I'm getting ready to try out my new Jeg's 197cc heads (2.055/1.60 valves) 65cc chambers. Combo is 355 sbc, 9.5 to 1 comp., 750 Vac. Holley, Edelbrock RPM intake, Crane Energizer 284 dur. .480 lift hyd. cam, 110 gph mech holley fuel pump, Hooker Super Comp 1 5/8 headers to 2.5 in. to 40 flows dumped at axle. Car pulls hard all the way up to 5400 in first gear then noses over, 2nd gear can go a little higher. My ported 461's pulled higher rpm's than this! Any ideas? Spring pressures are 135 seat and 290 open, heads are set up to go to .740 lift. Am I running out of cam (lift?) or fuel, car doesn't sputter or pop, it just falls on its face. Going to run T/O's Sunday if it doesn't rain, car ran a best of 13.84 at 98.7 mph on street tires with the old heads. It doesn't feel like it'll do any better by the ol' butt dyno. These heads are supposed to be canfields. Running th-350 pro built full manual with 3000 convertor, 3.36 gear and 28" tires. Any help would be appreciated.

Valve float? how did you lash the valves?

Balancer is indexed at 90* increments, adjusted valves through firing order to zero lash (this was the way crane instructions read) then 1/2 turn more and polylocked. I have adjusted the valves several different ways but this way works best with this cam. Lashed that way on the old heads also but it pulled to 6100 rpms.

Originally posted by KS64SS:
Balancer is indexed at 90* increments, adjusted valves through firing order to zero lash (this was the way crane instructions read) then 1/2 turn more and polylocked. I have adjusted the valves several different ways but this way works best with this cam. Lashed that way on the old heads also but it pulled to 6100 rpms. =
When you say the springs are 135 seat /290 open & set for .740 lift is this what you were told by where ever you got the heads??
Those numbers don't make a lot of sense
How much pressure do you have at .500?

The hang tag read 290 open at .540 lift, dual springs.

So you havent changed anything except the heads? just a head swap,not a cam swap or rebuild? ignition?

sorry hit the button too soon, cam rerquires 105 lbs at 1.700" and 280 lbs at 1.240". Probably don't have enough open spring pressure. My info is at work so I don't have it with me right now.

Haven't changed anything at all, just the heads. Although I failed to mention I am running an HEI unit with a stock module, now I wonder. Locked out at 34 degrees.

Thats a good place to start...those modules usually give up around 4500 or so.

Does someone has some documention of the HEI modules and the 4500-5000 rpm myth? I was suckered into buying an accel one, and it never did anything on my old rig. Felt the same, et's were the same, same rpm.

I have a stock GM one now and turn 6500rpm easy, and my buddy with the same goes to around 7k.

I really want to know if this is a worthy thing to purchase?!


Other than the valve float, I'd lean towards fuel. Seen lots of cars fall on their face early from lack of volume...

well I just got back from the strip(first time out with this car) and I have the exact same cam in my 406. I don't think the cam is holding it back, Could be that stock hei/module, I run an accell 300 ignition in mine,
I was shifting at 6000-6200 and it never missed a beat it was still pulling hard at 6200. I have world products S/R heads with the small valves(1.94"/1.60) with some mild porting.
I am running a carter mechanical fuel pump and a 750 with #77 jets in the back and 74's in the front I don't think that cam will do much for you over 6500 rpm but it should pull pretty hard until then. I have an open 10 bolt with 3:36 gears and was running street tires, had no traction at all, I was hitting 98 mph but was only able to get 14.3 out of it because it was just roasting the tires for the first couple hundred feet

Never had a stock HEI module go bad but the coils sure do. They have a bad habit of working fine until you put a load on them. See if you can borrow a coil from someone and give it a try.

Hey guys thanks for all the replys. I'm leaning toward a fuel problem or ignition problem. It's been nothing but tornadoes and heavy rain since yesterday evening, don't know if i'll get T/O's today or not. I'll let you know what it ran or what we found if we run. Thanks again. graemlins/waving.gif

definately fuel or spark I would think, check the little things- I recently did a carb rebuild for a guy and had problems spinning over 5000, come to find out the carb gasket I used was catching on the fast idle adjustment screw under the choke assembly and limiting the throttle opening to only 2/3. The simple things sure get me some times. I haven't had any luck with the stock HEI, only when a performance kit is installed would they rev past 6000. The pickup should also be changed if you put a module and coil, the coating on the pickups seem to breakdown after years of use, you'll need to pull the shaft out to change it.

Looks like I found a bad HEI coil, I stuck in a back up and it winged right up 6000 rpm's with no problems, I'm satisfied with that. Didn't get any T/O's in today track is too muddy in pits, more like a lake. Now I need to upgrade my HEI, possibly going to try MSD's new Extreme HEI kit with the adjustable rev limiter in the module. Any ideas? Thanks for all the replys. graemlins/thumbsup.gif