Join Date: Aug 2005
Location: Halton Hills, Ontario, Canada
The riser should just bolt onto a pair of studs sticking out of the manifold. If there are none present, you'll have to install them. The riser on my 289 was attached with one stud this way originally, before it rusted off.
And yes, I think there should be a phenolic spacer under the carb. You might run into drivability issues (like vapor lock, fuel boiling in the float chamber) without it. Basically, it does this by shielding the carb a bit from the heat of the engineso the fuel bowl stays cooler. The spacer also provides an outlet for the PCV valve gases to go back into the combustion process. The spacer also could be said to provide a little "ram" effect for the incoming charge also, similar to a miniature "high riser" manifold, by elevating the carb so the incoming charge develops more velocity.
My guess is that stock, your engine should have a 1 inch spacer, but I'm only guessing on this one. Someone should be able to correct or corroborate this height.
Hope that helps a bit.
[/SIGPIC]67 Fastback GT -- original colour (Frost Turquoise), orig engine. Pic is of me and the Mustang taken in May of '67, with original F70-14 Wide Ovals. Same car is now restored to "as new" but 3 speed tranny swapped out for 4 speed back in the mid '80's, with tach dash, original Equalock rear, Koni's, Opentracker UCA, LCA, roller perches and idler arm, roller bearing pedal cluster, Cibie headlights, 4100 carb (old 4300 put in storage probably forever)