[AMC-list] 360 pistons

["Bruce Hevner" <scramblr@xxxxxxxxxxx>]

>I agree, hyper pistons are more affordable than forged but?I think the
problem is, there are so many cast versions out there for the 360 that the
market probably wouldn't warrant a mid grade piston for AMC.? One reason I>
say that is?I don't think there is the same benefits in regards to?skirt
gulling in an?AMC block as there is?in lets say a?Chevy engine.??SBC
engines?were prone to excessive cylinder wear and would regularly need to be
>bored even in low mile engines.? One know benefit of our blocks over
Chevy's is the high nickel content.? Unless an engine was rebuilt with
improper piston?to wall clearance, they typically wear well in this area.?
The >longer skirt type pistons did have a tendency to break in the skirt
area?but most have gone to a shorter skirt in recent years.? I doubt the
majority of users would see an issue with cylinder wear?especially in?cars
that >don't see the kind of mileage they did new.? I have taken apart lower
compression AMC blocks with 100K on them that had?very little wear and a lot
of times could either just be honed or go .010 over to clean up.? When >you
consider this, most applications were a hypereutectic piston would be a fine
choice, a cast piston would most likely also fit the bill.? This is a hard
call for a lower compression engine.

 

I don?t believe your right here (and this is just MY OPINION) but I think a
LOT of folks rebuilding AMC would be agreeable to an ?upgrade? in piston
quality. IF it didn?t cost too much. In the case of Chebbys a Hyper piston
only cost?s about $30 more than stock cast. And don?t get me wrong I am in
complete agreement that forged pistons ARE the best. BUT that being said
their cost makes them prohibitive for MOST street rebuilds and they are
really NOT necessary for most. I think if a Hyper piston could come in less
than $100 over stock cast they would sell. I know I could sell several sets
right now if they were available.

 

MY idea would be a D-shape dish (to match the combustion chamber), ZERO deck
9-1 piston with thinner rings. That way you wouldn?t need to chop the deck
so much to get decent compression as you do with the replacement destroked
pistons available now (do you know that replacement pistons are .020 SHORTER
than OE??) that makes your rebuild ?about? ¼ point LOWER in compression than
the OE piston UNLESS you deck the block. Is ANYBODY out there listening??
That would only need a rework of the finishing, the stock mold should work.
A configuration like that would be IDEAL for MOST STREET motors!!!!!

 

 

I can?get with?my piston supplier to see if there are any alternative for
this but my fear?is like with a lot of items?people say they would buy if
they were available, the activity over cast would not be there to warrant
the investment.??

What investment?? If a manuf is already making AMC stock cast pistons they
already have the mold which is the expensive part. The Silvolite rep told me
they would NOT NEED a different mold. Let me know what you find out but I
have had NO luck with the leads I have.

 

Like I said in my previous post, I feel most guys?are looking for that low
end?grunt torque out of their 360 and smaller engines.? That grunt power
really comes from higher cylinder pressures which is the real weak point of
cast and hyper?pistons.? They tend to?break when you have more heat/higher
compression or cylinder pressure even at rpms below 6 grand.

 

WHAT ??? Cylinder pressure (on a NA engine) is a result of static
compression ratio and intake cam timing. If what you are saying here WERE
true why would the OE?s use Hyper pistons on MOST Turbo motors?? No I ain?t
buyin,,, I have built quite a few Turbo motors using STOCK CAST HYPER
pistons and had no problems. They are a GREAT alternative upgrade to stock
cast WHEN USED AS INTENDED which is moderate street performance and even
competition. I have been using Hyper pistons for over 20 years,,, I LIKE em.

 

One other thing with KB pistons.? They use a Chevy pin diameter in the 401
pistons they make.? This meant you had to bush your rods for that size which
brought the cost?up a fair amount.? With that,?the?difference is not as
big?in price and makes you wonder if it is worth it verses forged.

 

That?s only for the 390/401 deal which I AGREE is a STUPID thing for KB to
have done.

 

I?htink you have some good arguments for them and might be better to see if
one of the cast piston makers would be willing to change their?fomula for
the pistons they already make to a higher silicone content type piston.

 

That?s what I suggested Silvolite do!!! DAMN If I had the Money I?D have em
made!!!

But HEY,,, that?s just ME!!!

Bruce Hevner

 

 

 

 

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