440 build

[wyrmrider]

let's get clear
you can make great hp with an open chamber head as long as you keep the rpm above the torque (BMEP) peak
example: some stock classes
what sucks is on the street performance
I just do/did not build open chamber builds- go elsewhere except trailered cars
but then I do not run summit cams except for sale to used car dealers- but it is a better choice than a stock cam
never had a problem with valve bounce but I use asymmetrical lobes with carefully controlled close and the proper springs
The templets were for the earlier heads so BVVC with452 and similar- they work best with 902 and 915
now if you are building with a .050 down the hole and open chamber you have to back off on the compression and timing
problem is when you go to a thicker gasket and lower the compression you end up with the "use more throttle and make more heat" syndrome
so the temptation is to lower the compression even more
exactly what MOPAR did from 69> 73
Did not work then and does not work well now
but if you are on a tight budget you have to do what you have to do
Hints
minimize overlap and do not open the exhaust early- keep the valves on the seats as much as possible to keep the valves cool
do not lug the engine, keep it revved up when on the gas
no hot spots with open chamber???
The Plug is way down on one side and the other side is a long way off- the whole far side of the chamber is a hot spot
The flame front has to light a pancakeproblem is the far side lights itself
visualize the open chamber from the side at tdc
It is not pretty

 

[Curiousyellow71]

let's get clear
you can make great hp with an open chamber head as long as you keep the rpm above the torque (BMEP) peak
example: some stock classes
what sucks is on the street performance
I just do/did not build open chamber builds- go elsewhere except trailered cars
but then I do not run summit cams except for sale to used car dealers- but it is a better choice than a stock cam
never had a problem with valve bounce but I use asymmetrical lobes with carefully controlled close and the proper springs
The templets were for the earlier heads so BVVC with452 and similar- they work best with 902 and 915
now if you are building with a .050 down the hole and open chamber you have to back off on the compression and timing
problem is when you go to a thicker gasket and lower the compression you end up with the "use more throttle and make more heat" syndrome
so the temptation is to lower the compression even more
exactly what MOPAR did from 69> 73
Did not work then and does not work well now
but if you are on a tight budget you have to do what you have to do
Hints
minimize overlap and do not open the exhaust early- keep the valves on the seats as much as possible to keep the valves cool
do not lug the engine, keep it revved up when on the gas
no hot spots with open chamber???
The Plug is way down on one side and the other side is a long way off- the whole far side of the chamber is a hot spot
The flame front has to light a pancakeproblem is the far side lights itself
visualize the open chamber from the side at tdc
It is not pretty

I truely agree with everything your saying. Hot spots I wasn't very clear...I was referring to then ragged edges that other brands can have in the pistons and combustion chambers which get hot and cause detonation. My wording was poor.
I just dealt with a valve bounce on a comp cams nonasymmetrical XE in a pontiac... it was a recent learning experience for me so I mentioned it. The generic summit cams in which I was referring... those cam profile have been around forever. We installed most of them in the late 80s and 90s because our engine kit supplier only offered those generic profiles. The cam choices we have now are pretty awesome compared to then.
We aren't running any 906s currently and the one we did port make me appreciate a head porter that gets them to flow big numbers. The intake ports are so different between a 452 and a 906 I can't imagine the template being close to working...which I think u just mentioned.

 

[BSB67]

Nonasymmetrical. Funny.

 

[MO.RR]

The more I read the more machine work is coming into play. Say I deck the block to get piston either -.020 or zero decked, .022 gasket and stealth heads at 80cc. Stay stock bore stock stroke and one of the 256 cams wyrmrider suggested I believe I can still get by on 91. I’m still trying to keep it reasonably close to my budget.

 

[Curiousyellow71]

Nonasymmetrical. Funny.

I cracked myself up on that one trying to spell it...I like this new word for symmetrical ...but wait I was trying to type asymmetrical...Google corrects me when I don't want it then doesn't help when I need it.
Under the car in a tight spot I can't see with my glasses on...take them off.. can't see with them off. Then end up pissed off after I can't find where I layed my glasses.

 

[Curiousyellow71]

The more I read the more machine work is coming into play. Say I deck the block to get piston either -.020 or zero decked, .022 gasket and stealth heads at 80cc. Stay stock bore stock stroke and one of the 256 cams wyrmrider suggested I believe I can still get by on 91. I’m still trying to keep it reasonably close to my budget.

That combo is about 10.2:1 .05 below the deck... 10.9 .02 below which is awfully high..More compression will pull more vacuum then the lower compression...you could run more cam then. aluminum heads and quench I believe many run 10.5 :1 but with a cam that bleeds off compression.

 

[wyrmrider]

Pontiac wide valve seats and short springs heavy valves take some work
they and Olds and Cad are not SBCs
But the unwashed try to build them and MOPARs like SBC
does not end well