Tom Kendall wrote:
<SNIP>
Tom Kendall wrote:
Wow! Quite a response everybody. I just got into my e-mail to see what's
up and I find interest for 10 or so manifolds! As Paul has said, let's
check all the fit-ups, then we can go into production. I can answer a few
questions in the meantime though:
The "sockets" for the tubing bends were left rough as-cast as a cost saving
measure. Paul and I felt that it would be better to let each builder
die-grind to fit and seal with RTV or JB Weld. Since each builder's
configuration may be slightly different, boring "one size fit's all" sockets
may be a mistake.
Note that you will need to use a rotary burr and not a grindstone since
stones will clog up with the soft aluminum. If I can believe my dial
calipers, the rough sockets are 0.01" to 0.03" undersized, so it won't take
a lot of hogging to get a nice slip fit. A little more work with the
grinder and you can smooth the transition from tube ID to runner ID. If
there is interest I'll see what it will do to the cost to have these sockets
cleaned up by the machine shop.
There is plenty of meat on the casting to permit drilling & tapping...
probably enough right where the runners neck down from the sockets to the
nominal diameter to permit machining in a recess for injectors. But we
didn't plan for that configuration. If there is interest in this approach,
I could make a modification for some castings to have bosses for injectors
on each runner, but that will have to wait until the first run is done and
out the door. Note that if you have a turbo, there really isn't much room
for a row of injectors and a fuel rail right on the manifold. Not too safe
either since the turbo runs very hot.
I will check on the alloy being used to make sure that the production
manifolds can be welded readily. There are several alloys available, and
some can be welded while others can't. I suspect there may be a few out
there who will want to seal weld their tubes in place, put on brackets for
other attachments, etc.
Chrissi asked about port match-up: As best as I can tell (since I don't
have a 12B sitting in the garage), the manifold ports are at least a large
as the ports on the assembled engine and match up very well
center-to-center. The web between the two inside ports is very thin, and
appears to be thinner than the web in the intermediate housing (judging from
the housing on my 20B). Because the as-cast surface of the manifold is
fairly rough, I believe that something like JB weld would work adhere just
fine if you want to fine-tune the manifold to exactly match your engine's
ports. Smear some Prussian Blue on either the manifold or engine mating
surfaces, bolt up, and remove. The resulting "blue print" will give you a
real good map of what needs to be removed and what you may want to add back.
>From the photos you can see that you will need some longer M8 bolts for at
least two (maybe three) of the holes than what is used on the stock
manifold. Due to the routing to get all 4 runners lined up over the top of
the engine, two of the bolts holes had to be extended up through bosses
right along the runner walls. Of course the center bolt on the stock
manifold was longer to start with.
And you can rest easy Jerry. As long as there is demand, we can crank out
more manifolds. I've got the pattern and any decent foundry can pour the
metal at a constant per-unit price. It won't be worth it to make batches of
less than a half dozen or so though because of the machine shop setup costs.
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