Needed a new motor for my '78 F 250 and got a sweet deal on a '67 352. I got new donut gaskets from Advance Auto before installing the new exhaust. Went to install them today and the passenger side gasket fits perfectly into the manifold while the same gasket in the driver side is too big. Does it take two different size gaskets? What am I missing here?

 

Did some more searching, found the answer. Thanks for looking

 

Curious what you found I have been having trouble fitting donut on passenger side of my 390.

 

1965/67 F100/350 352 came with a heat riser valve, the left exhaust manifold is made especially for it. Same manifold/heat riser valve as 1973/74 F100 360.

There is a donut gasket (C5TZ-9450-A) between the heat riser valve/manifold. A donut gasket (C5TZ-9450-B) between the heat riser valve and the flange of the inlet pipe.

There are three different sizes of donut gaskets:

C5TZ-9450-A ~ 1965/67 F100/350 352: 2.32" I.D. / .058"/.063" thick before compression.

C5TZ-9450-B ~ 1965/67 F100/350 352 & 1968 F100/350 360/390: 2.28" I.D. x 2.75" O.D. x .59" thick.

C6TZ-9450-B ~ 1966/67 F100 352 with T/E (smog pump) & 1968/72 F100/350 360/390: 2.28" I.D. x 2.75" O.D. x .58" thick.

 

Thanks ND. Thats what I found, need the heat riser