CamaroZ_85

I plan on swapping my carb for tpi and my biggest conern is the cam...especially since i'm not sure how my current one would work w/ the tpi. it's a comp extreme 262, the specs are 218/224 .462/.469 w/ a 110 lsa. people say you shouldnt really go over 220 duration w/ the tpi. is this due to intake restrictions, or chip limits? i am considering getting into chip burning so this might not be such a problem, and i plan on porting eberything before i do the swap. also the 110 lsa is a concern, again, is this for computer reasons? and can this be compensated for by programming a chip? i was thinking that i shouldnt start w/ a cam thats gonna require extensive chip mods, since i will be new to chip burning and will probably have much aggravation w/ getting the car to run right. so the next thing i was wondering is if there will be a decent sized cam that i could throw in w/ a stock chip...something that i can build good torque with but not have computer troubles with off the bat.i have headers and cat back, 3.08 gears that a plan to upgrade, and i will be getting a hi-flow cat sometime too. lookin through the archives,i found that people are reccomending the ZZ4 for this type of application (i have the stock l98 heads) but i would probably have to keep the lift under .500 due to the springs (dont want to machine the heads) and to me the 208 intake duration seems a bit too small on the zz4, unless it doesnt make sense to go a bit bigger for some reason....also lookin at the comp xtreme 256, the specs are 212/218 .449/.456 w/ 112 lsa. what are your opinions on these???? thanks thats about it for now, please give me any help you can! thanks

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85 Z28- 350, Comp 262, Edelbrock Performer intake, Edelbrock 600 cfm carb and Edelbrock cat back, Summit headers and vette servo
-JVC, Eclipse, Pioneer, MTX, Phoenix Gold, Planet Audio

88IROCs

"LSA" refers to the Lobe Separation Angle, which is measured from the centerline of the intake lobe to the centerline of the exhaust lobe. The LSA plays a large part in determining the overlap period(when both the valves are open). You need some overlap, so that the departing exhaust column can draw the incoming air into the cylinder. But as you increase the overlap, some of the intake charge will be drawn into the exhaust, which will lead to an erratic idle. This causes problems with the ECM which is trying to hold the idle to a specific rpm(programmed into the PROM). You can compensate by adjusting the minimum idle rpm upwards(and adjusting all the related parameters) and by adjusting the TPS(you may need to open the throttle blades slightly at idle to achieve this higher rpm).
If you stick with a cam that has a LSA of from 112 - 114° you can avoid this problem.

branz28

With a custom eprom you may be able to stablize the idle but as said above your idle rpm may have to be raised so that it idles nice. Eprom burning can help with such cases as yours but it's alot easier on a almost stock vehicle.

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89 IROC-Z 350 TPI

-Flowmaster Catback
-Performance Resource Chip
-700R4 (Rebuilt) Too much done to actually list
-K&N Airfilters
-Ported Plenum
-2.77 Gears (not much to brag about but eh, its there)
-MSD 8.5 mm plug wires
-Gutted cat
-!AIR
-Gutted Air Boxes