oh a little nerve-wracking because how many heads do you have i don't
have that many this is like my last spare head so hi i'm paul brodie we're in my shop
thanks for tuning in me up here with some engine stuff mitch behind working the cameras
today we're going to work on aramaki stuff and we've got a couple heads here and i want to show
you some differences between a stock head and a racing head i know most people don't know much
about aramakis aramakis were made in italy and from 1960 to 74 they were owned half owned by
the harley company it was an unlikely marriage holly needed small bikes because of the japanese
coming over here honda yamaha etc so they purchased half year imachi factory and then the
mackies were re-badged as holly sprints that's the basic story in a nutshell so these are 350s
350 cylinder heads and this is known as the knucklehead because it had the bumps and the
lumps all over it there was also a smoother head it was called the ashtray head i don't like those
as much this is the cooler head for sure this is my race head here this is off my race bike
this is a stock head and what's happened on this is it's been milled down so what
we're going to do today we're going to mill about 60 thou which is a 16th of an inch
off this head you can see here they've had some issues here see all those little marks they made
there's a gasket this is off the other other version the ashtray head there's a gasket that
goes there and it seals it well this is probably what it came off and someone has made a gasket
here because i can tell they made it because on the stock one it's got a rounded edge here and
see how this one has a sharp edge so they've they've had a problem with it moving around so
they've put all these punch marks here so there's a relationship between this surface and this
surface because when when the liner goes in here and it doesn't use a head gasket it's just metal
on aluminum this is probably cast iron you have to have the right space so that it grips this seal so
this is the fixture that i made up years ago and this gets held in the mill in the rotary table
and this goes up here like this this fits like that this is basically in the center of the
of the bore and we might have to move it around a little bit and these rest on on top of here
and then this screws into the spark plug hole and then i i tighten up the allen screw
because i can't hold it from the bottom this is the area here i can't hold anything in here
because this is getting milled and then we have to mill down the face as well so this is what
goes on making an aramaki race bike raising the compression years ago when i was racing
i hadn't mailed this and i milled it in between races and i remember the next time it went out to
the track the engine was definitely louder everybody noticed that my exhaust note was
louder and everybody also noticed that my bike was noticeably faster too so raising the compression
definitely helps when you want to go fast so first thing we're going to do is to measure
between here and here and i also i don't know how accurate this is all around
okay so then i got 396. we'll check on here
that's 396 as well 3.98 so let's call it 396.
let's just have a quick look at this head
396 okay so this one got milled i want to show you something else that's going on with
these two heads here's the valves these are the valves that came out of the of the stock head
and these are the valves that get used in the race head 7.5 millimeters
seven millimeters and this one is six millimeters so if i put this into the
can you see this look at that huge whereas over here
that's a pretty good fit a little bit loose another thing i want to show you on the valves
is that these these are the stock valves can you see how it looks like they've gone to some
weight saving lengths but what happens is when when you do that you might save some
weight but you lose compression hard to get a good compression ratio when when the valves are
hollowed out like that if you look at the race valves they're flat so you know the compression
is going to be higher what i want to do now is i want to weigh these i haven't weighed them i could
have weighed them but i thought i'd wait till now and we'll we'll all have a look at the same time
i want to know if these have a smaller stem are they the same weight or are they lighter or are
they heavier i want to know okay first we'll weigh the stock ones here's an exhaust valve
okay this is uh 51.1 i'm gonna i'm gonna write it right on the valve the intake it's got the hollow
60.1
oh okay so it's 57.8 so that's a little heavier than stock then on the intake
that's got the small six millimeter stem we're at 64.4
so we've gained about four grams so it's comparable but we get higher compression so
that's that is the trade-off okay we're mounting the fixture onto the top of the cylinder head
last time i used this was
i think over 18 years ago i did a calculation so this is sat upstairs for almost two decades
i think i did maybe three heads with it in total so it's not like it got used a whole lot
i would never throw it away some people are going to say well why don't you do this in in the lathe
and that's a valid question but this whole thing only gets held by these these three six millimeter
allen screws so it's not exactly held hugely well so when this thing is spinning around
and if the tool bit would catch and move there's too many variables so we're not going to do that
okay so the head is now held in a fixture like that
let's go to the mill i want to show you something over there too follow me okay see here how i can't
i can't really move it because it's in gear on my particular mill if i take a quarter inch rod
see here this is the shift lever between high and low if i put that in there like that now i've got
neutral i'm not in gear at all why i'm showing you this is because i i needed to zero the head
i need to know that it is perpendicular with the mill table so can you see here i'm at zero
and if i lift this up very carefully
come around to there okay that's
i can live with a thou so that's how you zero it you have to go back and forth and you're making
adjustments and then when you're happy with it you say okay we're good so that's what i wanted
to show you so now i'm going to set up the rotary table because if the head's at a small angle
and i've got an end mill going around there it's not going to be perfectly flat it might
look okay but this is you need to be accurate on engines you can't you can't mess around
what we have to do now is to dial up this surface here we need to put an indicator on here
and if it's not quite right i need to loosen these and move move things
a little bit because i can't move this in the fixture it doesn't work like that
that is zero
oh it looks like it's going for a ride
interesting how it looks like i started on the low spot there
okay so somewhere that's that's kind of opposite somewhere around there we're at 35.
okay so what has to happen is this has to be moved up to 17 about
okay that's my lead hammer that i was looking for my friend tom meller made that it's a
really handy it's a piece of copper tubing and you melt lead into it so it's it it doesn't
damage it needs to go to right about there the 17 and hopefully not shift either way this way
and i'm not supposed to hit against the dial i know that so i'm going to hold it
oh did that move
well
i think what we're going to do now is we're going to zero that snug these down a little bit
and see what happens okay we're at zero right here well we're at one there
there's zero and with zero right there this is looking promising
we're at -2 i mean we are talking width of a human hair here so i think maybe we're good
this is a half inch rod here i'm going to move this so it's at the zero and then i'm going to
lower this down use a piece of paper that's going to set my y because then i won't have to
move it until this hits the wall because i don't need that so here's my paper
oops there goes see that it's just grabbing i'm zeroing my y that's my zero there
okay i think we're basically ready to start milling a little nerve-wracking because how
many heads do you have i don't have that many this is like my last spare head so
i've got 1500 rpm
yeah hear that it's just it's just touching so i'm going to set this to zero
i'm going to take two cups of 30 thou that's that's what i want to do
actually maybe i'll do three cups of 20 i'll be on the safe side
see off the table this is a long way off the table so if you take a heavy cut
you can get vibration so we don't want vibration i'm making a mock where i where i start
see there's a tiny lip right there i think what i'm going to do is i'm going to pull
the head in a little bit so that the end mill is going to cut just a little bit more there
you can you can see that can't you
okay that's moved tooth out
so i noticed one thing we're getting we're getting pretty close to that
intake seat that's this is the intake we don't have a lot more to go so maybe
i don't want to hit the seat really so maybe we'll go 15 thou and we're still not taking any
metal off the outside see that little lip there so i'm gonna move it another couple
thou and we'll take off i'm gonna i'm gonna bring in the head a couple thou
and we're gonna go down fifteen thousand okay so here we go
so this is where i was ramping down i'm not ramping up
ramping the head up ramping the tool down
so i lowered the table there to end the cut and i guess it things move so
basically there's not much left there in between the valve seat i haven't hit the
valve seat because i didn't want to that because that's hard i'm i'm down as far as i can go
basically so i took off 55 fell so now we have to have to change the cutter and we have to mill
all this here down to the right height i just want to touch very lightly it's almost a auditory thing
there you go can you hear that
so
i have to bend down so when i'm bending down all
aluminum never tastes good it's got this weird taste to it so we're going down to 396.
so i'll take off another 20 thou and then we'll do one last check
i'm gonna say 4 12 4 14. i'll trust this more okay last cut
oh
so we're at 396.
hey thanks for hanging out in our shop here it's good to have you along mitch and i like
coffee you buy us coffee it fuels our channel take care hope you enjoyed this see you next time bye