I have a set of Doug Thorley headers that were on the stock TBI heads, and now they are on the Sportsman200s. Will these same headers work if I go to the cast Vortec heads?
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I saw a post where the stock manifolds will not work because they use the second outer most hole on the rear but the headers use the inner most hole which is the only hole on the Vortecs, so I should be ok I think, but want to make sure.
Thanks

 

i think they would work, ive never seen thorleys but if the mouting filange is big enough you could always drill a new hole.

 

Hello, The bolt pattern is the same, but the exhaust port is about 1/8 inch higher on the vortec heads, so they wont line up the way they are-- You can elongate the holes downward in the header flange 1/8 inch- Now you can slide the header up the 1/8 inch on the head and tighten it down and you are lined up perfect. If you lay a vortec gasket over your headers you will see how far off they are. Later, Dave

 

Thanks ya'll. I think I should be ok because the exhaust tubes on the Thorley's I have are a little bit bigger in diameter than the TBI exhaust ports were and currently the Sportsmans are "D" shaped ports and they work ok on them too.

 

Dave you sure about this?? I had several sets of vortecs I sold and not noticed this the intake ports sure but the exhaust? I have a set in the garage I'll have to see how they match a set of 1 3/4" hooker longtubes ......

 

He is absolutely correct.. I ran into the same problem. I was never able to find an exhaust flange with the bolt holes corrected for vortec heads.. Luckily my buddy is skilled with auto-cad and has a connection to a machine shop with a water-jet.

I know that I've taked a picture that demonstrates this but I can't find it anywhere.


-Matt