Re: 1974 - 232

[adh@xxxxxxxxxxxxxxxxx (Sandwich Maker)]

" From: farna@xxxxxxx
" 
" On May 12, 2005 andrew hay wrote:
" 
" > but for adaptation to a '64-'70 ['low deck'] motor there's the pushrod
" > length issue.  a '72-4 shaft head would be a positive swap though
" > probably not worth much effort; the '72-up 232/258 ports are smaller
" > than '64-'71 but flow better, primarily from raised floors iirc.
" > chamber size was 66cc from '68 to '76 but you'd lose compression over
" > the 56cc head on a '64-'7 six.  those were closed chambers too,
" > working well with flattop pistons.
" 
" The 232 and 258 used dished pistons, the 199 flat tops. I was going to
" suggest using 199 pistons if swapping on the head with bigger chambers,
" but if the engine is being rebuilt just buy the same year pistons! Rods
" are the same until the deck height change, then there is a change in
" length. I don't have notes as to what the lengths are though. 

actually, i think only '68-'70 199s used flattops; compression didn't
change when they went from the 56cc to 66cc chambers, and i've seen
reference to 'replace in sets' on early engines - 232s too.  there's
also a pic in the '66 tsm of a slug with a shallow crescent-shaped dish
i've never seen anywhere else.

at the deck height change ['71], the 199 disappeared and the 258
appeared.  the 232 got 199-length 6.125" rods and the 258 got
232-length 5.875" rods.  what a coincidence...

the 199 and 232 have the same deck clearance and must use different
slugs to get the same compression.  the 232 and 258 use the same slug,
so the 258's stroke is shortened slightly [~.050"] to increase deck
clearance and lower compression.

" > i'm wondering if the '99-up 4.0 iron split exhaust manifolds would fit
" > any of the 199/232/258 heads...  i know that 4.0 has the tiniest ports
" > of all.
" 
" I know several people who run 4.0L exhaust manifolds on late 70s/early
" 80s 258s. There is a port mis-match, but apparently the manifold flows
" so much better that there is no noticeable power loss. The slight gain
" may just be in the better exhaust system total, as all I know put in 2"
" or 2.25" exhaust and turbo muffler (one a free flow cat) along with it.
" I suspect no gain from the manifold alone because of the port mis-match,
" but no loss either. The two piece iron manifold should be the same at
" worst. 

hmmm...  it's a step forward just to know the bolts line up and it
covers the holes.
________________________________________________________________________
Andrew Hay                                  the genius nature
internet rambler                            is to see what all have seen

adh@xxxxxxxxxxxxxxxxx                       and think what none thought