rmodel65

it has to do with how the flame front travels in the chamber...open 4v and 2v heads have the problems... http://www.network54.com/Forum/11941...d+other+issues

69mach1377

Did we read the same document you just posted?
"I was relieved when we found the (open chamber headed) motor was no more prone to detonation than the motors I assembled with quench combustion chamber heads."

rmodel65

i didnt read the document...i did build a 351c with 10.2:1 compression and it pinged a lot...really had to back off on the timing to get it to stop

69mach1377

My 2v headed Clevor actually required about 35-36 total advance, but it was about 10:1 CR. What did yours like?
Aluminum heads would have allowed more CR.

rmodel65

its been a while i dont remember what timing i was running i just remember a lot of pinging with 93 octane...i have the engine still it might end back up in my 65 one day

DocSnickers

hmmm I am not sure if my 4v heads are open or closed. Right now they have nothing on them at all. How would a tell what kind they are?

69mach1377

Compare them to googled images?
How are liking your GHG GT?
That would by my color of choice.

DocSnickers

It's great, been very impressed with the engineering behind this car. I do find the placement of cup holders to be bad. With the shifer being so small if you have any kind of drink in the first cup holder and sometimes the second it makes shifting interesting.

I do also find the shifting to be touchy, but all in all its a great Mustang lives up to the name.

dodgestang

You can't tell with them installed on the car. You have to take them off and physically look at the chamber. Open chamber is just that, the whole chamber is 4 inch round with 2 valves in it. Closed chamber is not a big 4 inch circle, instead somewhere between a D and a triangle shape....sometimes I hear it called a 'dove shaped chamber'

As for pinging, yes the 'theory' goes that the closed shaped chamber allows you to run a little more compression than an open chamber. I run 10.5:1 with an open chamber and have not had a detonation problem in my cleveland. I did have a detonation problem once when I was at 13.5:1 with a closed chamber though

DocSnickers

Will post some pic's here later this week with the heads.