74 250 carb mani

[Scott Sappington]

One of my 250 engines (74HS) has a carb mount/manifold that requires no isolation/spacer for the Bing 54 measures 45mm. My other engine has the 42mm mani that requires the spacer.
So.. what were the two different applications for the 2 manifolds?
Any performance differences?
Any replacement material that can be used in place of the OEM Isolation space? I don't have the spacer.
*Anyone have the 45mm mani they might be willing to part with?
Weighing out my options. THANKS,
Scott "Rat" Sappington

[Scott Sappington]

Update: Got with Al B this week, no exact answer with the different manifolds, though he had a box full of misc and is sending 2 mani's to fit, one the same & one shorter along with a new boot. Installing a Gary Ellis ported engine (finally!) Can't wait to get the HS on the track. Keep ya posted on the performance level. Scotty "Rat"