Winston Wolf wrote:I am thinking of swaping the heads on my .040 over small block Chevy 400. The bottom end is pretty good. Eagle crank, 6" rods with Mahle pistons (11.8:1 with 64cc) New last year, 500 miles or so on it.
I am currently running Gen 1 Trick Flow Twisted Wedge heads (64cc, 180cc intake runner) and a Comp Cams Magnum 292 Hyd cam (.501/.501 244 deg/244 deg @.050) I will be sticking with an Edelbrock performer RPM intake and AVS 800 carb.
It has worked well but the heads have 1.25" springs that never seem to hold up. I'm getting valve float again so I was going to switch out springs, but I'm thinking that I may just move to something more modern (heads are from 1997) that I don't have to worry about so much.
The car is a 1970 Monte, about 3700 with me in it. 4.56 gears and 3500 stall, I currently cross the line at around 63-6500 rpms.
The car is a street strip ride, and I don't get too concerned about streetability. I don't need to run faster than 11.50's in it because I won't install a roll cage. The car did 378tq/365hp on a chassis dyno last year, but I've done some tuning and the carb switch this spring and picked up a bunch from that (comparing old/vs this years timeslips took off 3 tenths and 4 mph)
I was thinking maybe some of the AFR Eliminator Race heads, but don't know a ton about them. I need lots of torque to get this big car moving, but it can take the revs, so I'm not afraid of that. I'm thinking 500 HP should be enough? With the cost of new heads I'm not sure if I will also be able to go to a roller cam, perhaps solid lifters would be ok?
I liked the twisted wedge heads, but I'm limited on cam choice with them and I think that is hurting me, plus all the monkeying around. I just put new Pro Magnum roller rockers on it, so I would re-use the 8 standard ones if I can. Maybe just a head switch is all I need and keep the current cam? I want to be somewhat budget conscience.
Thanks in advance.
BrazilianZ28Camaro wrote:About replace the TFS valve springs, I have these # LUN-73943 in my baby 292 SBC ...7200 rpm isn't a problem with a girly XE 274 cam
They have 1.26" OD and .630" max lift if memory serves me right.
They are the only ones at 1.26" OD I found that can work with .500"+ lift.
Hope this helps.
gmc406 wrote:Just outa curiosity, what did the curent setup run?
Winston Wolf wrote:
The Lunati spring:
Installed Height 1.750''
Installed Pressure 108
Open Height 1.250''
Open Pressure 339
Coil Bind 1.060''
Max Lift 0.630''
Spring Rate 462
Comp Spring I have:
Comp Cams #249-941-16
Single Outer Valve Springs
Seat load: 130lbs @1.750"
Open load: 350lbs @1.250"
Coil bind: 1.100"
What is on the engine now and seems to be floating:
Outside Diameter of Outer Spring (in) 1.260 in.
Damper Spring Included Yes
Spring Rate (lbs/in) 358 lbs./in.
Inside Diameter of Outer Spring (in) 0.875 in.
Installed height 1.750
Recommended Camshaft Style Flat tappet hydraulic
Installed Height (in) 1.750 in.
Seat Pressure at Installed Height (lbs) 125 lbs.
Open Height (in) 1.200 in.
Open Pressure (lbs) 325 lbs.
From reading it looks like I answered my own question and the 1.7installed - .501 lift - coil bind of 1.1 is ok at .099
It looks like I'm running my current springs right at coil bind, this, I am assuming has contributed to the relatively short life of the springs (my own stupid mistake).
I'm starting to think just sticking with what I have and installing these new springs with the higher spring rate will be just fine. I am a bit concerned about the seated pressure though, I don't know how much is too much for a flat tappet hyd cam.
bigcam406 wrote:if you did a head swap with the ones that were mentioned previously,and no other changes,you would notice a huge difference.that being said,without a cam change,you would be leaving alot on the table.id recommend the Profiler's and if your budget allows,why not go to a hydraulic roller setup?