Gidday.First post so thanks in advance.Question for the doc.I have an Hpack with the defects as described in a previous post ie;dividing walls between the individual runners end at plenum with a < shape.I'm in New Zealand so sending the manifold back to clifford would be pretty expensive because of the freight charges.Is it possible to post pictures on the /6 website of the plenum of a good Hpack so i can see what it's meant to look like.Maybe a measurement from flange to plenum of the length of each runner dividing wall if poss.I think i'm stuck with having to try and fix it.(used to be a fitter & turner in a past life).Great website folks!!
Cheers.

The Hpak dividers in mine are the < type and that should be normal for 'flow', the problems others are having are: carb mounting stud holes are 'off', cavities in the runner walls, casting flash in hard to grind out areas, plenum irregularities(casting problems).

Here's a look down the throat of my recently 'divided' plenum, and you can see my runners are the same < type....(if yours look rough or broken, then it's a clifford problem).




-D.Idiot

The un-even runner divider ends are not that big of a problem, the casting flash and mis-drilled holes are a bigger problem.

The main issue with the < shape at the ends of the runners is that it slightly changes the flow and plenum size, basicly the engine sees the runners as a little shorter and the plenum as being a little bigger. (this is better for higher RPMs)
That is not a big issue but I worry that the fuel distribution may have changed in some way.
If you already have the manifold, do a deburring "clean-up" job and a trial fit-up, then just run it and dial-in the distribution from there.
DD

Doc, it's a shame to hear about all the problems Clifford's having with the casting. It's such a simple thing for a manufacturer to do a little inspection... Seems lately Clifford Performance is in decline. I remember working with them on a Chevy 6cyl setup. They were very helpful then; but, that was years ago.

The Hyperpack repro manifolds are your design, right? Obviously you chose not to "mass produce" them yourself. Do you think Offenhauser would be interested? Have you considered approaching them or are you limited by some contractual agreement with Clifford?

Just a thought. I hate to see a good product be destroyed by an incompetent manufacturer.

_________________
My truck is a Frankenstein creation
Built from the dead carcasses of others
And brought BACK TO LIFE!

The "bottomline" is that Jack Clifford was the engineering "brains" behind Clifford and now that Jack has passed-on, I feel there is no one at Clifford to figure-out the technical problems.

As for the H.-Pak being my design, truth is that I reproduced Chrysler's design and did additional testing and made changes to handle higher flow and improve fuel distribution. What this really means is that I built and refined a new set of sand casting patterns needed to make these manifolds. It is the casting patterns I created that when to Jack Clifford a number of years back (1998) and a set of "how to" instructions for the casting and machining of the manifolds. Looks like Clifford still has the casting patterns but lost the instructions on how to cast and machine them.


Getting the patterns back would be the key to getting someone else like Offy involved with making these. Another option is for me to work directly with Clifford's foundry when they cast the next group of H.-Pak manifolds but that offer has fallen on "deaf ears" over at Clifford. If they told me when the sand cores were ready and paid for my travel, I would hand prep. each sand core before they were cast into manifolds.
(The sand core is used to make the hollow runners and plenum areas so when you "hand finish" a manifold's sand core it is like doing "porting" but a lot easer because you file on a soft sand "positive", instead of grinding inside hard metal passageways. As an example, the "<" at the ends of the runners take about 30 seconds each to "square-up" on a sand core, you just file out the extra sand.)
There is a photo of H.-Pak sand cores all preped and ready to be cast in the lower left corner of this photo page:
DD
http://www.dutra.org/pictures/engine/pa ... roject.jpg

The pattern was fixed before I left. Ronnie at the pattern shop had fixed all the inside problems and even furnished a fiberglass mold of the inside. I do not know if they lost that inside mold or what in their move. QC on "flash" is a simple thing to take care of before boxing the manifold up for sale. As for the hole pattern(s) maybe it would better if they just made a pattern to accept their two or four barrel plates or just left it up to the customer to drill their own carb pattern. There were too many holes for too many carb options in my opinion.

Good luck Doc on getting that pattern back. If you do and need someone to talk to Tay or Vince at Offy for you let me know.

_________________
Philip Cook
Perma-Cool
400 S. Rockefeller Ave
Ontario, CA 91761
(909) 390-1550 Phn
(909) 390-1551 Fax

It takes a good set of patterns and someone who is detailed oriented
to do low volume quality castings. You ought to get predictable results
in each casting run if you are careful and pay attention, take your time. I am looking for a local hobby casting network where I live. I have been told by others who do this as a hobby that if you put in the effort and follow procedures you get good results *most* of the time.

I've also been told that there is no money is casting small jobs -- too much work involved. It's likely that Clifford is cutting corners because they don't have the volume to make the project pay its way.