I bought a set of the small block Thorton exhaust manifolds and am in the process of installing them on my 71 ragtop. They are advertised as bolt-on, but really not so much. The drivers side is designed to accept 2 1/4 Tubing, so my "stock" 2 inch pipe and exhaust flange are no good. The new stud/bolt spacing is 3 3/4" and of course the big hole in the middle needs to be a little over 2 1/4". Any recommendations out there? The passenger side is good, its already 2 1/4 pipe with 3 3/4" spacing, I wish I could find the part number for that flange but Im having no luck. TIA

 

Call Troy directly and explain your issues. I am certain that he will get you sorted directly as he takes a great deal of ownership in the products he sells. Please provide feedback on what you find out for other potential customers.

 

^^^THIS^^^

I've never heard bad things about the Thornton exhaust manifolds before. Maybe it was a fluke casting.

 

And on the ones I tested, the threads were metric, not US.