Ol Dirty T said:I'm looking for a second opinion on a cam suggestion I received from Comp Cams for my 65 impala.
Here are my specs
406 c.i.
5.7 rods
9.88:1 compression
Trick flow twisted wedge G2 heads
67 cc combustion chamber
190cc intake
82cc exhaust port
2.02 intake
1.60 exhaust
3.31 rear gear
700r4 stock stall (1400)
edelbrock performer intatke
edelbrock 600 cfm performer carb
tube headers
My existing cam is wrong for this setup -
it's a Crane Compucam 2040 .210 intake @.050/.210exhaust @ .050
lift .440 int/.454exh.
I realize my carb and intake are on the small side. I'm considering a performer rpm air gap and a 750 edelbrock carb.
The cam suggested by comp cams is a XE262H
218 intake@.050/ 224 exhaust @.050
Advertised duration 262int./270exh.
lift .462 int/.468 exh.
Will this cam liven it up? Should I step up to the the XE268 grind? (duration @ .050 224 int/.230 exhaust, lift .477 int/.480 exhaust.
If I left anything out, let me know. I appreciate any help you can offer.
before anyone can recommend a reasonable cam, up-grade, think thru your goals to have a complete package, matching your particular application, it would sure help to know why you think the current cam is a miss match and what potential changes in performance your looking for with the new cam?
yes your current cam is a bit small in duration to maximize the 406 sbc potential, it most likely starts to be restrictive by about 4000rpm, but the stock stall converter and 3.31:1 rear gear does limit the potential choices as your very likely to loose low rpm response and torque faster than you gain peak power if you just jump into a significantly longer duration cam. now thats not to suggest you can,t make a good improvement in performance, as those heads, the displacement and compression ratio all suggest you have far more potential that can be un-locked with a larger duration cam, but it will not be a great idea to just jump up without doing a few calculations and knowing the engines clearances and limitations.
everyone has different expectations and most guys looking for performance have a good deal more tolerance, for a lope in the idle or an engine that won,t pull smoothly from just off idle at part throttle, but Id be the first guy to tell you a really significant increase in cam duration, that will allow that engine to breath and produce a very noticeable power increase, will REQUIRE a higher stall speed converter to get it to function correctly, thats one reason, along with the cars weight,that the COMP CAMS recommendation was still rather low duration.
heres that crane cam, notice the durations 210/216[/color] what are you after? low rpm , off idle torque is not going to improve much with a longer duration cam,but match a cam and a converter and youll see improvement. Im using a set of reworked and ported twisted wedge heads on MY 383, and they provide very good power potential,
viewtopic.php?f=32&t=430
obviously talk to the cam and higher stall speed converter companys, about the cars weight, intended use, rear gearing, and transmission, valve train , and piston to valve clearances and potential limitations ETC. before you purchase any cam.
YEAH! THERES A HUGE TENDENCY TO WANT TO IGNORE OR SKIP THE LINKS AND SUB LINKS,
DON.T IT COULD SAVE YOU THOUSANDS OF DOLLARS AND WEEKS OF WORK
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http://www.summitracing.com/parts/lun-1 ... /overview/
http://www.summitracing.com/parts/lun-10120703
theres little question that the slightly longer duration lunati cam will produce a bit more peak power in your particular combo, but it would also NEED the higher stall speed converter and a 3.73:1-3.90:1 rear gear change even more than the slightly smaller duration lunati cam to allow it to perform to its full potential, and be even MORE restricted, if it were installed, without the required matching drive train upgrades ,if you don,t make those matching changes to the current combo, swapping to the longer duration cam will more than likely REDUCE performance even though it potentially could help unlock a good deal of the engines potential, if thoses matching mods were done!
every choice is going to mandate some careful choices to maximize its potential.
