Worse combustion chamber design ever? Saveable?

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MopaR&D said:
I think it's the wall on the side where the spark plug is that has the most negative effect since it's shrouding the part of the valve where the most flow happens. The air/fuel mixture doesn't flow uniformly around the valve head, most of it flows across it out the side opposite of the intake port. The mixture has momentum and would rather go straight than turn down to go into the cylinder. Big reason raised intake ports are a thing, makes the path into the cylinder more straight.

If you look closely at the pics of the 302 or early closed-chamber 273/318 heads they all have that wall at a much shallower angle and curved away from the valves and the top goes all the way to the edge of the cylinder bore. The more modern chambers (Magnums, aftermarket) have the top of the wall pulled in a bit to make that second small quench area but it's still curved as much as possible so as to not shroud that side of the valves.

I've also heard somewhere before about those one-year-only Ford heads and how they killed power. Not sure what they were thinking it is pretty terrible. Then again IMO Ford has a history of "innovations" that didn't work as intended lol.
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Agree

You can work that part of the chamber on. J head and pick up numbers. Long ago when i was equalizing chambers on a heavily ported j ...after working the far side around the plug... i figured that out.
 
Anybody have photos of a perfect or near perfect chamber for efficiency and power? Modifications made to make it work better?
 
toolmanmike said:
Anybody have photos of a perfect or near perfect chamber for efficiency and power? Modifications made to make it work better?
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Yeah, here you go. Perfect chamber.

CUMMINS.jpg
 
That could be interpreted in a lot of different ways. When you start scienceing something that hard, piston shape becomes becomes as much of a priority as chamber shape. For us it’s probably a 3rd Gen. Hemi chamber.
Completely unrelated, but a good example of how it applies, is the chamber and matching piston from the Yamaha YZ-450F. 53.1 hp at 9700 rpm from 449 cc’s, or 28 cubic inches.

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View attachment 1715672720

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toolmanmike said:
Anybody have photos of a perfect or near perfect chamber for efficiency and power? Modifications made to make it work better?
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Just Google “soft” combustion chamber and you’ll get a ton of pictures. I’ve been using soft of softer chambers for years. And yes, you can have a small, soft chamber.
 
You can tighten the quench as tight as you can or close to zero...or open it up and rid it completely 'see below' or take some timing out of it. There are important factors to consider on which approach to take.
First place for detonation to play peekaboo is in the quench area, forced and nitrous more. Obviously you approach each differently. So there isn't a one size fits all, and more to consider is the parts package and or 'shortcomings' and 'make dues' to work around/experiment.

Soft chamber vs hard chamber, same head
I know what you're thinking..
Yes thats exactly what it looks like, going backwards... but for fairness and in keeping with "cat skinning".. its up to the builder and only the track/dyno will tell the truth and i for one while i like a good chamber...air flow is king and chambers can get in the way. Balance... is at your discretion.

CC dome.jpg
 
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MOPAROFFICIAL said:
Soft vs hard


Yes. It's exactly what it looks like and itself

You can tighten the quench as tight as you can or close to zero...or open it up and rid it completely 'see above'...or take some timing out of it. There are important factors to consider on which approach to take.
First place for detonation to play peekaboo is in the quench area, forced and nitrous more. Obviously you approach each differently. So there isn't a one size fits all, and more to consider is the parts package and or 'shortcomings' and 'make dues' to work around/experiment.
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A soft chamber and quench are mutually exclusive. You can have both.
 
The early Hemi is a soft chamber and can have quench depending on the piston.
 
Here’s one picture of what I’m talking about. You have to scroll down the article because I can figure out how to just copy the picture.

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Ok...I figured it out. That’s a soft chamber with quench. Maybe I can find another one that’s not LS based.

...
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A soft Hemi chamber
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A soft 385 Ford head, but it’s for the hose so they took away the quench pads.

Edit: I believe this head is NOT a a 385 Ford head. I think it’s an Alan Johnson 481 X head. I had to look at it a bit closer. Had one of those on my flow bench. Remarkable head for 2000-2001 when I had it on the bench.
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Pretty soft SBC chamber.
 
Some of the higher end Cleveland heads have soft chambers and quench.
 
RustyRatRod said:
Yeah, here you go. Perfect chamber.

View attachment 1715672721
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That is the bee's knees for diesels but works like crap in gas engines. That's what the early Jaguar V-12 head was like, flat with no chamber and the chamber was in the piston. Part-throttle combustion was so bad and it had so little tolerance to mixture variance it couldn't pass emissions. They designed the H.E. head with a fast-burn chamber and it was far more efficient. They were able to run high compression ratios with lean mixtures and pump gas just like with a well-built wedge-head V-8 with modern chambers like we see all the time. But then there was a trade-off with slightly reduced flow since the valves were no longer completely unshrouded like in the non-H.E. head. As you can imagine the early heads are typically recommended for all-out performance but the H.E. is recommended for street or dual-purpose use.

...I'm somewhat of a closet Jaguar guy lol hope to someday own one. Same goes for old Buicks. And a lot of other stuff tbh
 
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MopaR&D said:
That is the bee's knees for diesels but works like crap in gas engines. That's what the early Jaguar V-12 head was like, flat with no chamber and the chamber was in the piston. Part-throttle combustion was so bad and it had so little tolerance to mixture variance it couldn't pass emissions. They designed the H.E. head with a fast-burn chamber and it was far more efficient. They were able to run high compression ratios with lean mixtures and pump gas just like with a well-built wedge-head V-8 with modern chambers like we see all the time. But then there was a trade-off with slightly reduced flow since the valves were no longer completely unshrouded like in the non-H.E. head. As you can imagine the early heads are typically recommended for all-out performance but the H.E. is recommended for street or dual-purpose use.

...I'm somewhat of a closet Jaguar guy lol hope to someday own one. Same goes for old Buicks. And a lot of other stuff tbh
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348/409 similar
 
MOPAROFFICIAL said:
348/409 similar
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Yup but at least those had the benefit of the slanted deck so it was arguably better and still pretty much a wedge chamber. The Jags were "straight" so the only place for the mixture to go was a bowl in the piston and even with quench that just doesn't work well in spark-ignited engines.
 
MopaR&D said:
Yup but at least those had the benefit of the slanted deck so it was arguably better and still pretty much a wedge chamber. The Jags were "straight" so the only place for the mixture to go was a bowl in the piston and even with quench that just doesn't work well in spark-ignited engines.
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Yep and crower made the pistons for them so they could even be competitive .
 
Garrett Ellison said:
I can imagine that a few racers have done some weird things with angle milling that block before.
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Not a whole lot, the bolt holes will pointing the same direction as set at stock deck angle.
Hog out some head bolt holes and face head bolt lands to the right angle. Probably room some, but it just multiplies with length and gets worse at the far end.
 
Garrett Ellison said:
I can imagine that a few racers have done some weird things with angle milling that block before.
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Maybe. Most high compression pistons are right there, almost zero deck height, so it depends on the piston choice.
 
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