70 ore 80 cc

[jteu2002]

i need new heads

engine 407 SBC

the cam i got

cam specs
flat tap. solid lifter
0.020 lifter rise

in 286 out 290
open 35 BTDC open 73 BBDC
close71 ABDC close 37 ATDC
lift .570 lift .580
lash hot .014 lash hot .016

overlap 72

0.050
in 258 out 262
21BTDC 59BBDC
57ABDC 23 ATDC

it was purchassed for mainly racing
but will it run on he street ?( so i can eat bmw porchas amg mercedes and that sort of stuff)

the heads i am thingking of are the 220 AFR 's
but go 70 cc ore 80 cc


on a desktop dyno i lose more the 40 hp with the 80cc

 

[grumpyvette]

Id really need to know your true static compression ratio, your cars weight, your transmission
(stall speed, if its an auto trans)
your cars rear gear ratio, tire diam.,
intake and carb or efi that's going to be used
and the type of headers, and any other info you can provide, to make a valid suggestion, but heres some guide lines.
that cams designed to be run in the 4000rpm-7000rpm band, so your gearing needs to keep it in that range at the speeds youll be using it, which is rather obviously best accomplished with a 3.90:1-4.56:1 rear gear and a manual transmission OR an automatic with a minimum 3700rpm stall converter, and the cam requires a 10.5:1-11:1 static compression ratio, a cam like thats going to use roller rockers and a rocker stud girdle

flat top pistons and 70cc heads, are going to get you into that range ,more easily than the 80cc unless you run a small dome piston, assuming the blocks been decked only slightly and your using average components to get in a decent quench range

here use these calculator,s assume your valve clearance notches total about 5cc-7cc and youve got a deck height of about .017, and a head gasket of about .027-.032 and youll degree in the cam

http://www.kb-silvolite.com/calc.php?action=comp

http://www.crower.com/misc/valve_timing_chart.html

obviously thats an rpm range where an intake like the weiand/holley 300-10 intake and a 850 holley

or better yet some decent single runner efi was designed for

http://www.compperformancegroupstores.c ... ry_Code=GM


http://www.carburetion.com/Weber/wildv8.asp

http://www.superchevy.com/hotnews/sucp_ ... index.html

http://www.compperformance.com/Technica ... PDF/31.pdf

http://www.imagineinjection.com/superchevy.html

viewtopic.php?f=55&t=2078

will this help
http://www.compperformancegroupstores.c ... ry_Code=GM
http://www.summitracing.com/parts/HLY-300-110/

 

[jteu2002]

oeps my mistake the new eliminator 220 afr heads are 65 ore 75

specs

sec gen transam weight ????
4.10 rear 275/60x15 tires
th400 manuel
4500 stall converter
block is zero decked

0.40 over so 4.165 pistons
5.7 rods flat top pistons with valve relief (5-7 cc )
0.039 headgasket
bowtie singleplane intake
DP 850
hooker supercomp headers
3"dual exhaust with X pipe and 2 dynomax bullit
use strip and a street (limited to 10-15 mls trip)

 

[grumpyvette]

ID suggest the 75cc heads will be most likely easier to work out the correct 10.5-11:1 compression ratio with.