Re: Iron Pukes & Chebbys

[adh@xxxxxxxxxxxxxxxxx (Sandwich Maker)]

" From: "Bruce Hevner" <scramblr@xxxxxxxxxxx>
" 
" >original chevy 153 - 3.875"b x 3.25"s, same as 230 six, 90hp with 1bbl.
" >chevy marine 181 - 4.00"b x 3.60"s, 140hp with 2bbl.
" >pontiac 'iron duke' - 4.00"b x 3.00"s.
" 
" >it was the poncho that had all the gm speed equipt.  it has similarities
" >with the chevy four but a lot of things are changed.
" >stock blocks are significantly lighter than chevy 153/181, things like
" >bearings and wristpins are smaller.
" 
" >they all - chevy six included - have gear driven cams.  that's why the amc
" >six hei swap needs an amc gear - cams spin opposite directions,
" >distributors don't.
" 
" >also, the 153 and 230 use 283 sbc pistons.  rods are similar too, but wider
" >on the big end just like amc 258 vs. 304/360 rods.
" 
" Kinda right and kinda wrong.
" I have owned AND worked on all three of those engines.
" The original ChevyII 4cyl (which is what I traded in to buy my new Javelin
" in 1968) was not a very good engine although you COULD use SBC pistons AND a
" SBC head (with heavy mods). They ALSO had a "Marine" head for this motor
" which had better ports than the street version. They were used a good bit in
" Midget racing back then.

stock slugs for the 153 and 230 were equivalent to low-comp 283 slugs.
they put high-comp 283 slugs in the fleet truck 230 lpg option - at
least, replacement parts cross.

" The "Chevy Marine" (they were known under several different "Marine Brands")
" and "Iron Duke" are the SAME motor with a few differences. They are ALL
" Pontiacs actually.

i don't know if that's true now, but the 181" marine four came out in
the late '60s - looong before the iron puke was a sty in its
designer's eye.  and that marine head which fits the 153...

and yes, it did sell under lotsa names - omc and mercruiser, for the
most famous.

" These engines underwent a LOT of changes over the years.
" I know of at LEAST five different piston changes and MANY cyl head & head
" gasket changes. SOME of the heads will interchange & some will not
" (different head bolt pattern). They are TOTALLY different from the earlier
" "Chevy" 4 cyl.

i do know this is true of the iron puke.  it would be unfortunate but
plausible if they replaced the chevy-based 181 with a poncho-based
one somewhere along the line.

" When I had my shop a local marina approached me with a problem. The
" "Mercruiser" 181's were galling piston skirts left and right. These were new
" boats with just a few hours on them. The factory had assembled them WITHOUT
" torque plate honing the blocks. The cylinder bores were SO far out of round
" []

this is an almost-40-year-old engine which never sold in vast numbers.
could be they got sloppy with worn out tooling, and the move to mexico
could have happened about the time of this problem...

since the '60s at least, chevy and ford were both exercises in how
sloppy an engine you can make without its actually blowing up during
warrantee, because precision costs money, and they had the volume to
make the experiment pay.  chrysler, amc, and even other gm divisions
[for a while] were much more picky about allowable tolerances.
________________________________________________________________________
Andrew Hay                                  the genius nature
internet rambler                            is to see what all have seen

adh@xxxxxxxxxxxxxxxxx                       and think what none thought