Anyone running a 489ci RB?

[MCODECUDA]

.030 over 426 with 4.25 stroke.

 

[MCODECUDA]

I guess the answer is that no one has tried out this combo.

 

[1 Wild R/T]

As a rule a bigger bore helps un-shroud the valves... The 4.25 isn't much smaller than the 4.32 but big valves need all the room they can get...

 

[MCODECUDA]

As a rule a bigger bore helps un-shroud the valves... The 4.25 isn't much smaller than the 4.32 but big valves need all the room they can get...

Good point.

 

[Challenger340]

If using the TF240's be sure and check closely the Valve to Cylinder Wall clrc on the small Bore Engines ?
Trick Flow advertise 4.310" "minimum" Bore for the TF240's... we've used them lower at 4.28" but it can get REAL dicey given the particular Blocks Cylinder Bank offset... so best Mock-up and check all 8 for clrc if planning the TF Heads ? And even then the Valve shrouding seems to negate the advantage of the 2.19" Valves ? We're seeing damn near the same power on the Dyno using Ported Eddy's.... the TF240's just are NOT shining for us until 4.375" Bores ?

 

[1 Wild R/T]

If using the TF240's be sure and check closely the Valve to Cylinder Wall clrc on the small Bore Engines ?
Trick Flow advertise 4.310" "minimum" Bore for the TF240's... we've used them lower at 4.28" but it can get REAL dicey given the particular Blocks Cylinder Bank offset... so best Mock-up and check all 8 for clrc if planning the TF Heads ? And even then the Valve shrouding seems to negate the advantage of the 2.19" Valves ? We're seeing damn near the same power on the Dyno using Ported Eddy's.... the TF240's just are NOT shining for us until 4.375" Bores ?

I wonder if notching the bores like was required when putting 340 heads on a 273 would help?

 

[andyf]

.030 over 426 with 4.25 stroke.

I have a 496 in my B body car. It is an original 426W block that has been bored 0.060 over with a 4.25 crank. It has TF 240 heads on it and made 610 hp with a mild hyd roller cam. Nice pump gas engine.

 

[wyrmrider]

yes you can bevel the tops of the block below the valves
stay away from thehead gasket and the top ring
it does not take much to make a difference
put the heads on the block, flip it over and scribe using a pick and dykem
no reason to go bigger than the head chamber
exhaust unless physical interference
remember some used plunge half moon cut instead of bevel on exhaust- does not matter

 

[MCODECUDA]

As a rule a bigger bore helps un-shroud the valves... The 4.25 isn't much smaller than the 4.32 but big valves need all the room they can get...

We will be running 440 Source aluminum heads with 1.81” exhaust valves so shrouding will not be an issue.