ricknbird350

iTrader: (21)

i had my car dyno tuned a couple months ago. (the one in my sig) the motor was built for a supercharger. but never could afford one now that i have a daughter and house. anyways my cam is IN .534 EX .549 and 277/286 duration, he did some pulls and said all power was dropping off at 5300 rpms. he told me the duration is killin me. he told me this "Go with a cam in the 230/236 range for drivability and go in the 236/242 for all out power depending on which way you want to go." so crower said i only needed a 2000 stall for the cam i have. how do i find out what stall i would need if i got the cam he recomends?

also does anyone know a good cam with those kind of numbers?

96capricemgr

iTrader: (1)

Well for starters you are trying to compare advertized and .050" duration numbers.

With the low power falloff rpm I would suspect valvetrain issues. Though the cam looks to be maybe high 21x-220ish intake which is a bit on the small side. It should still pull higher though.

2000rpm is low for a stock motor you need to start getting information from better sources.

IMO for a car you want any performance out of a 2800 stall 9.5" converter from Edge, Yank or Vigilante is minimum. A quality 2800 stall in a b-body is fine for even some towing duty, hell I do some towing with the 3400 I have now. The old 2800 Edge was so mild at low throttle inputs passengers mistook it for stock, till I got in the throttle at least.


With the low static compression I would talk to a cam grinder about a cam to help increase dynamic compression and maybe consider swapping to a thinner head gasket if you can. It is frankly about 2 full points lower than a built NA motor would be and these should be relatively cheap and easy ways to make use of what you have.

ricknbird350

iTrader: (21)

i actually just replaced the head gaskets. they were .050" thick i went with a .030 felpro.

crower is the one that i bought the cam from, you think they mis lead me with the stall number?

96capricemgr

iTrader: (1)

THe Felpro is .039, there are thinner you could have used depending on deck height. Would not go back and do it again.

The Crower tech is probably more accustomed to dealing with older applications, with lockup and overdrive we are comfortable with a lot more stall than folks used to use.

I am sure the car drives fine with a 2000stall but for performance a LOT of bolton guys go over 3000 with a stock cam. Modern converters drive a lot better than old ones and like I said lockup and overdrive make things even more comfortable.

Do you know what springs you have?? IMO that is the most likely culprit for a 5300rpm falloff in power.

ricknbird350

iTrader: (21)

i dont actually have a 2000 stall in the car. i just got a transmission with a 2500 stall i think. i used to run a 6speed behind it. that motor loved that.

as for the valve springs the machine shop didnt say what they were other than they labeled them "advanced" spring pressure 105lbs closed 315lbs open if that helps

96capricemgr

iTrader: (1)

105lbs closed is pretty weak, sounds like they used a completely wrong spring.

LT1 valvetrain gets screwed up a LOT in part because people do not comprehend that the LT1's ultra short intake runners means more rpm for the same duration when compared to a gen 1 motor.

Maybe your cam would be fine with 5300rpms in a gen 1 where the long runners keep rpms needed lower, but an LT1 with the same cam often needs 500rpm more to use the same cam. More rpms means more inertia and more spring needed to keep things under control. Still that seems low so maybe they were thinking flat tappet gen 1 when they picked that spring, either way I can guarantee you 105lbs is not enough spring and you will gain rpms and power if you give the existing cam an appropriate spring.