<VV> new heads, VirtualVairs Digest, Vol 54, Issue 53

Tue Jul 14 10:44:45 EDT 2009

 Good input, thanks.

I think one of the issues here is we're making a LOT of assumptions in a vacuum. 

Individual heads have their advantages, but not significant over a three up design. 

I am pushing for the three up design to minimize the amount of design, fabrication, and engineering on pieces that have nothing to do with making power and/or improving cooling. 

The warpage issue is a guess. My assumption that a bolt on will increase market share is also a guess. 

The first one I was trying to address by copying the non power and cooling related aspects of the stock head as much as possible, including the milling cuts between the cylinders. 

The second one is a much tougher nut to crack. Your comment about having a bolt on head with significantly higher reliability is a GREAT one, I've had 140 heads drop seats before, and the cost of the damage goes WAY beyond the cost of the heads. Improved cooling would also make these attractive to the turbo guys, the airvair guys, the FC guys, etc., so, my thinking was there's a market far larger than just the hotrod guys. Of course, building in the ability to turn these into IR heads would satisfy these guys as well. Adding injector bosses would also be a plus, and that will need some serious thought as to where, which way to point them, etc. 

Don't worry about the CNC mill approach, that's easier than you think. Generally, for castings, all you need is a way to locate and attach the head firmly in the fixture. Well, these heads have two square ends, so, again, no big deal. Once done, it's a two setup approach, if there's a 5 axis machining center available. One for the valve side, one for the rocker side. And this capability is VERY affordable these days, once you get the first one made. And NO WAY would you want to make 100 of these manually! 
So, again, don't assume mills cost more per hour than a lathe, especially considering what we're trying to do here. 

The action items for this piece is, FIND OUT!! 

JVHR

-----Original Message-----
From: deltainc <deltainc at grm.net>
To: vv <virtualvairs at corvair.org>
Sent: Tue, Jul 14, 2009 9:15 am
Subject: Re: <VV> new heads, VirtualVairs Digest, Vol 54, Issue 53

----- Original Message ----- 
From: "Alan Roehrich" <idoxlr8 at earthlink.net>

Subject: Re: <VV> new heads, VirtualVairs Digest, Vol 54, Issue 53

>
> I looked into the prospect of making heads. I talked to three casting 
> companies, and three shops capable of machining the castings. It is easier 
> and cheaper to cast the heads without an integral intake.
>
> No one is likely to buy a set of heads and put 1 carburetor on each head. 
> Some people MIGHT buy a set of heads and put 2 carburetors on each head. 
> Odds are people buying heads will either run Webers/Zeniths, IR fuel 
> injection, or some form of common plenum setup. We looked at casting the 
> heads with a nice intake flange only. Then casting a plenum for the two 
> carburetors for a 140, a IR manifold for the Weber/Zenith setup, that 
> could also be used to make an IR fuel injection manifold, and a blank 
> plenum that could be modified. All six companies felt that was the way to 
> go.
>
> The ports and the chamber were thoroughly revised and modernized. We also 
> were looking at casting in bosses to mount a shaft rocker setup, we felt 
> there were pieces already available that could be used. I even had a 
> company lined up to make valves.
>
> Considering the probable market volume, we figured a set of really good 
> heads would cost close to $3K, at best, because there just wasn't going to 
> be any real volume.
>
> There was even a group like fastvairs formed for the head project, but I 
> killed it off because there was practically zero interest in actually 
> carrying through the project.
*********
Hi ... did you get into any discussion on warpage, either on castings, or 
billet machined heads.

I have thought that perhaps a great advantage of the 6 individual " pot " 
heads, or button heads, might be a minimum warpage problem.  Warpage could 
be disastrous financially for a small run of head sets, if the one piece 
castings warped about 1/8 inch at each end.

Another advantage of button heads in competition could be more readily 
repair of just 1 or 2 cylinders.

Another advantage of button heads ( or in fact even machining the 1-piece 
slab heads from bar ... ) ....   it is a lot easier to change a program than 
to make a new mold, which requires machining anyway .....  and I would 
expect about 8 iterations of a new head before turning out a version that * 
WOULD * appeal to a larger market.

I am not so sure that a $3000 price tag would be too much for a truly * WOW 
* set of heads .....  I do know that dropping valve seats, on an engine that 
you just overhauled at $3K for regular parts and labor .... might be worth 
an extra $2000 or so, depending on how far you are from home... (g)...

I like to compare how much to spend on a corvair compared to buying a nice 
used NEON, which is a neat zippy little car, but doesn[t rate a 2nd look 
from a pretty girl ....

Oh, the button heads might be able to be run on a large cnc lathe, that 
could make the actual production much cheaper, as opposed to needing a large 
cnc Milling center for the 1 piece heads, either to clean up castings, or 
machined from bar.

The big advantage with the lathe is that with bar feed, you have something 
to hold the part you are making.  With a mill approach, there is a large 
expense ( and headache ) in trying to figure out how to hold that funny 
shaped part.

********
In our toy car business, we have run thousands of button heads for the 
little engines, mostly all hemi-heads, with  various double bubble, tapered, 
low compression, high squish ... just a minute or so changing programs for 
different test heads.

*********
I think a good setup for the new heads would be 3 injectors per side, with a 
central mounted air throttle, or 6 Mikuni s, with hydraulic or pnuematic 
linkages on the throttle bodies.

just some thoughts, ken campbell, deltawerkes 

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