7854ġ/2 stroke + rod length+piston pin compression height,ĭue to head gasket thickness and what the piston deck height is are commonĪ good set of BBC heads with a 2.30 inch intake valve, header primary's 38" long with 2" pipes and 3.5" collectors about 20 inches long, can flow more than adequately for the 496 BBC that will rarely see over 6500 rpm in a street/strip engine combo. Yes Im assuming its a tall deck 10.2" block and a 4.25" strokeĪ 4.25" stroke,6.8" rod and 1.270 pin height, for that 10.2 deck height blockĦ.8" rod divided by a 4.25" stroke=1.6 ratioĭisplacement = bore x bore x stroke x 8 x. What length connecting rod and what piston pin height are you using, building the 496 BBC? When you see guys selecting long duration cams in a 496 BBC with only 10.7:1 compression thats intended to be used with pump octane high test fuel, they are generally trying to compensate for poor flowing cylinder heads, adding duration allows more time for the ports to flow but results in a lower effective dynamic compression ratio. This will place you in the larger oval port and smaller rectangle port standard bbc head configuration range.
IF you wanted to use the cams listed in the link boosting the compression too between 11.5:1-to 12:1 and use of race octane fuel would be required, to allow the full potential.Ī 496 bbc will generally use a port cross sectional area near 4 sq inches.
580-.600 range in a hydraulic roller cam, if your want to maintain, a reasonably long and trouble free use as daily transportation. The 10.6:1 compression results in calcs that show that the intake valve should seat at about 70- 73 degrees past bdc and intake duration should be in the 240-245 range with exhaust duration maybe 5-7 degrees longer and a 105-106 lca, this is very likely to limit lift to the low to mid. 050 lift, and oval port heads, youll almost always find a single plane intake has some advantages over a dual plane intake.
Yes you could use some of the better flow rate, 280cc-290cc oval port heads to get a bit more low and mid range torque but at a minimal reduction in peak powerītw heres a tip learned through experience, if your 496 -540 displacement BBC combo includes an engine with at least 10:1 compression and a cam with at least 240 duration at.
If youll spend 90% of your engines operational life at under 5800 rpm it makes very little sense in my opinion to build the engine for peak power over about 5800 rpm, just for a couple hp you,ll very seldom have access too, it ,makes more sense in my opinion to concentrate on durability and drive ability, in that 3700 rpm-6000 rpm youll need 90% of the time, and maximizing the torque curve, THE 496 DISPLACEMENT AND 10.5:1 COMPRESSION WILL PROVIDE PLENTY OF OFF IDLE TORQUE FOR STREET TIRES SO A SINGLE PLANE INTAKE WOULD BE FINEĪnytime you start to assemble a list of matched components where your intent on building that engine to meet a certain power and rpm limitations you need to mentally step back and do the math thats required to keep all the parts you select, are kept with-in that intended power and rpm range, and while looking closely at both the financial budget and the component stress limitations, and you'll need to keep in mind fuel octane youl use,and the drive train gearing and vehicle weight ,and the probable durability and traction limits its likely to be used under. Now he may make very good peak power with the cams he listed, but he will sacrifice a bit of low and mid range torque that the properly matched cam would provide that would still produce very good peak power.įROM PAST EXPERIENCE, IF YOUR GOAL IS MAX POWER, I'D SUGGEST A CYLINDER HEAD THAT FLOWS IN THE 350 + CFM RANGE AT. Its rather obvious that the guy posting this, is looking at cams that have a good deal longer duration and more lift than the engine is likely to run correctly with.
I found this question posted else ware ( quote below) and just for giggles I ran the info data through the math and as is very common,