Hi all, I have my 18V`s head almost ready to go to the machine shop
with the exception of what ever I can do to decrease air flow restrictions.
The head has previously been mildly ported, inside of the in./ex. chambers
have the casting bumps ground off. The chamber openings have not been
enlarged any. Judging by the way the gasket lines up there is plenty of
metal to remove from the head but the tube header is puzzling me. The header
is made of 1/4" flat stock with a welded buildup for the sealing surfaces,
the three 1 3/8" tubes go into one 2" tube,O.D. measurments. I can see where
I can bevel the steel plate for some improvement but the transition from
rectangle to round tube is abrupt. I have heard the stock cast manifold flows
very well, I do have one and can only see a small amount of metal to be
removed to match the gasket shape. I don't who made the tube header but was
told it was home made, I havent seen one advertized that looks the same. The
flat stock piece that connects to the head is one piece, keeping the header
holes spacing unchangable the three pipes go into one at the same spot and
the 2" pipe narrows a bit to slip fit into a 2" exhaust pipe. The header is
10 yrs old and has over 75,000 mi. but still seams solid. Maybe it`s time to
retire it anyway. Does anyone know the pipe diamater of the free flow exhaust
systems advertized in moss, or any other system for sale? I know I dont need
a full 2" system. Any advice and all opinions welcome! By the way the motor
has been bored .030 over and may or may not need rebore, has a warm cam, and
is fed with twin 1.5 hif S.U.s with K&N air filters and the pistons have 3
rings and shallow dish top. I dont know if the pistons make high compression
or low. The markings on the pistons are; RA2551030 and
TOP0015TG
Thanks in advance,
Marc Derenzy
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