questions about my 89 iroc please help me out - Third Generation F-Body Message Boards

89iroc-z559 · 06-27-2009, 05:44 PM

hey guys

i have a few questions about my iroc. i have a 89 iroc-z28 5.7 tpi auto. first of all i see people putting lb9 and l98 how do u know which motor you have? also i was wondering if theres any threads that show u how to build up my engine becuase i dont reallly know how and i want to learn. last question is see alot of the 383 stroker stuff im the forums can someone explain what that is? is it like a swap or is it just an upgrade?

This ad is not displayed to registered members.
Register your free account today and become a member on ThirdGen!

Johnknight1981 · 06-28-2009, 11:40 AM

the best and fastest way to find out which motor you have is by looking at the VIN number. count the VIN until you get to the 8th digit. If the 8th digit is an "8" then you have a 350, if its an "F" then you have a 305. Iroc-z's also had the option to get the 305 tbi so if the 8th digit is an "E" then you have a 305 TBI, which in turn is only a 170hp base 305.

As far as what a 383 storker is; a 383 motor has been changed over the years. use to be the only way to have a 383 was to have a 400 motor destroke it by using a 350 crack and do somthing to the oil jornals. Now there is a way to replace the crank on a 350 motor that strokes it, you'll have to bore the motor .030 over which means new pistions as well....might as well get new connecting rods. usually a rotating assumbly kit is acquired for everything to stroke a 350 to a 383....or, if you got the money for it...simply buy a 383 crate.

89iroc-z559 · 07-08-2009, 06:01 AM

thanx alot for the information
also i got the 8 in the vin # so its the 350 so does that mean its a l98?

Abubaca · 07-08-2009, 09:28 AM

L98 is the RPO code for the 350 TPI. VIN shows and "8"
LB9 is the RPO code for the 305 TPI. Vin shows and "F"

As stated, you could also have the tBi 305, which shows and "E" on the vin. Not sure what the RPO is though. Maybe L03? LG4? Not sure. But as we've determined, you've got the L98.

As for learning about motors, here's my advice: Go to a local bookstore and buy one of those half inch thick books on tuning and modding a chevy small block. I have a few, but the one by John Lingenfelter was the best as far as "tech" in my opinon. It explains rotating assemblies, heads, cams, intakes, valve trains, bearings, machining, etc. etc. Now it is NOT a rebuild manual, but it'll teach you all the ins and outs, and if you remember HALF of it, you'll be good to go.
THEN. Once you understand at least the basic parts of the motor, then you come here and read and ask questions. The book will explain how the cam works, and what it does, and where it goes. THIS SITE will help with which cam will best suit a specific motor.

Cam profiles, tuning techniques, and new gadgets and gizmos change by the day, but the basics in that book have been the same since the 50's!!!!

....ya know, I actually have two copies of that one book. I'll check and see if I still have it. If so, send me a few bucks for shipping and you can have it.

Johnknight1981 · 07-12-2009, 05:29 PM

Yeap if the 8th digit is in fact an "8" then yes its a 350 TPI and the RPO code is a L98.
all L98 cars had Automatic transmissions. If you look in the center console you'll have a sticker on the inside of the console with all the RPO codes. All major RPO codes to look for are N10 (dual cats extra 10hp from GM) J65 (four wheel disk brakes) G92 (performance rear axle)