Hey all,
Very possibly dropping in an LT1 shortly. I know you have to use 3rd gen headers to get them to fit, but the LT1 exhaust manifolds dont use the same style emissions equipment connections that our orginal 3rd gen manifolds. Is there a way to use headers & all of the emissions equipment at the same time? I really dont want to have to "rig" anything with adaptors or small sections of hose.

Thanks,
Mark B

 

Does the clearance issue with 4th gen headers happen with the headers or the y-pipe?

Cause I was thinking of using shorty headers for a 4th gen and then fabing up a y-pipe to join them. That would be ideal if it will work. Any other ideas?

 

if you use 3rd gen headers that are emissions qualified, they'll have Air tubes and 1 oxygen sensor hole. At that point, you would need to add another o2 bung for the other header, and an egr port (if you really want to). So simply, 1 02 sensor is all that is 'really' needed.

keep the EGR valve on the manifold, and put a block off plate on the EGR inlet tube boss. GM even made the blockoff's for lt4 engines becuase the camshaft had enough reversion that egr was uneccesary. If anyone does a quick emissions inspection, they'll see that the valve is there, and not worry about the inlet tube. leave the egr soleniod and everything hooked up too. In jersey, I don't think the pop the hood anyway, just check with a mirror if a cat is in place.

everything else is straightforward. air tube to cat (if your car has it), evap canister, and thats pretty much it.

if you are using 96 and up OBDii Lt1, it might be a benefit to get an '8051 ecm and run OBDi, so you don't need the post cat o2's.

 

OLd thread, but....what about using all LT1 emissions equipment?

 

You can certainly do that. The only thing that might be somewhat different is the charcoal canister. It's been awhile, I don't know if the LT1 cars had a canister in the front or the back(tank). if it was at the tank, it's probably easiest to use the earlier car's canister.

 

You could use the thirdgen charcoal canister, just might have to run new vacuum lines to it. The LT1 canister is in the back but the LT1 Charcoal Canister Purge Solenoid is mounted on the intake manifold.

 

I never even thought about using the 3rd gen canister. I guess it could work. The 4th gen LT1 canister is attached to the fuel tank?

 

No, the LT1 canister is not at the tank, but mounted inside the driver side quarter panel behind a little plastic shield that looks like the front inner fenders.

 

I think they do a "sniff" test on anything prior to '96 in addition to physically checking for a cat. Can probably get away with blocking off the EGR if it will pass without it. Keyword is if.

 

why go thru all the trouble of a swap to keep the emissions stuff in place.

 

Because that's the only way to do a legal swap.

 

So it can be street legal in NJ. Unless there is a way around this.