I bought a set of 350 TPI manifolds ( supposed to be 89's )off of eBay recently, soon after a saw a L69 car in the junkyard. Will the H.O. y-pipe bolt up to the TPI manifolds, I heard the outlets are the same size? What size cat did the H.O. cars come with?

The only difference between the TPI manifolds and the L69 manifolds is that the latter has a heat stove on the driver's side. The L69 y-pipe will bolt up, though you'll either have a spacer or an EFE valve between manifold and y-pipe on the passenger side. The stock cat is a four-bolt design, both in and out. If you can, get the y-pipe, cat (could be good), and intermediate pipe. I did the swap onto a slightly modified LG4. Damn nice mod on the cheap, $68.

JamesC

They junkyard that car is in does not allow cats to be sold. I don't know if they would just give it to me, probably not though. I don't want to sound like an idiot, but whats an EFE valve? I have never heard of it or a spacer being in the cars. I don't think my LO3 has either one, but it would be too small anyway. Should the junkyard car have one? I also have a 3" Hooker I-pipe so I don't need the junyard one.

If you have a carbed car, the car has an Early Fuel Evaporation valve between y-pipe and manifold (the butterfly valve closes on cold start and shifts exhaust under the intake to warm things up more quickly). The TPI has a spacer (in place of the EFE valve). I'll give you the spacer, should you need one, for postage.

JamesC

Thanks going to the yard tomorrow to take a look at the pipe.