cylinder head work...

[unclejemima]

should i do anywork to my cylinder head, or can i just leave it stock after i put a super 60 with a .63 ar.
I am getting the head rebuilt, and want to know if i should use different springs/valves, ext.

The car is a 91 daytona shelby 2.5 TI

Thanks again,
-mark

well... i always do my own head-jobs(hi, hi, hi)
seriously, i like to do the job myself, cos then i know it gets done right. you can always enlarge the ports a little, and do a grind-job on the valveseat (mira-grind in swedish).
that means that you make the inner diameter of the valveseat about 0.3 millimeters smaller than the valve itself. standard issue valveseats are about 2 mm smaller.
this makes the ports larger and more air/fuel mixture can be delivered.

Also, you can blueprint the head to reduce weight on all moving parts and increase oilflow to the oilpan...

you can change valves to one size larger and the be able to open up the valveseats some more....

you can do many things, the head is, in fact, the most important part on the engine for performance...

how far you want to go is up to you!!

good luck and greetings from sweden!

[cj011]

can you share some more details regarding blueprinting the head to reduce weight, what areas are do you modify to loose weight or areas that you found where the most work can be done. also, what do you use to grind down the valve seat in order to attain .3 mm. i am on the same boat myself regarding head work. i would rather take my time and do everything right rather then waiting around for a shop to finish the job. plus your only have labor to pay, any food, and a good excuse for the wife/girlfriend to be working on a car part that long.

well i don´t know the english word, but i use a rotating "sandpapertool" for alot of work on the head.
i always use very fine paper so that my stupid mistakes does´nt destroy the head.

if you polish all the moving parts, they will work more easy and faster than stock. the surface of the inside of the head is often rough; polishing makes the oil less adhesive and will flow faster to the oilpan.

ill try to get som pictures and some drawings up later.

see ya!

[cj011]

cool, thanks alot for the info. i would have to definately agree with the use of sand tools when doing the work. cutting wheels or stones do not leave alot of room to make a mistake. personally broke through a manifold for a set of 48 ida webers, that i spent about two weeks on, had to spend another just on the repair. i got to close and simply wasn't paying attention, and the cutting wheel caught and slid, to a part that i knew was really thin. on the diameter of the valve seat, does it have to be a perfect circle, is there room to allow slight variations. is there any specific angles that you are after. also, how can you tell if the seat is finished or what is the proper shape that you are looking for ? personally myself, i haven't worked on valve seats, but have done everything else on the head porting job. my approach, which i am not saying is correct (but it avoids to big of port problem) is to start on the inside and work my way out. basically starting on the combustion chamber and working my way out the head. that way i can tell if the port size should be enlarged.

pics would definately be great

sorry to ask a ton of questions, but is rare to find someone who is willing to share even a tiny amount of info when it comes to head porting on a newer design cylinder head.

hello. here is a image that i made myself:
is this old news, or is this new fresh stuff?

...another one:

if you are really serious, there will be no room for anything else but a totally perfect circle! if you fail to do so, the top of the valve
will come tumbling thru the exhaust!! not good...
if you are not that serious, and don´t plan to do an extensive job, then you certainly can use sandtools to "make the hole bigger", cos then you dont remove the 45 degree angle on the seat.

i forgot to mention that grinding the ports is NOT the same process on both in- and outlet. i only do the inlet. once i tried to do the outlet, but it didn´t work that good.

and furthermore: LESS IS MORE! be gentle and don´t overdo it..

and also: don´t use grindingpaste! if the valves and the valveseats are polished and grinded correctly, they will have a 100% tight seal. grindingpaste will then destroy the perfect fit!

more to come.....

here is a pic of how to grind valveseats from UK magazine "Max Power"

[cj011]

great pics. on the picture that had grind away here and do not grind away here, why is the area chosen to not grind away. i do realize that if you create to sharp of a turn for the air to go around, that is bad, is better to go after a more direct route to the valve or a more contured approach where the air travels more smoothly?

[ToiboTonaZee]

The reason you dont want to touch the floor of the port is because you want the incoming A/F to hit the back of the valve, (kind of like a little plunger) as square as possible. If it comes at it from an angle it will cause turbulence. (bad)

[cj011]

so that is why it is okay for the air on the floor to go around the corner and then directly to the back of the valve. what about overall shape of the port, i have read that d is recommended, what is your thoughts? also, what type of mods can increase swirl in the chamber to draw in more air? i have a feeling that this thread may becomre a classic.

hello, boys!

i forgot to also mention that it´s very important to shape the ports equal to eachother then you grind them, or the cylinders will become strained differently wich will result in different wear on the engines different parts.

the reason you don´t want turbulence anywhere from the airfilter to the cylinders is (i have heard) that the theoretical volume of the intake becomes smaller.
inside the cylinder you should do all you can to create some kind of swirl to increase the velocity of the fuel/air mixture on its way down the port. the swirl also makes the mixture mix even better.
a swirl in the cyl´s is a main issue for high rpm motors.
i once made a toyota 1.6 16 valve that rev´d about 11.000 rpm.
(it didn´t last long, thou. i wonder why?)

I don´t know how important the swirl is on turbo engines, cos then the turbo pushes the A/F and obliviates the sucktion that the swirl creates.

A "Cross-Flow" cylinderhead is ideal for swirl in the cylinders.
cross-flow means that the two valves for intake shoots the mixture towards the center of the cyl. this makes the two streams of mixture "crash" into eachother.

volvo once made a head that was called "swan-neck" because of it´s extremely long ports that were made straight into the head, made a tight turn, and went down to the valves from almost directly above. this head worked very well...
long ports is also good for the engines temp. the intaking mixture cools the head down a little.

have you tried any of my tips?

.best regards from Sweden!

(ps. maybe you want to know how you, from using common household items, can make a tool to test the flow in your ports?)

[ToiboTonaZee]

Is this what i should be going for for the intake port? Il probably never get that far in but it looks very efficient...

[crazymadbastard]

I was told that on our engines the gains are mostly on the exhaust side. Also 90% of the gains are in the "bowl area".