I wish this post were to inform you all of which speedometers are correct in which year with which motor, but it's not. This is what information I need from a reliable source.

I was under the impression that my '89 IROC-Z with LB9 and 5-speed manual was supposed to have a 140mph speedo; in reality it has a 115mph speedo and I'm concerned with whether or not this is correct. It's missing the RPO code list and so I am concerned that something happened and has been sort of covered up.

Any info at all as to this topic of which is the correct speedo would be very helpful.

Later,
Kevin

 

Look in our Tech Data on the main page.

 

Thanks for the advice. I found the info I stated above at a different website and for the life of me I can't remember which one although I think it was an IROC-oriented site.

I've been through all of our tech data at this site - can't find anything relating to speedometers and engine combinations. Any other direction for me?

 

There's gauge information in the Tech Data. Do a search on this board also.

 

I hate to resurect this again - I looked all over the Tech Data section and haven't found anything. I also searched and found mostly people wanting to know how to install a higher speed speedo.

If there is a place in the tech data I should be looking, please go ahead and say where it is.

Otherwise, please someone in-the-know chime in here - I'm just not finding that clear-cut answer. Again, it's an '89 IROC, LB9 with T-5 manual and it has a 110/115 mph (not 85, not 140) speedo - is this correct or not??? I thought all TPI, regardless of 5.0L or 5.7L were to have the 140, but that is where I am stuck. The car has a missing RPO list so I'm VERY interested in this speedometer thing to help prove that it is original in every way.

Thanks a bunch if you can give any useful help at all guys,
Kevin

 

The 115 speedometer is correct for TPI 305 without G92 for 1989. Since you are missing your RPO codes, one way of verifying G92 would be to check and see if you have an engine oil cooler, if you don't, then no G92, and the 115 speedo is correct.

 

Labrat - thanks a ton. I do believe there is NO oil cooler - it would have lines coming off the filter mounting housing if there were - correct? When I changed oil on it the first time I did not see any oil lines coming off at that point. Didn't G92 also have four-wheel disc brakes too, or was that still an option within G92? Mine has aluminum rear drums. This is really helping to calm my anxiety a bit about this car being screwed up in some way - I think it's all good. I believe it was broken in-to at some point because the drivers side door window is not original - perhaps somehow the center console glove box lid got damaged and the previous owner had it replaced for that reason - thus the missing RPO list......

Thanks again -
And if you can, confirm that what I said about the cooler and brakes is correct just for my own knowledge.

K

 

The oil cooler has lines running from the cooler itself (above the oil filter) to the radiator. It is not easy to miss, also probably not easy to remove.

Yes it would have four wheel discs standard.

Willie posted a response a while back on this. the 145 mph speedo is tied into the G92 option for 305's from 89 on. Not sure about 88.

87 is the only year where all TPI motors got the 145 speedo that I know of.