OP , thanks for the explanation .much good info but like nm9s said there is a big piece missing for us mopar folks useing certain factory heads. 1968+ big block, many 318, all 340 and early 360 heads have a fully round open chamber with a recessed area where we want quench. I measured this recess on a 340 head at .090". so a copied chevy small block article that states "quench is nothing more than the piston in the hole depth plus the head gasket thickness" is lacking for many mopar engines. for engines with fully round open chambers quench is the piston in the hole depth plus head gasket thickness plus head recess
BTW, the KB243 pistons have a step up on the piston that can be used to fill that gap to some degree. You will still have to do some decking or head shaving (about the thickness of the head gasket or a bit more) to get it down to a usable quench gap with the open head.much good info but like nm9s said there is a big piece missing for us mopar folks useing certain factory heads. 1968+ big block, many 318, all 340 and early 360 heads have a fully round open chamber with a recessed area where we want quench. I measured this recess on a 340 head at .090". so a copied chevy small block article that states "quench is nothing more than the piston in the hole depth plus the head gasket thickness" is lacking for many mopar engines. for engines with fully round open chambers quench is the piston in the hole depth plus head gasket thickness plus head recess
First, no hemi is a "hemi", but gens I&II are as close as you'll getThis all makes sense to me as well.... The Stage 3 Hemis aren't true "Hemi" for this very reason, the stage 1 & 2 Hemi had NO Quench area, BUT still ran like Hell like as tho the driver stole the car they were in.... so, the quench area, is just a "boost" to Wedge type motors? For complete A/F combustion?
Seems to me that the Mileage this would create and complete combustion is about the only gains, and that ought to produce a little in the HP range of things but......Is this why the Wedge motors in the 60's were almost max'ed out in HP? I mean, yeah besides larger CID per cylinder.
I clicked agree
actually squish helps on the early Hemis and 4v OHC motors
on the early hemi we got it by using a larger bore against the early head (which has raised ports in any case compared to the 392
you can do the same thing with the late hemi
you can also run the dome next to the combustion chamber on the side away from the plug
if running big valves you have to radius the top of the block where the intake is flow does not like to hit sharp top of block and neither does the valve
and BBM is about the worst post 1967 915 head
even there the plug and valve location is about as bad as you can get
the 361-413 Truck motor used spark plugs in the 1958 Ford FE locations (same locations later used by the LA engine) so Chrysler did understand the problem- and makes them much easier to change (still not so good chamber but about same as most at
BBM introduction in 58)
so why not in the BBM?
our loss
oops did not notice date on this thread- still good
Good info is never too late !
So 361/413 truck heads would work well for a torque motor ? Were they closed chambered ?
I have a near identical 5.9 build right now and am finding it too wants a ton of fuel ! So much that my bumper has fuel on it. Yet the plugs are tan.
As for the 413 heads... they might be a great way to build a motorhome engine with a little higher compression. Weight would not make a difference in that application.
I understood white to be lean. Tan to be normal and black rich ...
It is said that todays fuel makes it harder to read plugs.