[DeTomaso] C302B vs C302C EXHAUST PORT HEIGHT????? - 180 HEADERS

Daniel C Jones daniel.c.jones2 at gmail.com
Thu Oct 1 00:22:35 EDT 2009


> Do you know if there are deck port height dimension differences between 302B and 302C heads?

I presume you mean C302 and C302B heads and not C3 Yates (C3L or C3H).
In unported form, there may be a minor difference in where the port floor
is but that difference will be swamped by differences in porting and
milling done to the specific heads in question.  If by 302B you actually
mean B351, then there is a chance the flanges are different.  There were
two high port head exhaust bolt patterns.  The top row of bolts for the
early heads is about a bolt diameter lower than that of later heads.  The
very earliest heads have a flange that is straight across at the top bolt
hole so you can't simply weld up the bolt holes and drill them higher.
Though there were two bolt patterns, I've seen three variations:

 1. Late heads with raised upper bolt hole row.  Fel Pro p/n 1417 for A3
    cylinder heads (1.94" diameter round port size) is the proper gasket.

 2. Intermediate heads with flange that will accept raised upper bolt hole
    row.  If need be, the upper row of holes can be welded shut and re-drilled.

 3. Early heads with flange that has lower upper row of bolt holes.  Flange
    can not be drilled for raised upper row.

Pictures of the various exhaust patterns can be seen here:

http://www.bacomatic.org/gallery2/v/hidden/dan/dan-cars/album04/A3_early_exhaust.jpg.html
http://www.bacomatic.org/gallery2/v/hidden/dan/dan-cars/album04/A3_late_exhaust.jpg.html
http://www.bacomatic.org/gallery2/v/hidden/dan/dan-cars/album04/B351_exhaust.jpg.html
http://www.bacomatic.org/gallery2/v/hidden/dan/dan-cars/album04/C302B_late_exhaust.jpg.html

Safe thing to do is to send him a header gasket for your heads:

 Fel Pro p/n 1417: A3 cylinder heads (1.94" diameter round port size)
 Fel Pro p/n 1431: B351/C302 cylinder heads (1.81" diameter round port size)
 Fel Pro p/n 1433: Yates cylinder heads (1.86" x 1.68" port size)

Dan Jones



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