What are "quench heads"

Fordota · 06-24-2007, 08:45 PM

I been reading about heads and stuff. I keep hearing "quench heads" being referenced. Does anyone know what they are?

dbu8554 · 06-24-2007, 09:16 PM

duh they quench your thirst for more power lol jk I think it has to do with the shape of the combustion chamber and the size but i am not 100% sure on that

frdnut · 06-24-2007, 09:27 PM

I have usually heard that term used to describe 351 cleveland heads which basically had two different style heads for the same engine...The 4V heads had smaller combustion chambers for more compression and better "quench"..The 2 barrel heads had much larger combustion chambers for low compression..

dbu8554 · 06-24-2007, 09:32 PM

well when talking about 351c you will most likley hear quench when comparing the closed chamber 4v heads vs. the open chamber 4v heads in that sense most people i know dont really talk about CC 4v heads and OC 2v heads and for the record ford did make CC 2v heads and they are the aussie 351c heads

ckelly · 06-24-2007, 09:55 PM

From another magazine article
"For decades, sharp engine builders have known about “quench” or “squish.” These terms refer to the area in a wedge-shaped chamber designed to create turbulence in the chamber as the piston approaches top dead center (TDC). This squish effect can also occur in other types of chambers as well. The basic facts relate to all wedge-shaped combustion chambers."

Motorhead · 06-24-2007, 09:56 PM

The 'quench' area of the cylinder head is the part of the head that is inside the cylinder but not part of the combustion chamber, meaning it is the same level as the bottom surface of the cylinder head. Ideally, when your pistons are set up such that they have zero deck clearance (the cylinder comes up dead even with the deck of the block), the head gasket will create a very tight .040 clearance between this 'quench' area and the piston, cooling the piston (where the term 'quench' came from) and also creating high velocity airflow towards the combustion chamber as it is squished out of the quench area.

A quench head is also referred to a closed-chamber head. The opposite of this would be an open-chamber head, which is one where the entire cylinder area is dished into the head as part of the combustion chamber. This has two drawbacks, as it does not have the cooling effect and high velocity airflow affect that closed-chamber/quench heads have, making them more prone to detonation, and also requires pop-up, dome top pistons to get an acceptable compression ratio.

The easiest way to tell a quench/closed chamber head from an open chamber head is to look at the shape of the combustion chamber (the dished in part of the head surface). If it is perfectly round, you have an open chamber head. If it is 'D' shaped or heart shaped or any other shape that creates a 'quench' area, then it is a closed-chamber head. Some heads, like the larger chamber 460 heads, have a pretty small quench area, and a large combustion chamber... but are still considered quench heads, although not as good of a quench as most small block ford heads.

xdclevo · 06-25-2007, 12:58 AM

Quote:

Originally Posted by dbu8554

and for the record ford did make CC 2v heads and they are the aussie 351c heads

All 351 aussie clevelands with 2V heads, only had open chambers.
All 302 clevelands had the closed or quench heads.
Here in Australia, they are just referred to as "302" heads.
Only reason is the 302c would have has crap compression with open chamber heads, so they made some to suit.

dbu8554 · 06-25-2007, 02:05 AM

oh dang dude i had no idea i thought all aussie 2v heads were closed chamber thanks for the info man

BrianS · 06-25-2007, 02:09 AM

"Only reason is the 302c would have has crap compression with open chamber heads, so they made some to suit."

That's why I don't recommend Bogus Boss 302s with OC Cleveland 2V heads. You'd be lucky to get over 8:1 with a zero deck, flat top piston.
A pop up piston might get you to 9.5:1 with poor flame travel and a somewhat aggressive cam would be needed to run on pump gas.

Mikes66 · 06-25-2007, 03:05 AM

1969 351W Hi-Compression Quencher heads. Hand ported with "D" Shape ports. "D" Shape was the fad of the day for Ford Exhaust Ports 25 years ago.

Fordota · 06-25-2007, 11:51 AM

Thanks guys, So is the term Quench Heads the same as Closed Chambers and just not reffered to as that as much?

So pretty much all of you then run Quench Heads and that is what I should look for?

Are the aftermarket badd@ss heads then Quench as well?