Engine Question On Heads - Ford Motorsport

Discussion in 'Classic Mustang Specific Tech' started by 65-Fstbk, Mar 7, 2013.

  1. The heads I have are older aluminum type but were apparently good in their day. Better than stock anyway. They are Ford Motorsports M-6049-J302.

    I am new to the engine build thing and have a couple of basic questions.

    Q1 - These heads have been decked pretty much to their limit I think. If you were to put a ruler on the deck surface and slide it across it would contact the large valve ring which is sticking up past deck surface just a little. The cam I am thinking of using is a Comp 35-440-8 (Magnum 281HR) with lift @ .512. Do you think there will be piston to valve clearance issues???

    Q2 - the heads have valve guide plates but I don't see any seals in their. Do all heads need valve guide seals when guide plates are used?

    Thanks for your help.
  2. sounds like someone has milled a lot off those heads i would bet the valves will easily hit flat top pistons. there is no push rod seal only valve stem seals
  3. You will have to measure, regardless of what heads you use. Are you looking at only a flat top piston? Most come with a cut out, for intake and exhaust valves..Depending on how far the heads have been milled, you MAY need to mill your intake to fit..
    Best bet will be to mock them up, and measure everything out..
  4. Thanks guys. I am re-using the stock 5.0 forged pistons b/c the block is really in good shape. Not even a ridge at the top of the cylinder sleeve and the cross hatching is still easily visible. The stock pistons have the valve reliefs in them which I'm hoping will be just enough to make it work. I s'pose I'll get the play-dough out, mount the head and hand crank it to see. I'm kind of worried that the hydraulic lifter may give if things get close in the cylinder which will not give me an accurate reading.

    horsesense - thanks for the info on the seals
    woodsnake - Thanks for the info on the intake. I will be checking that for sure.
  5. the hydrolic lifters will be flat so you will not get an accurate reading
  6. You can covert your hydraulic lifter to solid so you can get an accurate reading on P-V clearance. Just remove the clip and take the lifter apart, you can stack washers inside lifter to where you have just enough give to the pushrod cup to put the clip back in. I used a 1/8" pipe coupling with a 1/8" pipe plug to adjust height to barely get the clip back in, and whala, solid lifter.
  7. Thanks for the tip, I am going to try that. If P-V clearance is too close I always have the stock heads to fall back on. Could always use those until the future when budget allows for more upgrades. Thanks again!!!!
  8. Here's a pic of the deck on my heads. Does this look ok for a street motor? Piston to Valve clearance is what I'm concerned about. Cam I'm thinking of is a Comp 35-440-8 lift is .512. M-6049-J302 Heads.jpg
  9. they look like they have realy been shaved. best bet would be to set them up and chech the valve to piston clearance. they are at least going to raise the compression
    the valve doesnt look like it will be below the head gasket so it would be the lift that i would be worried about.
  10. PTV clearance should always be checked - you can buy a single hydro lifter and convert that to solid rather than converting one you plan to use. You can probably convert one to solid and convert it back to hydro and then use it, but I always worry about the little spring clip and whether everything will stay together at speed once I've had it apart and back together a couple times. I would tend to worry more about whether there's enough material left in the heads for a good strong seal to the deck than about PTV clearance. After checking PTV clearance you should probably mock up the intake to make sure the intake won't need to be milled to seal up and match with the ports on the heads. If the heads have been milled a lot you will want to make sure you check the pushrod length and use the correct pushrod length or your adjustable length pushrod when checking PTV clearance.

    If they were mine I would also take them to my local machine shop and have them checked for cracks, get them cc'ed, make sure the springs are set up and shimmed correctly so they will work properly with the cam, valve guides are good, valve seats in good condition, etc. It doesn't cost that much and you want everything to be right to make sure the motor will function the way you want. Without knowing the cc volume you don't know what the compression ratio will be and whether it's pump gas friendly, etc.

    Has the block been decked? How far in the hole are the pistons? Compressed thickness of the head gaskets you intend to use? These are other things you should know to calculate compression ratio. I recommend you also check dynamic compression.