low-comp pistons was 413 motorhome/truck block

[John Meyer <donkiyoti@xxxxxxxxxxxxx>]

On Thursday, Jul 15, 2004, at 11:10 US/Pacific, William Parker wrote:

>  I don't know exactly your answers, but the replacement
> pistons for this motor, such as Silvolite #1272D, are deep
> dished and rated at  7.5(!) to 1 nominal static compression
> ratio.  I've heard that the heads have additional water
> passages, which I don't see would be of any harm in your
> Imperial, but you may need some early closed-chamber heads
> to get any decent compression.

This is interesting to me because my 413 was rebuilt with (I think) 
these pistons AND bored .060 over. It runs well and has OK power but I 
know it should be snappier especially at highway speed. Your answer 
suggests that I might be happier if I replaced the heads. From what 
years/engines do these closed-chamber heads come from? How much benefit 
would that provide in terms of compression?

In the meantime, I have purchased a set of flat-top, 10.0 to 1 .030 
pistons to use eventually in a new motor. I would either have to obtain 
a different block or have mine sleeved. Any thoughts on using sleeves?

Regards,
John Meyer
'65 Crown
Tucson