Are LB9 and LO3 heads different? The reason I ask is because I have 2 friends. One has an 89 RS 5 speed that he converted to TPI from TBI, has an SLP Cam, cat-back, high flow cat and 3.73s. The other has an 88 IROC 305 TPI headers, cat-back, high flow cat, 3.70s and a ROD tranny. The thing is the RS is runs like 16.2 and the IROC runs 14.7, thats a 1.5 second difference, surely there has to some major difference, I was thinking different heads, does anyone know for sure what it could be??

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1987 Chevy Camaro IROC-Z
L98 TPI 350 (5.7L)
TH 700R-4 Transmission
Borg Warner 7.75" 9 Bolt Rear End

Current Mods: LT4 HOT Cam, Comp Cams 1.52:1 Roller Rocker Arms, Edelbrock TES 1 5/8" Headers, Hooker 3" Aerochamber Cat-Back System, Performance Resource Chip, Accel Ignition Coil, Cap, Rotor, 8.8mm Wires, K&N Filters, JET TPI Air Foil, All Free Mods, Falken ZIEX Z-Rated Tires.

Best ET (w/o LT4 cam): 14.32 @ 97.7mph
(corrected for elevation)

Soon to Come: 7.625" 10 Bolt with 3.42s and Accel TPI Intake Base

 

Dan,

Have them compare casting numbers and check the differences at www.mortec.com. or at http://www.racer-x.f2s.com/proc/engids.htm

There might be very little difference in chamber volume but a significant difference in port design and flow. Both engines are supposed to have similar compression ratios, so I would presume similar chamber sizes. This says very little about port design, however, and one of the heads may even have "swirlee" ports - you know - the ones that suck like water flowing down a drain...

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Later,
Vader
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"I'm'a do Things My Way - It's My way or the Highway."
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[This message has been edited by Vader (edited March 18, 2001).]

 

Thanks, Vader, does anyone have casting numbers for those heads?

------------------
1987 Chevy Camaro IROC-Z
L98 TPI 350 (5.7L)
TH 700R-4 Transmission
Borg Warner 7.75" 9 Bolt Rear End

Current Mods: LT4 HOT Cam, Comp Cams 1.52:1 Roller Rocker Arms, Edelbrock TES 1 5/8" Headers, Hooker 3" Aerochamber Cat-Back System, Performance Resource Chip, Accel Ignition Coil, Cap, Rotor, 8.8mm Wires, K&N Filters, JET TPI Air Foil, All Free Mods, Falken ZIEX Z-Rated Tires.

Best ET (w/o LT4 cam): 14.32 @ 97.7mph
(corrected for elevation)

Soon to Come: 7.625" 10 Bolt with 3.42s and Accel TPI Intake Base

 

Cylinder Head Casting Numbers

___casting # ___|__________________used for __________________
14014416 perim-bolt 80-86 LG4’s, 82-86 L69's, and 85-86 LB9 TPI’s
14022601 perim-bolt 80-86.267/305’s 1.84"/1.5" valves, 58cc chambers
14101081 center-bolt 87-92 LB9 TPI’s
14102187 center-bolt 87-91 LO3’s Swirl Port Head
10159551 center-bolt 87-95 305’s
10159553 center-bolt 87-95 305's (really good head that came on some TBI’s
10065205 87-95 305
10065207 87-95 305
center-bolt 86-up L98 vette heads (aluminum)
12509859 87-94 305’s
10243878 perim-bolt 96-97 L?? Vortec 305’s
12552520 perim-bolt 97-98 L?? Vortec 305’s Truck
10239906 perim-bolt 96-99 L31 Vortec 350’s