the inlet of the manifold runners, but the hitachi holes are slightly further apart and needed some finesse work, plus the mani lacks channels because it is "old school"). The channels provide a much better vacuum signal to all three primary circuits: idle, transition and main. Not to mention the secondary transition seems to work over all better as well with mechanical secondaries (you can't run vac sec with hogged out venturis). I've channeled several Hitachi manifolds so I can run a Nikki on a 4 port 13B, but this was my first actual old school 12A mani channel-cutting job. I think I did well enough. Nice little anti-reversion lip all around. Much better than the pro-reversion lip it would have had in places, had I left it alone.
The shaft has been modded for boost (the right side was weld-filled and slotted for 12 degrees down from a stock of 20 degrees). This mod allows for higher power levels with boost. I also wiped out the old hard grease that was slow to respond and added some new red grease because red makes you go faster!
Here I'm trying to get a good balance of contrast on a white surface with black parts. These are some Camden SC parts. The o-rings fit their 7". One is used and the other is new. Betcha can't tell which is which... kidding. The dizzy on the right is the 12 degree boost prepped one featured above. All back together now and red-to-go.
11-24-19, 01:01 PM
