OK guys i searched hear and didn't find the info i was looking for so hopefully you guys can help.I have a 92 rs 305 tbi with a t5 with alot of miles on it and i have a 87 corvette L98 tpi with a 4+2 transmission with rebuilt motor and low miles that I'm parting out.
What parts do i need to save off the corvette for this swap and is there other parts that i will need i would like to have everything i need on hand when i do the swap.
Another thing i was wondering i live in the smog friendly state of Calif is there a difference in the smog on the 87 corvette L98 and a 92 z28 L98.
Anny help is appreacheated thanks. Craig

 

Hmmm, this could be a tough one.

There are MAJOR differences between '87 L98 and '92 L98. First and foremost MAF ('87) vs. SD ('92). '87 3rd gen L98 was single cat, '92 3rd gen L98 had dual cats.

But, your problems go a little deeper. The '87 Vette has aluminum heads and uses an external line from the exhaust manifold to the intake for EGR. '92 3rd gen L98 used the external exhaust crossover passage for that. 3rd gens never got aluminum heads.

You can't just set it up as a '92 Vette because the '92 Vette was LT1. If the motor change ref checks engine numbers, you're toast, anyway.

I'm not sure there is a good remedy for this short of a compassionate motor change inspector (not likely).

 

Thanks for the info I'm hoping someone hear in California has did the L98 swap on a RS and was successful with smog.

I did a swap on my 78 bronco to 97 460 efi i had to use everything of the 97 f250 and then go to the inspector for a sticker on my door jam now it gets a smog as a 97 and registered as a 78 what a gob that was.

You can swap hear as long as the smog equipment is the same year or newer i don't think the heads will mater or the engine number I'm wondering if i could use the smog equipment off the 305 on the L98 ?.

And I'm thinking maybe the ecm and a wiring harness off a 92 z28 with the L98 option ?.

I'm trying to avoid the referee that was a big pain in the you now what.

 

five7kid do you have info on the ECM for the 92 rs and the 92 z28 l98 is it the same ecm with different proms and the engine wiring harness also thanks. Craig

O wow is there a difference in the manifolds from maf to S/d i bet there is banging my head.

 

was a 1990 vette L-98 shortblock with 90 f-body 083 l-98 heads and TBI on top. Passed the visual & sniffer test fine. I used 1990 stock TBI electronics. However this was in my old 82 trans am so so I was allowed 6 degrees BTC and the L-98 liked that. I believe yours calls for 0 degrees and it will need 0-3 degrees to pass smog and I'm not sure how the L-98 will run with a max of 3 degrees timing.

 

The engine and heads matter.

I don't know how you can avoid the motor change process. With an "E" VIN, you would have different inspection items when you have an "8" system in there. Guaranteed to fail, I'd think.

 

mine was a VIN H and it passed visually as a 4 barrel and was smogged as that even though TBI was under the air cleaner.

 

You got lucky. That time.

There's a bit more difference between TBI and TPI, though.

 

Yeah till the motor got tired and started puffing blue smoke then it failed the new visual test. Then I gave up on the car and purchased a vette project to tinker with.

 

In 92 they made the 305 tbi 305 tpi and the 350 tpi so i think as long as i have the 92 tpi and smog on there it should pass i might have to go to the referee for a sticker and inspection.

What I'm concerned about is getting the 87 L98 to run correctly with the 92 ecm and smog is there any difference internally from a 87 to 92 L98 i now the heads are different is it enough to make a difference ?.


Hell ill spray paint the heads to match the block for the visual and the 92 z28 had the 700r4 i hope i don't get a check engine lite from that not being there ?.

 

You can spray paint the heads, but that won't hide the external EGR tube.

No problem getting the '87 engine to run with the '92 controls. But, the numbers on the block/head could be a problem.

It's up to you. Take you chances that the inspector doesn't know his head from a hole in the ground, or that you'll put a bunch of work into something you can't drive.

 

I agree with you i wont do this swap if I'm not 100% sure it will pass.

I'm pretty sure the numbers wont be a problem because say you cracked your block they don't expect you to find a block with the same numbers maybe the heads but i will double check on that.

I found some good info searching on this forum i need to read all of this a few times.

http://www.hotrodlane.cc/Streetstories/choosetpi1.htm
http://www.hotrodlane.cc/Streetstories/choosingtpi2.htm

 

do the inspectors really check casting numbers and all that in CA...if so WOW i thought i had it bad hear in VA

 

Yea i think CA is the worst its tree hugger central when i did my bronco swap i don't think the referee checked the engine numbers he did check the ecm numbers checked too see if i had the correct smog equipment and checked for CEL DTC on the ecm and then smoged it.

Then he tels me its not the right ecm i told him its the ecm from the truck that engine came out of he says his Internet alldata has a different number.

So i go to ford parts department and they say my ecm is one of three ecm for that year so they print the three different numbers on a dealer piece of paper and back to the referee i go it was a bunch of

 

The replacement has to be from the same year or later than the chassis. Period.

 

If you wanna talk to someone in CA who has alot of experience with the L98 and the smog issues, talk to either KevinZ or DynoDon. They are both very knowledgeable and both live in CA.

 

Thanks 3rdgenred i ma be going another way maybe Lt1 i will now in a couple days.

 

While a bit more involved, I don't think you'll regret going that route.