How about these heads?

[71chmark]

My compression should be whatever came from the factory.

[Chryco Psycho]

so is the engine an HP or just a std 383 ?

[71chmark]

non hp 440

[Chryco Psycho]

ok so a non Hp 440 would be claimed as a 9.7:1 engine but in reality was probably closer to 9.4:1

[Super Blue 72]

ok so a non Hp 440 would be claimed as a 9.7:1 engine but in reality was probably closer to 9.4:1

Sooo, if he put on 915 or 516 closed chamber heads, do you think that would be too high a compression for premium pump gas? 

[ntstlgl1970]

Is premium in your area 93 or 91 octane?

[Chryco Psycho]

depending on head gasket used ,cam profile & real measurements , I think it will ping on pump gas with iron closed chamber heads

[71chmark]

So your saying 10.5 to 1 is to high for pump gas?  If not what other factors cause detonation?  What would you say is the highest horsepower you could get from pump gas (93 octane) and how do you get it?

[Super Blue 72]

?  What would you say is the highest horsepower you could get from pump gas (93 octane) and how do you get it?

I think StRoKeR's car is pump gas right?  Does 650 hp sound right?  I think I saw that somewhere....     

It's a matter of cubic dollars...... 

[oldkimmer]

.................The 516s do no flow nearly as good as the 915s, do not put alum heads on ur low comp engine as it will b pretty sad...........kim....

[Chryco Psycho]

not to start a fight but I can find no evidence to support the poor flow of 516 heads , once the valve size is enlarged & hardened seats installed & the ports are blended & or ported in the 516 they seem to flow with any other factory head which is not super but still decent , my Duster made over 500 HP & ran mid 11s with 516 heads in street trim with wipers heater , carpet , & stock seats & weighing in at 3440 with me in the seat & I only weight 160

[71chally416]

The problem with stock BB heads is they have the sparkplug in the worst possible place like the 1st gen SBC. Trying to build one with any kind of compression that doesn't detonate is like trying to build a V-10 for gas mileage. I would err on the low side of compression, like 9.5 at most and run more spark lead instead of running higher compression and having to back the timing off. And the best stock BB heads I've seen on the flow bench are the 906's. They have the best short side radius. Some of the older heads have a flat floor in the intake ports and don't even have a short side to work with. It doesn't much matter at high lifts but the 906's will outflow the others in the lower lifts. They would probably be best for a mild street cammed motor. Just my

[Chryco Psycho]

sure but no difference between 516 & all other BB heads

[71chally416]

http://www.moparmusclemagazine.com/techarticles/5115_cylinder_heads/photo_03.html

[Changin Gears]

Bumping up the compression to the absolute max does not have the pay off you might think.  According to the  chart in David Vizards book 'How to build Horsepower' going from 9/1 to 10/1 compression nets you 1.7% more power (6.8 hosrpower with a 400 horspower engine).  Is it worth living on the edge, risking a bad tank of gas in anything other than a max effort race car? While more is better, its not that much better.