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This is my combo 460 bbc scatt rotating assembly forged pistons forged rods cast crank 2 piece seal

Bore: (diameter)
4.280
Stroke:
4.0
Cylinder Head Volume:
119
Effective Dome Volume:
Use (-) for Dome and (+) for Dish.
-30.60
Deck Clearance:
0.0
Compressed Gasket Thickness:
0.041
Number of Cylinders: 8
Compression Ratio : 10.62 : 1
Total Displacement (in.3) : 460.39
Total Displacement cc's : 7547.38

Procomp aluminum Heads
Intake Valve: 2.250"
Exhaust Valve: 1.880"
Max Lift: .565"
Coil Bind: .740"
Intake Install: 130 lbs @ 1.8
Exhaust Install: 130 lbs @ 1.8
Closed Sear Pressure: 110 lbs
Open Seat Pressure: 300 lbs

Cam Hyd Roller
Cam Style:Hydraulic roller tappet
Basic Operating RPM Range:2,800-6,100
Intake Duration at 050 inch Lift:242
Exhaust Duration at 050 inch Lift:248
Duration at 050 inch Lift:242 int./248 exh.
Advertised Intake Duration:294
Advertised Exhaust Duration:300
Advertised Duration:294 int./300 exh.
Intake Valve Lift with Factory Rocker Arm Ratio:0.540 in.
Exhaust Valve Lift with Factory Rocker Arm Ratio:0.560 in.
Valve Lift with Factory Rocker Arm Ratio:0.540 int./0.560 exh.
Lobe Separation (degrees):110
Computer-Controlled Compatible:No
Grind Number:CB XR294HR-10

msd ditribuor with fast 6000-6400 with no crank retard

torque convert stall 3,000 rpm

trans is a 700r4

rear 12 bolt 3.42 posi

sorry for the long text but I just wanted to give you as much info as I can

here are the problems

the engine only makes 8 pounds of vacuum

Horrible idle if centrifugal advance is used, right now the timing is locked at 36
the car idle much better but it took out my first sfi flywheel with stater kick back,
I did rotor phase but had little improvement, anyways when I drive the car I can tell the engine is not happy at all, it would overheat, and just not run right, everything on this car is new. It's got a tripple pass radiator with dual electric fans 3000cfm

gotta a quick fuel 850 double pumper 70 jet up front 86 rear with a 3.5 power valve

finally I called comp cams and the want to change the cam for a custom 230/236 on a 114 lobe but they saying that the 10.60 compression ratio is too high for 93 octane

I'm completely at a lost ,I have try everything, right now I'm willing to do the cam swap but hesitating on the piston swap.

If I do the piston swap I much rather go for something to work on 87 pump gas cause now it looks like this car is going to be my daily driver for a while so I need to be reliable street friendly 67 camaro

cranking compression is 195 pounds

please know this is not my first engine build I'm an auto technician for a leaving and yes at first I wanted a really healthy weekend cruiser but now I need this engine to be very street friendly

thanks in advance
 

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put more timing in it and go from there with carb adjustments
 

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This is my combo 460 bbc scatt rotating assembly forged pistons forged rods cast crank 2 piece seal

Bore: (diameter)
4.280
Stroke:
4.0
Cylinder Head Volume:
119
Effective Dome Volume:
Use (-) for Dome and (+) for Dish.
-30.60
Deck Clearance:
0.0
Compressed Gasket Thickness:
0.041
Number of Cylinders: 8
Compression Ratio : 10.62 : 1
Total Displacement (in.3) : 460.39
Total Displacement cc's : 7547.38

Procomp aluminum Heads
Intake Valve: 2.250"
Exhaust Valve: 1.880"
Max Lift: .565"
Coil Bind: .740"
Intake Install: 130 lbs @ 1.8
Exhaust Install: 130 lbs @ 1.8
Closed Sear Pressure: 110 lbs
Open Seat Pressure: 300 lbs

Cam Hyd Roller
Cam Style:Hydraulic roller tappet
Basic Operating RPM Range:2,800-6,100
Intake Duration at 050 inch Lift:242
Exhaust Duration at 050 inch Lift:248
Duration at 050 inch Lift:242 int./248 exh.
Advertised Intake Duration:294
Advertised Exhaust Duration:300
Advertised Duration:294 int./300 exh.
Intake Valve Lift with Factory Rocker Arm Ratio:0.540 in.
Exhaust Valve Lift with Factory Rocker Arm Ratio:0.560 in.
Valve Lift with Factory Rocker Arm Ratio:0.540 int./0.560 exh.
Lobe Separation (degrees):110
Computer-Controlled Compatible:No
Grind Number:CB XR294HR-10

msd ditribuor with fast 6000-6400 with no crank retard

torque convert stall 3,000 rpm

trans is a 700r4

rear 12 bolt 3.42 posi

sorry for the long text but I just wanted to give you as much info as I can

here are the problems

the engine only makes 8 pounds of vacuum

Horrible idle if centrifugal advance is used, right now the timing is locked at 36
the car idle much better but it took out my first sfi flywheel with stater kick back,
I did rotor phase but had little improvement, anyways when I drive the car I can tell the engine is not happy at all, it would overheat, and just not run right, everything on this car is new. It's got a tripple pass radiator with dual electric fans 3000cfm

gotta a quick fuel 850 double pumper 70 jet up front 86 rear with a 3.5 power valve

finally I called comp cams and the want to change the cam for a custom 230/236 on a 114 lobe but they saying that the 10.60 compression ratio is too high for 93 octane

I'm completely at a lost ,I have try everything, right now I'm willing to do the cam swap but hesitating on the piston swap.

If I do the piston swap I much rather go for something to work on 87 pump gas cause now it looks like this car is going to be my daily driver for a while so I need to be reliable street friendly 67 camaro

cranking compression is 195 pounds

please know this is not my first engine build I'm an auto technician for a leaving and yes at first I wanted a really healthy weekend cruiser but now I need this engine to be very street friendly

thanks in advance
We recently dynoed a very similar build to yours, same exact Pro-Comp heads, same C.R., pretty much the same build? The one exception being we used the very cam you are looking to install, the 230*/236* x .576"/.550" x 112* (1.8 intake rockers). Comp part #01-451-8 (Marine grind #XM284-HR)

Unit made over 600 HP (630 to be exact), tested on the dyno with 93 and still running fine.

One other issue you have that I can see with that combo, assuming your numbers are "fact". is that you have the wrong springs in the program, you should be closer to 160# closed and 380#+ open?

Thanks, Gary in N.Y.

P.S. The cam number I placed above here highlighted in red, allows the use of the roller cam w/o the need for any cam buttons or end-play checking! In your case it would need a new roller timing set to go with the stepped-nose cam and the thrust-plate with the screws, but it will make the installation a lot simpler! This cam and cam setup is so popular with us we keep about 1/2 dozen in stock at all times.
 

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Not enough spring pressure, Who's lifters?

I just dyno'd a 565 pump gas deal with shitty heads and 11.5:1 compression with a BKR6E plug and 93 octane from shell, It wanted 38 degrees of timing and it made 720 hp....

carbs sounds rich, What heat range plug?
 

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Discussion Starter #5
Sorry guys I miss that but i did replace the sprngs in the heads with the ones the cam called for

Manufacturer's Part Number:930-16
Part Type:Valve Springs
Product Line:COMP Cams Valve Springs
Summit Racing Part Number:CCA-930-16

UPC:036584270515
Valve Spring Style:Standard
Number of Springs Per Valve:Dual
Outside Diameter of Outer Spring (in):1.550 in.
Coil Bind Height (in):1.160 in.
Damper Spring Included:Yes
Spring Rate (lbs/in):354 lbs./in.
Inside Diameter of Outer Spring (in):1.125 in.
Inside Diameter of Inner Spring (in):0.795 in.
 

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That cam is not big by any means, it should pull 12+" of vacuum under the carb...
Maybe you have a vacuum leak....give it more timing.
 

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Again who's lifter and what is the actual installed seat pressure and open pressure?
BBC have heavy valves
That 565 I did had 165 lbs seat and 450 open.
CAM was 256/264 on a 112 lsa with a 108 int c/l
 

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Carb primary jetting looks small. Have you tried jetting it up? Maybe lean promoting higher temperature. 76 with 6.5 power valve. Power valve does not effect idle circuit. Will bring in extra fuel accelerating cruise a little sooner. 3.5 power valves are not the hot set up on many applications.

Do you have a separate switch for ignition? You can get the engine spinning and then turn on the ignition to minimize engine kick back. Also the amount of fuel you introduce with accelerator pump before cranking can defect this at cold start.
 

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Discussion Starter #11
lifters are comp cams 854-16

wish I had to exchange twice do to excessive tcking noise

tie down 3/4 turn seems to be the quietest spot
 

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Discussion Starter #13
this is the battery
Brand:Optima Batteries
Manufacturer's Part Number:9002-002
Part Type:Batteries
Product Line:Optima RedTop Starting 12-Volt Batteries
Summit Racing Part Number:ULT-9002-002

UPC:811405000027
Battery Usage:Starting
BCI Group Number:34
Volts:12 V
Battery Terminals:Top
Battery Type:AGM
Cold Cranking Amps (0 degrees F):800 amps
Cranking Amps (32 degrees F):1,000 amps
Reserve Capacity:100 minutes

this is the starter

Brand:powermaster
Manufacturer's Part Number:9526
Part Type:Starters
Product Line:powermaster XS Torque Starters
Summit Racing Part Number:pWM-9526

UPC:692209006145
Starter Style:Mini Denso
Adjustable Mounting Block:No
Starter Rotation:Standard
Starter Finish:Natural
Maximum Recommended Compression Ratio:18.0:1
Gear Reduction Ratio:4.40:1
Mounting Block Material:Billet aluminum

I do have a push button to crank over the engine
 

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70 primary jet is pretty small on an 850,and the 3.5 pv seems light...Check intake for vacuum leak....have you tried 34* timing???
 

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Also recheck plugs wires cap and rotor as well as firing order, if you have access to a heat gun check individual header tube Temps
 

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3.5" powervalve isn't doing you much of a favor with 8" of vacuum, could easily be going lean due to the PV not opening much/too late. 70's definitely should be on the small side for primary mains, any vacuum advance available to help it cruising?


Was the cam degree'd in or just "on the dots"?
 

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Discussion Starter #19
when i hook up the vacuum advance the engine really start going crazy cause the vacuum pulse is not steady , it fluctuates up and down like a 1/16 inch from the 8 pound mark
 
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