I'm in the process of selecting a cam and would like your input on a few things.

Heads are Lt4...here's the flow #'s

intake 137.6@200
198.9@300
239.3@400
272.2@500
298.1@600
295.8@650
293.6@700

exhaust 109.5@200
148.1@300
178.7@400
199.6@500
214.1@600
218.9@650
223.8@700

K&N cold air kit
58mm ASM TB
intake is Lt1 port matched to the Lt4 heads
hooker long tubes 1 3/4"
gears are 3.42 now but will probably be going with 4.10 soon

I'm planning on going with a hydraulic roller cam with the following specs:

intake duration 234@.050
exhaust duration 242@.050
lsa 110
lift 612

The car will predominantly be driven on the street but will not be a daily driver so I'm fine with leaning towards a more aggresive/less streetable setup. What do you think about the cam specs and what kind of horsepower can I expect. Will the factory fuel system with a supplemental inline pump and an adjustable fpr be able to handle it?

Thanks,
Jason

 

Depends what its going into. If its the 409ci in the sig, I would probably go even a hair bigger than that. For something 396+ci, I would be looking at a hydraulic roller that is upper 230's/240's. And you really cant hurt yourself going with more lift inless you run into piston/valve clearance issues.

If its a heads/cam 350, I'd go smaller. No larger than say 230/240.

If it is for the 409, seriously, get a custom grind from LE, Joe Overton, or Bret Bauer.

 

As for the stock fuel system, an inline pump would definatly supply enough fuel for something all motor like that.

But it would be a smarter/better move to go with the Racetronix 255lph Kit with the new harness. It will support around 650-700RWHP on motor, and 550ish on boost. I think it is around $250 dollars, and then the time to take the tank out and such. But it really wasnt that bad. I did mine in my driveway in a few hours, fighting ****ty weather, trying to do it between storms.

 

yeah it will be for the car in my sig

 

I would definately go bigger than that in a 409. Those extra cubes will really take the bite out of something similar to a GM847. If you're looking for something that's going to be wild in the 409, I'd think you would be looking for something in the low 240 range on the intake side and the high 240's on the exhaust. It's obviously going to depend on the profile of the lobes, but I'm thinking you could do something like a 242/248 and be totally driveable. (Or at least what I would consider "driveable")

 

Yea, I am a little picky about driveability/practicality but now that i know its for a 409ci motor, definatly would want something in the upper 230's even lower 240's intake, and upper 240's exhaust. You would know it's in there, but it shouldnt have any problems with driveability.

You should come up with some full specs on cams your considering, and see what everyone thinks about them. I'd even consider PM'ing Bret, Rich (RSKrause), etc. as they are very knowledgable and could help you more than I could. I can tell you this though, with a motor that size, you cant to start looking at cams a little longer in duration, with a bit more overlap ( Which is a by product of LSA and Duration ), and the heads flow well up high, so why not get a cam that takes advantages of the head flow. Run a little higher lift.

Good luck with it.

 

what the compression ratio are you going to run?
Im asking because the comp and the cubes are going to eat up the cam. I would think you could go a decent amount bigger and still be very driveable. If you stay with the cam you already have i think you ll be cutting yourself short.
Your heads are dam near 300cfms, get a custom from bret, le, ai, joe oveton, so you get all the power out of the motor you can.

 

compression ratio is around 10.9:1

thanks for the input...keep the suggestions coming, I'm all ears

 

I checked with my cam guy and he said the specs he gave me are pretty much the limit for a hydraulic roller cam...do you guys agree? I'm pretty sure I wannna stick with the hydraulic setup, atleast for now.

How do you feel about a stud girdle for my application?

 

There are a million choices, well actually an almost infinite number of possible variations. What size is the intake valve - that is very important as it is the relationship between the intake valve size and the bore/displacement that primarily determines the rpm range of the cam when duration is figured in and also allow the LSA to be optimized. I would look to peak in the 6,500rpm range.

I agree that the fuel system you have chosen is illogical. The stock pump MAY be adequate, I am not sure. But if it isn't, a bigger intank is the way to go.

Rich

 

Intake valves are 2.080
Exhaust valves are 1.600

Will my stock injectors be able to handle the demand or do they need to be upgraded as well?

 

Gonna need new injectors too. Probably something in the 40# hour range.

 

Hardcore is on the right track! That is a seriously undervalved engine, more like a BBC than a small block. Look at it this way.

350 with 2.02" valve = 21.7in/in^3
383 with 2.02" = 23.7
409 with 2.08 = 24.6
454 BBC with 2.25 = 25.2
469 BBC with 2.30 = 25.5

This means you need to tighten up the LSA. I'd look for ~80-85 degrees of OL based on advertised duration. Your cam, assuming AD of 285/295 is 70 degrees, not nearly enough. I would tighten up the LSA to 108 and go with ~5 degrees more duration. That will give you 80 degrees of overlap and it will work much better. You need a custom cam, you have an unusual combo. More detail will cost $$$ to somone. You may wish to PM me, but that should put you in the ball park.

Rich

 

By comparison. look at a 302 SBF.

302 with 2.02" = 18.8!!!!
331 with 2.02" = 20.5

Any wonder they need different cams?

Rich