Hey guys. Currently I am runnin E6 heads on my 302 cause they're all I could find when I was building the motor and they were cheap. They have been gasket matched and have higher lift springs in them, but I think they're holding my engine back. The way the motor is built, I would think it would pull good to about 6,000 or 6,500 rpms, but it kinda dies off around 5,000. I have taken it all the way up to 5,500 but there's not much power up there. Would a set of E7's or GT40's with a little bit of port work do much for me or should I save up to get some AFR's or something (this could take a while as I am a broke college student)?
E7 with a little port work or just stock gt heads (40 or Ps). I still pull up to 7000 rpm with gt heads. I got rid of the P heads due to the fitment issues, but running GT40s now, I get a nice torque curve from 3000 through 7000 rpms. It doesn't stop pulling, but I do. I am afraid to go over 7k. Be sure to get a good set of springs and make sure it all works together.
Thanks. I guess I'll just keep an eye out on craigslist and wait for a set of GT40s to pop up. Or I could get them from a late '90's Explorer correct? They have a bunch of them at the Pull-A-Part back home.
96 and 97 explorers, maybe some 98s. Just watch out for the bars. 4 vertical bars is GT40P which are difficult to hook headers up to. Look for 3 bars. Also found on Lightning trucks, some 5.0 mustangs, I think the cobras or something like that.
The P heads are actually a little better because of the relocated spark plug and slightly better exhaust port, but as was mentioned the problem is finding headers to fit. There are guys that run high 11s on STOCK P heads in a full weight fox body, so with the right application they certainly have enough potential. There are guys that can even get into the low 11s on "stock" P heads, but it takes a lot to do it. I probably wouldnt expect to run those kind of numbers unless you really know what youre doing, as a lot of supercharged cars cant even run those numbers. At any rate, milling a set of non-P heads .035-.040", cleaning up the ports a little, and adding a set of stock used LS1 beehive springs will make a world of difference. Dont even try to use the stock Explorer springs as theyre only good for stock cams, and only barely so, not to mention heavy. Youll probably have to go buy a tool to cut down the diameter around the guide so the springs fit, but it shouldnt be more than about $40. I have a set of used gt40 heads (untouched) laying around if youre interested, and would be willing to do the work I mentioned as well.
My turn! (only child, so get used to it!) There is not much to port out on GT heads. I learned the hard $250 way. Found a water jacket where it should not have been. They flow fine and should get you moving into the 11s without mods, other than new springs and retainers to handle your new motor (they are made for roller cams, not flat-tappets). The Ps do run better due to the spark plug angle etc. but it is a major hassle to use them on our cars. The non-Ps are almost as good, but the ability to get to your spark plugs way outweighs the loss of performance, which is only a couple of cfms over the regular Gt-40 heads. So, if you have a couple sets of 40 heads sitting around, I am sure someone here will snatch them up. I have had no less than 5 PMs looking for them in the past week.
Out of the box, the E7's make 25 more HP over the E6's. No amount of port work will help the E6's. The valves are sunk into the head 1/8" deeper than all other SBF heads. This shrouds the valves, you could open the chambers to unshroud them, but at 68 ccs volume to start with, you really don't want to go there.
Cool. 25 more horses would be real nice. With the current setup, I have run a best of 9.06 (1/8th mile). I want to get the car into the mid 8's. I hope that a little carb tuning and new heads will get me there.
Hi heres my opinion on this.The E7s are very good if you are on a buget,just port match and clean up under the valve.The GT40ps are very very good,some porting that can be done by yourself.If your not that good at porting these heads,just clean up the rough edges and port match.But you may have a problem with headers,some guys have been able to reuse thiers.I myself have not seen enough gains from the GT40`s or older darts.But hey have fun
Well if that's what you're after, then you might want to stick with the E6's. The 86 Stang's(E6 heads) turned in lower 0-60 mph times and slightly quicker ET's than the 85's did. And virtually was a dead heat with the 87 Stangs (E7 heads). The E6's deliver excellant bottom end, but as you've found out, run out of breath after about 4500-5000.
Well I figured if the E7s are any better then they are worth it to me because I can get a pair for as low as $20 used around here and all I would have to do is gasket match them then swap my springs and rockers from my E6s onto them and I would only be out about $30-$40 max.
