Thanks, this is exactly the reason I come to people with more knowledge than me. This is a very helpful post. However I am thinking a bottle might be simpler and cheaper to get the car into the 11's after I get the carb dialed in. But heads would definatley bring more all the time HP to the table
What kind of piston to deck measurement do I need to make sure this combo will work? I was assuming my static was like 10-1 with the current setup assuming stock deck height.
For some long term thinking.......
If you go to NOx, you are just adding in more oxygen so you can add more fuel. That will raise the cylinder pressures and move towards detonation. So you probably aren't going to go with much NOx safely without higher octane fuel, because the present setup is already moving towards the limit for detonation on pump fuel with just the natural intake of oxygen via the carb.
The present setup is not optimum for fighting detonation anyway:
- The present piston to head gap is likely in the range of .110" + or -, and that will give you no quench effect.
- This large gap presents a larger, slow burning open chamber style area. Slower chamber burns increase the probability of detonation.
- The head are iron, which does the same thing.
- The DCR is already up there.
- More ignition advance needs to be done with care here IMHO due to this setup. Listen closely for detonation. (I've been in this territory before.)
- The prior owner may have found this out already. Let us know where you find the ignition timing setup as-is. BTW, you don't need a dial-back timing light to find you timing; just accurately extend the marks on the damper or put on a timing tape and use a regular timing light.
Moving to a closed chamber head like an Edelbrock with the right head gaskets will give you several advantages:
- AL heads that fight detonation
- A good quench gap that does the same
- A closed chamber where the burn is faster overall. Fights detonation and does not need as much ignition advance.
- Better flow that will help all over the RPM range.
The DCR is not going to increase very much with the change, so it is an improvement all over.
One thing to note is that if you go with Cometic head gaskets to get the piston-to-head clearance right for Edelbrocks, then the head and deck finish has to be in the right ballpark (50 RA) to hold the Cometic gasket. Just something to be aware of. It would be good to hear of anyone else using Edelbrocks out of the box with Cometics; we have, but that is just a sample of 1, and I did not check surface finish like I should have.
The key measurement is to find out how far the tops of those pistons stick above deck when at TDC. Head has to come off to do that... maybe a good thing when you put on that AirGap? Ooops.. too late! If you do that, then the present head gasket can type can be found out. (Or maybe you can get that info from the prior owner.) That will help firm up the details of what you have now.
And, of course, there are other options in heads.