Re: [Chrysler300] Motor

[Gary Nelson <Gary@xxxx>]

My opinion:
I would think twice about boring a motor more than .060" over. Most 
standard pistons are only offered .030" to .060" over.
When I had my 392 short block rebuilt by Dick Landy's shop it had already 
been bored to .060" over. They would not bore it and honed it to .065" over 
and made custom pistons for .065" over.
As far as using torque plates. They are used when power honing not boring. 
I asked if they were going to use torque plates when honing my engine. They 
told me for a street application your wasting your money. Torque plates 
will give you as near perfect ring seal as you will get, but only needed in 
a race application when you must have the most power the engine will put 
out. At Landy's prices I am sure they would have been glade to put it on my 
invoice if they thought it should have been done.
A good power hone cross hatch with molly rings will do a fine job for any 
street motor.
Always use a good reputable machine shop with known qualified personnel. 
Boring, honing, decking, surfacing, align honing, rod rebuilding and 
balancing are all very precision operations. Most tolerances are held to 
1/2 of one thousandths of an inch. A slam bang re builder will produce a 
lower performing motor with a shortened life.

Gary, The Parts Doc





At 10:38 AM 5/23/02, Ryan Hill wrote:
> With regards to the machining of the block, you should be able to take that
> block to at least 70 or 80 thousands overbore but I'm not sure what you will
> require? In any case it is good practice to use a torque plate when doing
> the boring.....especially when you are reducing the wall thickness
> dramatically. Also, when assembling the short-block be sure and use a rope
> seal around the rear crank journal(rear seal). They last much longer than
> the cheap seals provided in most gasket kits.
>
> As for the heads, if you have access to a die grinder you can port match the
> intake to the head very easily and improve the flow quite a bit. Here's a
> trick:
>
> When you remove the intake from the head, remove the valley pan and clean
> off the pan and the head mating surfaces. Lay the valley pan back in place
> and bolt it down if needed to center it. Inside the openings on the pan you
> will likely see quite a bit of head material that doesn't match the port
> pattern of the gasket.......spray some grey primer,white paint, etc. at the
> gasket on all the ports. When you remove the gasket you will have a perfect
> pattern painted around each port. With a die grinder, remove the material
> that is painted to give you a perfect "port match". Be carefull to grind at
> a 90 degree(+/-) angle from the machined surface and don't damage the mating
> surface.
>
> In addition to removing the excess material from the lip of the port you
> should also smooth out any slag or burrs inside the runner that may cause
> extreme turbulence. Do not smooth out the runners too much as there should
> be some roughness to the runners to properly mix the Air/Fuel as it heads to
> the cylinders.
>
> Repeat the process with the same gasket to the intake manifold and you will
> improve the flow and equalize the volumes being delivered to the combustion
> chambers. This can also be done with the exhaust side. There are some power
> gains to be had here but at the very least the engine will run smoother.
>
> If the engine has been machined before, check the deck height and be
> carefull about removing any more material from the block or head. You could
> end up increasing your compression ratio, having a problem mating the intake
> to the head, and in extreme cases cause rocker arm failure(even with
> hydraulic lifters). This problem can easily be solved with thicker head
> gaskets but it's always better to know before you assemble the engine.
>
> Remember also that with any cam change and flow changes that your carb
> should be adjusted or modified to allow for the new demands.
>
> Hope this helps. Ryan
>
>
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