I have owned a 90 Iroc for some time now. Checked out the VIN when I bought it and its an IROC. Not a RS with IROC components. However I keep reading on these boards that the z28's and the IROC's came with a 145 speedo. Mine has the 110 and came with the 305. The only reason I could think it came stock that way is because it's a convertable 5 speed.

Anyone know for certain?

 

Not all of them came with the 145 speedo. The 85's did not, and none of the carb. or TBI IROC's did either. Also, for 90-92, IROC's and Z28's that were convertible or had the 235/55R16 tires had the 110 speedo.

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89 Transam GTA, 350TPI, auto, 3.27 rear, dual cats, gray.
Magnaflow cat-back,
K&N open element,
Best E.T. 14.63@95mph

 

i haven a n 86 TPI Iroc with an 85 speedo.. so no

 

Also, they were introduced in late 86' on the TPI 305 only.

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89 Transam GTA, 350TPI, auto, 3.27 rear, dual cats, gray.
Magnaflow cat-back,
K&N open element,
Best E.T. 14.63@95mph

 

Hmm, all three of my thirdgens have had the 145 mph unit. That's a 85 IROC, a 86 IROC, and a 87 Z28. All 305 TPIs. Who knows if they were all original though...

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Ray87Z
-Vortec headed 350.
86 IROC w/ a cammed 305 TPI.
Formerly Ray86IROC.
www.inter-scape.com/Ray

[This message has been edited by Ray87Z (edited June 07, 2001).]

 

My 89 305 Tpi Iroc has the 110. Who knows if somebody swapped guages before they sold it...not that anyone I know would ever do a thing like that Actually my guage tends to read 3 mph slower than autoxray says i'm going to who knows?

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"Life is pain! Anyone who says differently is selling something."

 

I have an '88 Iroc with a 115 mph speedo

 

My 84 Z has one! I put it there though. It was out of I think an 86. I'd have to look at the car that I got it from to check thi VIN to see what engine it had.

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Working on:
'84 Z28 LG4 305 with 200,000 original miles!
Added dual elec fans.
145 MPH IROC Speedo
Building 430 HP 350 (ZZ430)
using primarily GMPP parts.
Short block sitting on a stand. (Man, those Fast-Burn heads look good, (just sitting there doing nothing!LOL))

Starting to look like the Kicker poster child!

ASE Certified Master Tech