Multiple contours, many folds.

This post marks quite a moment in the progress of this multi-year endeavor. What started out with an electrical problem and ended up as a restoration project has finally passed the summit.  No more research. No more engineering. Now it's just putting shit back together. You might ask what the specific tipping point was, and if you did, this is my answer: cutting a hole.

See, as I mentioned in my last post, the manifold I'm using was designed for use with the Chrysler-engineered MPI system, and not for a carburetor, though the Weber kit I purchased included an adapter plate to fix on the riser for the Carter carburetor used by the 258.  Unfortunately, the plate's footprint doesn't match that of the throttle body used by the 242.  Not by a long shot.

First, I need to mark out the spacer, followed by the (striped) section needed to be cut out to allow unobstructed flow from the barrel ports.

And here's the moment of triumph:

The cut has been made.

From here it's a matter of brazing the plate to the manifold.  If I suck at brazing, it'll be JB Welding the plate to the manifold.  Afterwards, I'll be doing the same with 1/2" aluminum plugs in the MPI ports, and lastly, checking thread pitch for any metric-tapped holes and retapping them for standard fasteners (all hardware on the Gremlin is SAE, with the exception of the mounting bolts for the Saginaw steering pump and I intend to keep it that way for the sake of consistency and minimization of tools needed while on the road).

Now you may be asking why I would want to use this instead of the old manifold?

My main reason is because this iteration of the 242 manifold has equal-length runners, so it should provide a much more even distribution of fuel/air mixture to each cylinder than the older designs using runners of unequal length. Following this is the feeling that it wouldn't be worth the effort to retrofit the 258 intake, as there wouldn't be many benefits to doing so.

One thing the 258 manifold has in it's favor is the interior below the carb riser that is designed to keep the fuel from pooling in the bottom of the manifold in certain temperature ranges.  This is easily replicated in the new manifold, especially with the wider opening that's been cut.  Add to this the fact that the 258 manifold is cast iron (and heavy as a really heavy thing), is not as amenable to the installation of headers, and that it has the carb barrels oriented in a way that can add to the uneven fuel distribution issue I mentioned previously.  When all of this is accounted for, the little bit of work needed to modify this manifold provides a lot more benefit than the drawbacks that would accompany fitting the 258 manifold to the 242 head.

Of course, I could just use the other manifold, fuel rails, injectors, and so on that I have sitting on the shop floor and convert to a fuel injected setup, but if I wanted to dick around with computers right now, I would probably still be at my old job.


EDIT: for some reason, I think it's appropriate that this link be reposted.
https://www.youtube.com/watch?v=NQff4GpvM4w