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Today I brought home my unicorn, my last ThirdGen, the 1990 IROC-Z. Car runs and drives w/ no SES Light, also came complete bumper to bumper, w/ no frame damage and no undercarriage rot! Seller claimed a rebuilt 350 block was dropped in using all stock 305 tpi parts i'll clean it up and post a pic tomorrow. I'm stoked to say the least.
Here it is! The car came white and someone repainted it black, but it looks ok. Now onto this claimed "350" using 305 tpi heads & stock tpi setup. I've never seen blk/red valve covers which surprisingly looks half decent and I can't recall ever seeing a orange/red painted block, heads & oil pan so I'm running with the idea it's a 350. If I wanted to confirm the claim it's a 350 could I simpily check the PROM? Assuming one can't run a 350tpi on 305tpi tuning because I'd assume it'd run lean like in TBI and throw a Code 44. Also, while driving this car off the trailer and into the driveway I noticed a GREAT difference in throttle response in this car over it's TBI cousins, i'm loving the tpi.
And the interior isn't all that bad either... especially not with the power drivers seat option, and operational power rear hatch. Next post will be RPO codes to see if this IROC-Z came with any goodies!
So here's the RPO Code List, I can't tell if they're any goodies here but I can say the VIN plate and the VIN on this label match and it has the Z28 indicating it's a true 1990 IROC-Z and not a "clone". Is there an rpo code for a trailer hitch? This came with a trailer hitch installed and has a neat red bowtie hitch cover too.
To see if it’s a 350 check the block suffix and or casting number behind the drivers side cylinder head.
the prom might tell a story too.
To tight of a squeeze for a camera but it's definitely a 350. With the block painted a high viz color and there being no crud I could actually see the 5.7LG SGI stamp with a light, right where I've been told it's at 100 times before but couldn't find it on either 92 . This is a major WIN!
EDIT: The proof is in the pic
Last edited by 92RS-HeritageEd; 07-27-2019 at 06:56 PM.
Since they didn't make a t-top IROC-Z with a 350 I'd like to find out what this 350 is out of. It'd be nice to know if it's an L98, 200+ HP, etc but the only thing I've found besides the 5.7LG SGI I believe is DJ216 off to the left, and 638 cast behind the psp. Can't see anything on a pad on the front of the passenger side head, the ac components are all in the way. Maybe I should just be happy it's really a 350.
See what #s are on the cylinder heads maybe they will be ending in 083..Thats the heads that come on L98s
Didn't get to check the cylinder head casting today but from what the PO stated they used everything from the LB9 and just dropped in a 350 block when the 305 crapped out.
Today was somewhat productive, went to the BMV and grabbed a temp tag, cleaned all the for sale paint off the windows, Installed my sound system and extra ground cable from the 92 I'm selling, and blew all the debris and cobwebs from the engine bay. Since I had the panels off running car audio wires I pulled the ECM and found a NAPA Reman XTP650 marked w/ OEM reference # 1227730 and AXYD PROM.
Took it for a spin this morning, ran like a champ. The gauge cluster has a bad Tach board but there was another cluster in the trunk in a box-o-parts included w/ sale. Did all IORC-Z's come w/ clusters that were 145 mph or only the 5.7L?.
Didn't get to check the cylinder head casting today but from what the PO stated they used everything from the LB9 and just dropped in a 350 block when the 305 crapped out.
Doesn't the 305 heads have the 1.84 valves? The 084's. The 350 heads should have the 1.94 valves correct? I wonder if your injectors have been changed to 22# for the 350.
I'm pretty sure the 305 heads pretty much all run 184 valves .305 TPI heads are #081. 305 TBI heads are #187 . We had a carbed 350 in an old 34 Chevy coupe running 081 heads with a lil cam and it ran very strong.
Took it for a spin this morning, ran like a champ. The gauge cluster has a bad Tach board but there was another cluster in the trunk in a box-o-parts included w/ sale. Did all IORC-Z's come w/ clusters that were 145 mph or only the 5.7L?.
My 305 1990 IROC has the 145mph cluster......and 5,500rpm redline tach
Would you have the $8D ADX File or link? I downloaded one form gearhead-efi but once it was loaded into TunerPro it looked very different so I'm not sure I got the right one.
Would you have the $8D ADX File or link? I downloaded one form gearhead-efi but once it was loaded into TunerPro it looked very different so I'm not sure I got the right one.
I just have the one from gearhead, it worked when I had my 91 z28.
whats different about it dash/item list ?
Just went w/ what I had... this is NOTHING like datalogging on the 8746.
- What's the Target AFR / Why is it constantly red?
- Is the 7730 a faster ECM over the 8746?
- What does this log tell you about the cars operation, does everything seem normal?
Yes, The 730 ecm is faster than the 746 ecm. Im not sure why in the item list the target afr shows in red.
Any idea what injectors they installed on the engine ?
the engine looks like its running real lean, have you pulled a plug to verify how its running ?
Now that I've re-customized my gauges dashboard in TunerPro I'm leaning in the direction that you're right @Tuned Performance *If* stock LB9 Injectors are 19's, I didn't even know the BLM could go higher than 150.
It's almost like now that I'm learning more I was sold my unicorn... w/ a HALF-A$$ 350 swap leaving out the injectors and memcal. The PO obviously said fck it since it ran and drove w/ no SES light, but on a brighter side they did the HARD work putting in the 350 block. OTOH I'm also sure that a set of injectors and a memcal won't be all that cheap. Buying 2 ThirdGens in 3 months left me rather tapped out on the fun budget.
Blm max out on the lean side at 160
You should look at what southbay fuel injectors has to offer.
They have 22#hr Bosch 3s for relatively cheap but will require battery voltage offsets to be changed in the tune.
I believe there Delphi’s with are more expensive are a direct replacement injector.
As far as tuning goes I can update your memcal with a flash style eeprom and rent you a burner.
You might want to experiment with aujp 350 timing table vs axxb 305 timing table to see how each performs.
I can also uv erase your prom and make it a aujp or you can use a moates.net g1 adapter and eeprom.
The fueling might need so more datalogging and tuning after a starter tune is done. Who knows what camshaft it’s running.
I would pull a plug or two and look at its color. Do it engine warm to get the current reading. My guess it’s more white than tan.
If you do go with Bosch 3s mention tgo if you call in or tg11 online.
I checked into SBFI and they're highly rated. Their main site has the B3's for $165 while their eBay store has them w/ free shipping for $159. The tgo / tg11 promo would come in handy. At their lowest price they're about $100 more than the lowest priced competitor on eBay. Do they rebuild these B3's to the size and spec of the OEM injectors used in the L98? I thought I saw online that people used B3's in ford applications too?
They rebuild the Bosch 3 injectors. They also press on a adapter to make them the correct length.
others tell you to use two o-rings at the bottom. This can cause vacuum leaks.
There are knock off b3s on eBay for cheap. I had a member try a set recently and they kept running rich no matter how much fuel was pulled from the tune. The sellers answer was to hammer them and show a picture of the destruction for a full refund.
I would pay the extra money for real Bosch 3s.
I've been following your build, had a bunch of similar problems and also had Brian (Tuned) help me out when I went from a 305 to a 350. Not to hijack your thread but I have a set of both 19lb and 22lb Bosch 3 injectors from Southbay. They've probably got only a couple of hours on each set and they're just sitting here in baggies. If and when you're interested, let me know and I'm happy to move them on for whatever you think a fair offer is. I've gone down the twin turbo rabbit hole this past year so neither set will be of any use. Good luck with the build, l'll keep reading.
I've been following your build, had a bunch of similar problems and also had Brian (Tuned) help me out when I went from a 305 to a 350. Not to hijack your thread but I have a set of both 19lb and 22lb Bosch 3 injectors from Southbay. They've probably got only a couple of hours on each set and they're just sitting here in baggies. If and when you're interested, let me know and I'm happy to move them on for whatever you think a fair offer is. I've gone down the twin turbo rabbit hole this past year so neither set will be of any use. Good luck with the build, l'll keep reading.
The 24's will require more tuning to work. usually its not a matter of plugging in the injector constant but the volumetric efficiency would need work as well.
I think the 22's might be a better plug and play with there battery offsets changed.I think the above injectors would need double O-rings on the bottom to seal in a stock manifold.
Since they didn't make a t-top IROC-Z with a 350 I'd like to find out what this 350 is out of. It'd be nice to know if it's an L98, 200+ HP, etc but the only thing I've found besides the 5.7LG SGI I believe is DJ216 off to the left, and 638 cast behind the psp. Can't see anything on a pad on the front of the passenger side head, the ac components are all in the way. Maybe I should just be happy it's really a 350.
They did make an IROC-z with the 350 and T-tops. I happen to have a 1988 model configured as such. Maybe they didn't do it for 1990?
They did make an IROC-z with the 350 and T-tops. I happen to have a 1988 model configured as such. Maybe they didn't do it for 1990?
I'm no IROC-Zologist but I swear I read on here they didn't make one after a certain year based on structure / stability / safety, but i'm likely wrong though.
Installed the grid style tail lights, looks great. Installed rear hatch privacy shade... it pulls out and retracts as it should but where or how do I latch it?
Last edited by 92RS-HeritageEd; 08-04-2019 at 09:18 PM.
Installed the grid style tail lights, looks great. Installed rear hatch privacy shade... it pulls out and retracts as it should but where or how do I latch it?
It will hook to the plastic interior panel on the bottom side of your hatch lid. There will be 2 holes on the back side of it to hook in to. So, it will open up with the hatch when you open it
It will hook to the plastic interior panel on the bottom side of your hatch lid. There will be 2 holes on the back side of it to hook in to. So, it will open up with the hatch when you open it
Without access to that pad that's behind the AC/SP bracket I'm taking long shots at other ways to track down the specs on a 350 sbc while the P/O is searching for records but mentioned to his recollection it was a GM crate engine installed by a shop.
- From L to R, I see a BIG # 5 then 5.7LG SGI then I see D121, does D121 mean anything?
P/O Response: "What we do know is that the block was swapped out, as well as the crank and the main bearings and all that because the crank had seized. Everything else that was in the engine was reused which is lifters heads cam everything else to my understanding."
I guess it can be narrowed down to a 87-95 and the D121 should be the date code? April 12, 1991? 175hp, 215hp? Higher?
This became important once it sunk in that a older Mitsubishi eclipse smashed the gas on me on the highway and left me embarrassed and disappointed in the IROC-Z
Last edited by 92RS-HeritageEd; 08-05-2019 at 09:53 PM.
So this morning the P/O sent me an updated message, after speaking w/ the shop that stated the only thing they kept was from the intake up and the block is a long block kit? I guess I'll be pulling the valve cover on lunch break for those head casting #'s.
07-21-2019, 09:21 PM
i'll clean it up and post a pic tomorrow. I'm stoked to say the least. 
. This is a major WIN!
and disappointed in the IROC-Z 