I'm putting together a 350 to get started for now, I've got parts for 3 motors, 2 motors came out of trucks 1 305 the other 350. I also have a HO 305 out of a 91 RS Camaro. I'm saying all that so it can be understood why I'm asking my question. The exhaust manifolds that were on the original motor out of my car got swiped out from under me while the motor was taken apart, I plan on using the manifolds from the HO. Now the manifolds from that have alot of tubing connected to them with a hose connector on the top of them, I plan on having a classic air cleaner on top sitting on a stacker to fill the space inside the cowl hood. What are all the pipes on these manifolds for and how can I get these to work on the 350. Now eventually Id like to put headers on but the funds are not there for them right now.

 

Those are the A.I.R. tubes - they were connected to the smog pump system. If you're not using any of it, you can get a standard NPT plug at any hardware store, and put it in place of the check valve on top where all those tubes meet up. Or you can cut the tubes short and weld them so they are sealed at the manifolds.

 

thanks, I was hoping I could still use them so I didn't have to try and use the manifolds from the other motors. Now I can clean them up and prep them to be put on the 350, thanks again

 

Or just take them all the way off the manifold and replace with four plugs per side.

 

Unless that '91 RS has RPO B4C, then it doesn't have a 305 HO. The best it can have is a 170 HP LO3, and those exhaust manifolds are not as good as the ones used with the 350s in the Z28s.
It'll run, up to about 4500, but you're still gonna be under 200 HP, no matter how your 350 is built.

 

could you please tell me what RPO B4C stands for or HP LO3 as well? If so how can I find out? what they are? I've seen numbers and such on them. I'm a new builder so I'm gonna ask alot of questions, sorry.

 

B4C was the RPO for the police package. Extremely rare. Basically, an RS exterior with the best Z28 and 1LE underpinnings. LO3 is the RPO code for the 170 HP 305. HP doesn't mean High Performance, it means Horse Power. 305s cannot be High Performance engines without turbocharging, and GM never did that.