Warped aluminum heads?

Discussion in 'Fox 5.0 Mustang Tech' started by 5spd GT, Nov 23, 2005.

  1. Well my car overheated for quite sometime the other day/night and I have afr aluminum heads. What exactly needs to be done to the heads to check them? They will be removed here in about a month or so and I will perform a head gasket change.

    What would a machine shop do if they are warped? Mill them? I really can't afford anymore closeness on my p-v clearance and most likely won't have enough money for new pistons. So what needs to be done?

  2. How hot did your car get? If the heads were exposed to the heat for a very long time, they would have warped and you probably would have developed some leaks by now.

    Once you get the heads off, you can set them on a flat table to check for true-ness.
  3. srothfuss is right pretty much the only way. Depening on if/how much they are warped, machine shop will have to mill them to get them true again. If they are not that bad and require very little milling, maybe a thicker headgasket may help?:shrug:
  4. Are you replacing the headgasket because it's blown? Overheating does not necessarily mean HG issue..I thought you indicated earlier you had a Tstat stick. A decent machine shop will be able to run an indicator over the heads and see if they are out at all.
  5. They will check them for straightness and then give them a clean up mill. Probably won't take too much to clean up perfect. If they're 58cc now, i'd guess they'll be 56cc after depending how much they need if at all.

    I overheated mine once (belt snapped on the way home one night) and before I put my heads on my new motor I took them to the shop to have the springs installed and I had them give it a clean up mill. They went from 57.6cc to 55.6cc after.
  6. Old fashoined way flatness check....

    Use a machinst square or gauge block know to be flat within .0001. Shine a bright light on the side opposite where you are positioned. Look for light between the machinst square and the head surface. A 001. feeler gagure can also be used to determine if there is any gap between the head surface and the square.
  7. jrichker is dead on, thats how I check. Easy and cheap. Although if its not leaking there really is no reason to pull them off.

    no on the thicker head gasket, that gives detonation issues from the reduced effectiveness of the quench pad (unless your not running a lot of compression). alot of people think thicker head gaskets can drop CR (true), but it is only helpfull in open chamber heads in reducing detonation.
  8. The car past the 270* mark for a couple minutes. I don't know of any leaks as of now...but who knows. I'm not just worried about it. The car runs fine...

    I was just going to check them and pull them off. I don't mind swapping new headgaskets on. Gives me an excuse to clean them and get my valvetrain geometry better:shrug:

    I was hoping there was a way to "not mill" if possible...the thicker headgasket isn't a bad idea...I guess I'll see what happens when I pull them off...

    Thanks for the ideas
  9. Thicker head gaskets will ruin your quench and can make you more prone to detonation. Stick with something in the .039" range.
  10. What Grn92 said about quench is dead on -- you don't want to run a thicker head gasket.

    Let the machine shop check your heads for trueness; if they're gonna go through the block for you, on a rebuild, the heads should have a clean up cut anyway (.005" is plenty) to create a true surface with the proper finish for that shiny new head gasket you're gonna use.

    Curious -- how did it get to so high a temp? Why didn't you shut it down?
  11. I believe the headgasket Ed gave me was .039"...

    t-stat didn't open. I'm stupid (aka. long story):)

    This is on the stock guage as well though...everything seems fine.
  12. Well hopefully the stock gauge was off.
  13. If they were warped you would know it.How many miles on them?
  14. Probably about 17k on them.

    The stock guage has been consistent throughout the time I have owned the car...I will know more once I pull the heads later on...I know it got hot though...
  15. So how much does milling heads cost roughly? I'm sure it depends on how much:shrug: What is a good route on getting them milled. Should I measure p-v clearance and then get that number and then mill an amount until I feel safe and stay above the .080 intake and .100 exhaust number?
  16. Milling varies from shop to shop. I think it is around $40 a head around here.
  17. Yeah I got to looking into it and it is tempting but then it throws off p-v clearance (obviously) but also rocker geometry and intake sealing and port matches. Lots to look into just for a little gain:bang:
  18. If the heads overheated you NEED to have them checked and clean up milled. I paid $80 to have my TW heads milled .020". I forget what the cost for the clean up mill was because I had the springs installed and height set at the same time and I had them glass peened.

    It doesn't hurt to check but with your small valve and small cam, you should be well beyond fine. You aren't clean up milling to gain power, you're doing it to fix the most likely warp of the heads. Been there done that.
  19. My cam is similar in size as yours believe it or not...so we both run small cams together. And you have a whole 1/10th of an inch of intake valve on me. We are just small together again.

    My cam comes very close to hitting...

    I'm not talking about cleanup milling to gain power because why would a cleanup mill change those factors of geometry/mating surfaces/and p-v clearance that drastically. I'm talking about "milling".

    I "AM" going to have them checked. Why wouldn't I?
  20. You need to talk to a machine shop then, you sound lost. Do you even know what a clean up mill is or does? A clean up mill will surface the deck as much as it takes to be 100% true. Could be .040" could be .002" you won't know until its done/checked. If it gets clean up milled enough, it'll raise the compression enough to gain some ponys. Mine needed appx .015" to clean up taking me from 57.6cc to 55.6cc.

    I wasn't trying to say your stuff is small, I was saying mine was bigger and cleared fine. My old fti cam was VERY small for my liking but it was also designed to spin a tad higher than yours. I made sure not to make that small cam mistake on the new motor.