Springs that would work good

Would be the edelbrock sure seat for the performer rpm cam or pbm #3100 or #3500. All three springs should work given the right installed height. 120 @ the seat and 300 or so open would be the way I would set the heads up.


Kyle

 

yeah, I sure wouldn't be using "good" stock springs with a cam anywhere near that size. They probably have around 60-70lbs seat pressure. Yes, I've heard BBC studs work well in the early ford heads. If I remember right, they are somewhat short and that helps so you often don't need to mill down the stud pedestals to get good geometry. I also agree that you should be looking for 110-125 lbs seat pressure and around 300 open. Also, don't use stock valves. They're known to come apart and ruin everything. Get some good stainless valves (not REV brand) and some good 7* or 10* locks and matching retainers. Check your valve guide to retainer clearance while you're at it.

 

yeah, I sure wouldn't be using "good" stock springs with a cam anywhere near that size. They probably have around 60-70lbs seat pressure. Yes, I've heard BBC studs work well in the early ford heads. If I remember right, they are somewhat short and that helps so you often don't need to mill down the stud pedestals to get good geometry. I also agree that you should be looking for 110-125 lbs seat pressure and around 300 open. Also, don't use stock valves. They're known to come apart and ruin everything. Get some good stainless valves (not REV brand) and some good 7* or 10* locks and matching retainers. Check your valve guide to retainer clearance while you're at it.

Thanks for the help guys.

 

i came up with these specs


Stock 1970 429 non cobrajet

closed 76 psi 214.7 open


1970 cobrajet/super cobrajet

87.3 closed 299.3 open


does the closed pressure have an affect on float?

 

This is going to sound Mickey Mouse but you can check the springs you have with a drill press and a bathroom scale.First,measure the installed height and remove the spring from the head.Put the bathroom scale on the drill press platform and use the chuck of the drill press to compress it to whatever height you want and you can read the lbs. pressure at that height off the scale.Use an old retainer to keep the spring from moving around and the nose of the chuck will fit it nicely.

 

yeah, the bathroom scale thing works pretty well. Seat pressure will have more to do with controlling valve bounce, not float. Open pressure is what prevents float. At any rate, you need more spring even if that turns out not to be the exact thing that's holding you back. And if you run more spring and rpms, you need better valves if you want to sleep well at night.

 

yeah, the bathroom scale thing works pretty well. Seat pressure will have more to do with controlling valve bounce, not float. Open pressure is what prevents float. At any rate, you need more spring even if that turns out not to be the exact thing that's holding you back. And if you run more spring and rpms, you need better valves if you want to sleep well at night.

thanks man

 

This is going to sound Mickey Mouse but you can check the springs you have with a drill press and a bathroom scale.First,measure the installed height and remove the spring from the head.Put the bathroom scale on the drill press platform and use the chuck of the drill press to compress it to whatever height you want and you can read the lbs. pressure at that height off the scale.Use an old retainer to keep the spring from moving around and the nose of the chuck will fit it nicely.

Holy crap, I never would have thought of that. :lol:

 

...BBC studs work well in the early ford heads. If I remember right, they are somewhat short and that helps so you often don't need to mill down the stud pedestals to get good geometry...Get some good stainless valves (not REV brand).

Scott,

Based on the info given by B429C, how can you be sure that the 1.75 chebby studs and guideplates will work and that you don't need to mill down the pedestals to "get good geometry?" How can you be sure that this is the case without knowing rocker arm brand and configuration, installed spring height, etc. (Was there more info/discussion in another post?)

Also, what's wrong with REV valves in a D0VE head buildup using the cam grind noted and it's requisite spring pressures? There are several performance levels of these valves and many use their product in much more agressive builds without issue.

Paul

 

I don't know that he'll be able to get by without milling down the pedestals. I've just HEARD that often BBC studs have threads that go further down and often allow it. I don't know what valve heights and rockers are needed to make it work. I personally have used REV valves in a sbc and had two of them lose the hardened wafer on the tip of the valve that's heat welded to the stem (this was with roller rockers and 130# seat pressure and 340# open). I'd posted it on the old bbf forum in a discussion about valves and one of the Evans (can't remember if it was Charlie or Lem) had also not had good experience with them. This was a couple years ago so maybe they've improved and maybe their better valves aren't crap.

 

Ouch, that must have sucked having that valve failure; I guess it goes to show that any component can pretty much fail at any time...

Paul

 

thanks guys i will check it out.