396 question for Joe,Injuneer,Performin et al,,,,

[TimeLord]

I am having my 350 turned into a 396 this winter,it will be 6.00 rods with the appropriate crank and pistons.

My question is do I need a new cam bigger or smaller than my LT4 Hot Cam,I am most probably reusing my actual heads that flow 234 @ .550.

My car or parts wont hit the shop (ZEKES) for another month or 2 and I just wanted an idea of where I was going.

The parts I am buying from my friend Rick and they are all top notch,magnafluxed and balanced.

This should give a torque motor more than a HP beast,is this correct.

It will still be daily driver and not a trailer car so I want to keep it civilized.

Thank you!!

RICK

[Joe 1320]

You'll find that the extra cubes will tame the cam down just a bit. I think it's going to depend on what your defination of streetable. If you liked that cam with 350 cubes, you will be able to step up to something a little more aggressive without really losing anything. The extra cubes and more modern tech cams will ensure that.

[TimeLord]

Thanks for the quick response.

Streetable to me is daily driving in town and 280 mile round trip to the track 17 weekends of the year.
With my current set up it is a nice lope and 23 mpg highway.
Would a new cam be higher lift and longer duration or the reverse,I have never really shopped for a cam,last time I looked the LT4 HC was the hot ticket!!!

[fastTa]

The hotcam (218/228) will basically be swallowed by 396 cubes. You can go significantly larger without sacrificing any streetability, but based on your conservative head flow numbers, it would appear that not much has been done to your heads so you will need to match a camshaft to your head flow and port velocity characteristics. I guess it will just all boil down to whether or not you're concerned with emissions.

If all you are concerned with is torque, then why not go for a 409ci? Maybe you already have the crank purchased.

[TimeLord]

The rotating assembly I am getting from Rick is 396 and at the $$$ he is selling them to me(THANK YOU RICK)I cant let them pass.

The heads may be replaced with his Twisted Wedge heads that flow 266 if he can get his new ones done in time.

[Joe 1320]

As was pointed out, heads are going to be the key. With your converter, it's loose enough to let you get a little wilder with the cam choice without cutting into drivability. You will need better heads or the top end pull won't be satisfactory.

[TimeLord]

Is there any make you recommend over another.

I know I have heard good things about FUTRAL,Madman has quick cars also.

Is the cc306 passee or is it still a good choice!

[Trash man]

some1 asked bout that and i forgot who shot it down, i guess its a 20 year old cam? ill look for the thread

[TimeLord]

Crankshaft=3.875 stroke

Rods= 6 inch

Pistons= Flat top 402gr.

Overbore=.030

Head volume= 58cc Thus 12.0 to 1 compression.

My present cam is LT4 Hot Cam 218-228 ,112 LSA, .525 lift with the 1.6 RR,it will be too mild for the 396.

To run with a nice lope (not 2 violent) similar to my present set up do I need to increase or decrease my LSA.

Is 230-240 too violent,

[fastTa]

Crankshaft=3.875 stroke

Rods= 6 inch

Pistons= Flat top 402gr.

Overbore=.030

Head volume= 58cc Thus 12.0 to 1 compression.

My present cam is LT4 Hot Cam 218-228 ,112 LSA, .525 lift with the 1.6 RR,it will be too mild for the 396.

To run with a nice lope (not 2 violent) similar to my present set up do I need to increase or decrease my LSA.

Is 230-240 too violent,

It's is going to depend largely on the total overlap on the cam and the split between the intake and exhaust duration.

Here is one way to calculate total overlap by using the advertised duration and LSA(lobe separation angle). Their are slightly more accurate methods of determining total overlap, but they involve IVO and the EVC event timing and we'll save that for another day because it gets deep . For now this works fairly well.

First you add the advertised intake and exhaust duration together. Then you divide that sum by 4. Then subtract the LSA. Then multiply that by 2. Below I will use my CC306 example. You will obviously just need to use your own values:

290+307 = 597
597/4 = 149.25
149.25-112 = 37.25
37.25 * 2 = 74.5

So the total valve overlap is approximately 74.5° for this CC306 camshaft. That is a fairly bumpy cam for a stock displacement motor, sometimes even in larger motors.

A proper camshaft can really only be determined once you have data like head flow, short side radius, port cross section width and port velocity, but generally speaking, anything over 230 in 396 cubes is going to have a bumpy idle. It will all boil down to how your tuner is. Large cams can be made to idle well and not cause unwanted cam surge.

[Joe 1320]

It's is going to depend largely on the total overlap on the cam and the split between the intake and exhaust duration.
.

And with that increased overlap comes a higher rpm powerband.

[TimeLord]

Is increased overlap + than 112 or - than 112 !!

[fastTa]

Is increased overlap + than 112 or - than 112 !!

The wider the LSA(higher number), the less valve overlap. The narrower of a LSA(lower number), the more valve overlap. So anything less than 112 will have more valve overlap.

[TimeLord]

Thank you !!

[TimeLord]

Filled out the Comp Cam request form and got this back!!

Cam Spec Card Inquiry
PART NO. 08-467-8
01 INTAKE MASTER 3016S
02 EXHAUST MASTER 3037S
03 ENGINE CS 280XFI HR-13
04 GRIND NUMBER CS 280XFI HR-13
INT EXH
05 HYDRAULIC Y/N YES 14 DUR @.050 230 236
INTAKE EXHAUST 15 LOBE LIFT .3610 .3580
06 VALVE ADJUSTMENT HYD HYD 16 ROCKER RATIO 1.60 1.60
07 MAX GROSS VALVE LIFT .576 .571
08 DUR @ .006 TAPPET LIFT 280 288 17 LOBE SEPARATI 113.0
18 ADVANCE 4
09 VALVE TIMING OPEN CLOSE 19 VALVE SPRINGS 26918
@ .006 10 INT 31 69
11 EXH 81 27 DATE SETUP 10/18/2004
12 THESE SPECS ARE FOR CAM(S) INSTALLED
@ 109.0 INTAKE CENTERLINE

13 REMARKS