617 turbo egr exhaust manifold

[macdoe]

Hello, We are cleaning some of the parts for reassembly after a head rebuild and I have noticed a difference in the xhaust manifold runner on the #2 cylinder exhaust port.The car we are working on is a 1985 300td. I had to take apart a spare motors cyl. head to get some valves when they rebuilt the 85 head.

The spare motor came out of a 1982 300sd. I was looking at this same #2 port on the 82 exhaust manifold and it looks to be more freeflowing when comparing it to the 85 ex. manifold. The manifolds look the same except for the #2 ex port. I had noticed a different part number on each as well.

Anyone have an idea why they would change the ports on these exhaust manifolds? The head off the 85 got rebuilt because of a broken exhaust guide on the # 2 cylinder as well as I caught a head gasket leak in it's very early stages.

I am wondering which manifold to use? Common sense tells me the one that is less restrictive but thought maybe there was a reason for this change? Did they do it to balance out flow or something...which one is better?

[Simpler=Better]

I don't know for sure,, but you can easily get irregularities with cast manifolds. I'd just hit each port with a grinder and match them to the manifold gasket.

[macdoe]

Thanks, Yes someone did mention that they had a grape sized irregularity in their manifold that they ground down as you mention, but I think our 85 manifold has had this done on purpose from the factory, it does'nt look like a casting irregularity to me, but maaybe it is...dunno. I used the 82 sd manifold anyways, it was cleaner and in very good shape.The #2 port turns straight down on the 82 sd manifold whereas on the 85 td manifold #2 goes in for about three quarters of an inch and then turns down. I'll try to get a picture of it if the camera ever works again.

We did not port mach any gaskets, just polished the cyl. head runners....and the shape of those was not changed except for some minor casting irregularities as you mentioned.

[oldsinner111]

maybe one is Federal,and other Californian ?

[Simpler=Better]

It's definitely a casting irregularity- a core shift. They made the walls thicker on mine to allow for tons of space when it came to drilling the holes for the studs. Mass produced cast iron parts from the 80's.....not what I would call perfect from the factory